remove unused files

.github/actions/download-kernel/fast_parallel_download.py

@@ -1,142 +0,0 @@
-#!/usr/bin/env python3
-"""
-Fast Parallel Archive Download
-
-This script implements the logic previously embedded inline in the action YAML.
-It expects to be executed with the working directory set to the kernel workspace
-where `manifest.xml` resides.
-"""
-import xml.etree.ElementTree as ET
-import subprocess
-import os
-import shutil
-from concurrent.futures import ThreadPoolExecutor
-import traceback
-import time
-import sys
-
-
-def try_download(url, name):
-    aria_cmd = f"aria2c -x16 -s16 -k1M -j5 --file-allocation=none -o {name}.tar.gz '{url}'"
-    print(f"  Trying download: {url}")
-    result = subprocess.run(aria_cmd, shell=True)
-    if result.returncode == 0:
-        return True
-    print(f"  Download failed, retrying in 10 seconds...")
-    time.sleep(10)
-    result = subprocess.run(aria_cmd, shell=True)
-    return result.returncode == 0
-
-
-def sync_project(task):
-    name, path, url, strip, rev, linkfiles, copyfiles = task
-    if path not in ["./", "."]:
-        os.makedirs(path, exist_ok=True)
-    print(f"Syncing: {name} -> {path}")
-    print(f"  Download URL: {url}")
-    try:
-        downloaded = False
-        # Only apply deprecated fallback for googlesource URLs
-        if "googlesource.com" in url:
-            downloaded = try_download(url, name)
-            if not downloaded:
-                if "+archive/" in url:
-                    parts = url.split("+archive/")
-                    branch = parts[1].split(".tar.gz")[0]
-                    dep_url = f"{parts[0]}+archive/deprecated/{branch}.tar.gz"
-                    print(f"  Main branch failed, trying deprecated branch: {dep_url}")
-                    downloaded = try_download(dep_url, name)
-        else:
-            downloaded = try_download(url, name)
-
-        if not downloaded:
-            print(f"Failed to download {name} from all attempted URLs.")
-            return False
-
-        nproc = int(subprocess.check_output("nproc", shell=True).strip() or 1)
-        tar_cmd = f"tar -I 'pigz -p {nproc} -b 256' -x --record-size=1M -C {path} {strip} -f {name}.tar.gz"
-        subprocess.run(tar_cmd, shell=True, check=True)
-        os.remove(f"{name}.tar.gz")
-
-        top_dir = os.getcwd()
-        for src_rel, dest_rel in linkfiles:
-            src_path = os.path.join(top_dir, path, src_rel)
-            dest_path = os.path.join(top_dir, dest_rel)
-            os.makedirs(os.path.dirname(dest_path), exist_ok=True)
-            if os.path.lexists(dest_path):
-                os.remove(dest_path)
-            rel_target = os.path.relpath(src_path, os.path.dirname(dest_path))
-            os.symlink(rel_target, dest_path)
-            print(f"  [Link] {dest_rel} -> {src_rel}")
-        for src_rel, dest_rel in copyfiles:
-            src_path = os.path.join(top_dir, path, src_rel)
-            dest_path = os.path.join(top_dir, dest_rel)
-            os.makedirs(os.path.dirname(dest_path), exist_ok=True)
-            shutil.copy2(src_path, dest_path)
-            print(f"  [Copy] {dest_rel} from {src_rel}")
-        print(f"Synced {name} successfully!")
-        return True
-    except Exception as e:
-        print(f"Failed to sync {name}: {e}")
-        traceback.print_exc()
-        return False
-
-
-def main(manifest_path='manifest.xml'):
-    if not os.path.exists(manifest_path):
-        print(f"ERROR: manifest file not found: {manifest_path}")
-        return 2
-
-    with open(manifest_path, 'r') as f:
-        manifest_content = f.read()
-    root = ET.fromstring(manifest_content)
-
-    remotes = {}
-    for r in root.findall('remote'):
-        fetch = (r.get('fetch') or '').rstrip('/')
-        if fetch == '..':
-            fetch = 'https://android.googlesource.com'
-        remotes[r.get('name')] = fetch
-    default = root.find('default')
-    def_remote = default.get('remote') if default is not None else None
-    def_rev = default.get('revision') if default is not None else None
-
-    sync_tasks = []
-    for project in root.findall('project'):
-        name = project.get('name')
-        path = project.get('path', name)
-        remote_name = project.get('remote', def_remote)
-        rev = project.get('revision', def_rev)
-        base_url = remotes.get(remote_name)
-        if not base_url:
-            continue
-        if "github.com" in base_url:
-            url = f"{base_url}/{name}/archive/{rev}.tar.gz"
-            strip = "--strip-components=1"
-        elif "googlesource.com" in base_url:
-            url = f"{base_url}/{name}/+archive/{rev}.tar.gz"
-            strip = ""
-        elif "git.codelinaro.org" in base_url:
-            url = f"{base_url}/{name}/-/archive/{rev}.tar.gz"
-            strip = "--strip-components=1"
-        else:
-            continue
-        linkfiles = [(lf.get('src'), lf.get('dest')) for lf in project.findall('linkfile')]
-        copyfiles = [(cf.get('src'), cf.get('dest')) for cf in project.findall('copyfile')]
-        sync_tasks.append((name, path, url, strip, rev, linkfiles, copyfiles))
-
-    print(f"Found {len(sync_tasks)} projects to sync.")
-
-    max_workers = (os.cpu_count() or 2) * 4
-    with ThreadPoolExecutor(max_workers=max_workers) as executor:
-        results = list(executor.map(sync_project, sync_tasks))
-
-    if not all(results):
-        print("One or more projects failed to sync!")
-        return 1
-    return 0
-
-
-if __name__ == '__main__':
-    rc = main()
-    sys.exit(rc)

.github/actions/networking/patches/bbrv3-android14-6.1.patch

@@ -1,2744 +0,0 @@
-diff --git a/include/net/tcp.h b/include/net/tcp.h
-index afe1ca2cc01a..2b7b8225e927 100644
---- a/include/net/tcp.h
-+++ b/include/net/tcp.h
-@@ -382,6 +382,12 @@ static inline void tcp_dec_quickack_mode(struct sock *sk)
- #define	TCP_ECN_QUEUE_CWR	2
- #define	TCP_ECN_DEMAND_CWR	4
- #define	TCP_ECN_SEEN		8
-+#define	TCP_ECN_LOW		128
-+
-+/* PLB (Protective Load Balancing) - stub for kernels without PLB support */
-+struct tcp_plb_state {
-+	/* empty: PLB not supported */
-+};
- 
- enum tcp_tw_status {
- 	TCP_TW_SUCCESS = 0,
-diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
-index 50655de04c9b..82f8bd8f0d16 100644
---- a/include/uapi/linux/inet_diag.h
-+++ b/include/uapi/linux/inet_diag.h
-@@ -229,6 +229,29 @@ struct tcp_bbr_info {
- 	__u32	bbr_min_rtt;		/* min-filtered RTT in uSec */
- 	__u32	bbr_pacing_gain;	/* pacing gain shifted left 8 bits */
- 	__u32	bbr_cwnd_gain;		/* cwnd gain shifted left 8 bits */
-+	__u32	bbr_bw_hi_lsb;		/* lower 32 bits of bw_hi */
-+	__u32	bbr_bw_hi_msb;		/* upper 32 bits of bw_hi */
-+	__u32	bbr_bw_lo_lsb;		/* lower 32 bits of bw_lo */
-+	__u32	bbr_bw_lo_msb;		/* upper 32 bits of bw_lo */
-+	__u8	bbr_mode;		/* current bbr_mode in state machine */
-+	__u8	bbr_phase;		/* current state machine phase */
-+	__u8	unused1;		/* alignment padding; not used yet */
-+	__u8	bbr_version;		/* BBR algorithm version */
-+	__u32	bbr_inflight_lo;	/* lower short-term data volume bound */
-+	__u32	bbr_inflight_hi;	/* higher long-term data volume bound */
-+	__u32	bbr_extra_acked;	/* max excess packets ACKed in epoch */
-+};
-+
-+/* TCP BBR congestion control bbr_phase as reported in netlink/ss stats. */
-+enum tcp_bbr_phase {
-+	BBR_PHASE_INVALID		= 0,
-+	BBR_PHASE_STARTUP		= 1,
-+	BBR_PHASE_DRAIN			= 2,
-+	BBR_PHASE_PROBE_RTT		= 3,
-+	BBR_PHASE_PROBE_BW_UP		= 4,
-+	BBR_PHASE_PROBE_BW_DOWN		= 5,
-+	BBR_PHASE_PROBE_BW_CRUISE	= 6,
-+	BBR_PHASE_PROBE_BW_REFILL	= 7,
- };
- 
- union tcp_cc_info {
-diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
-index 8fc09e8638b3..b3d03f23660e 100644
---- a/include/uapi/linux/tcp.h
-+++ b/include/uapi/linux/tcp.h
-@@ -170,6 +170,7 @@ enum tcp_fastopen_client_fail {
- #define TCPI_OPT_ECN		8 /* ECN was negociated at TCP session init */
- #define TCPI_OPT_ECN_SEEN	16 /* we received at least one packet with ECT */
- #define TCPI_OPT_SYN_DATA	32 /* SYN-ACK acked data in SYN sent or rcvd */
-+#define TCPI_OPT_ECN_LOW	128 /* Low-latency ECN configured at init */
- 
- /*
-  * Sender's congestion state indicating normal or abnormal situations
-diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
-index 54eec33c6e1c..3ecfea505c76 100644
---- a/net/ipv4/tcp_bbr.c
-+++ b/net/ipv4/tcp_bbr.c
-@@ -1,18 +1,19 @@
--/* Bottleneck Bandwidth and RTT (BBR) congestion control
-+/* BBR (Bottleneck Bandwidth and RTT) congestion control
-  *
-- * BBR congestion control computes the sending rate based on the delivery
-- * rate (throughput) estimated from ACKs. In a nutshell:
-+ * BBR is a model-based congestion control algorithm that aims for low queues,
-+ * low loss, and (bounded) Reno/CUBIC coexistence. To maintain a model of the
-+ * network path, it uses measurements of bandwidth and RTT, as well as (if they
-+ * occur) packet loss and/or shallow-threshold ECN signals. Note that although
-+ * it can use ECN or loss signals explicitly, it does not require either; it
-+ * can bound its in-flight data based on its estimate of the BDP.
-  *
-- *   On each ACK, update our model of the network path:
-- *      bottleneck_bandwidth = windowed_max(delivered / elapsed, 10 round trips)
-- *      min_rtt = windowed_min(rtt, 10 seconds)
-- *   pacing_rate = pacing_gain * bottleneck_bandwidth
-- *   cwnd = max(cwnd_gain * bottleneck_bandwidth * min_rtt, 4)
-- *
-- * The core algorithm does not react directly to packet losses or delays,
-- * although BBR may adjust the size of next send per ACK when loss is
-- * observed, or adjust the sending rate if it estimates there is a
-- * traffic policer, in order to keep the drop rate reasonable.
-+ * The model has both higher and lower bounds for the operating range:
-+ *   lo: bw_lo, inflight_lo: conservative short-term lower bound
-+ *   hi: bw_hi, inflight_hi: robust long-term upper bound
-+ * The bandwidth-probing time scale is (a) extended dynamically based on
-+ * estimated BDP to improve coexistence with Reno/CUBIC; (b) bounded by
-+ * an interactive wall-clock time-scale to be more scalable and responsive
-+ * than Reno and CUBIC.
-  *
-  * Here is a state transition diagram for BBR:
-  *
-@@ -65,6 +66,13 @@
- #include <linux/random.h>
- #include <linux/win_minmax.h>
- 
-+#include <trace/events/tcp.h>
-+#include "tcp_dctcp.h"
-+
-+#define BBR_VERSION		3
-+
-+#define bbr_param(sk,name)	(bbr_ ## name)
-+
- /* Scale factor for rate in pkt/uSec unit to avoid truncation in bandwidth
-  * estimation. The rate unit ~= (1500 bytes / 1 usec / 2^24) ~= 715 bps.
-  * This handles bandwidths from 0.06pps (715bps) to 256Mpps (3Tbps) in a u32.
-@@ -85,36 +93,41 @@ enum bbr_mode {
- 	BBR_PROBE_RTT,	/* cut inflight to min to probe min_rtt */
- };
- 
-+/* How does the incoming ACK stream relate to our bandwidth probing? */
-+enum bbr_ack_phase {
-+	BBR_ACKS_INIT,		  /* not probing; not getting probe feedback */
-+	BBR_ACKS_REFILLING,	  /* sending at est. bw to fill pipe */
-+	BBR_ACKS_PROBE_STARTING,  /* inflight rising to probe bw */
-+	BBR_ACKS_PROBE_FEEDBACK,  /* getting feedback from bw probing */
-+	BBR_ACKS_PROBE_STOPPING,  /* stopped probing; still getting feedback */
-+};
-+
- /* BBR congestion control block */
- struct bbr {
- 	u32	min_rtt_us;	        /* min RTT in min_rtt_win_sec window */
- 	u32	min_rtt_stamp;	        /* timestamp of min_rtt_us */
- 	u32	probe_rtt_done_stamp;   /* end time for BBR_PROBE_RTT mode */
--	struct minmax bw;	/* Max recent delivery rate in pkts/uS << 24 */
--	u32	rtt_cnt;	    /* count of packet-timed rounds elapsed */
-+	u32	probe_rtt_min_us;	/* min RTT in probe_rtt_win_ms win */
-+	u32	probe_rtt_min_stamp;	/* timestamp of probe_rtt_min_us*/
- 	u32     next_rtt_delivered; /* scb->tx.delivered at end of round */
- 	u64	cycle_mstamp;	     /* time of this cycle phase start */
--	u32     mode:3,		     /* current bbr_mode in state machine */
-+	u32     mode:2,		     /* current bbr_mode in state machine */
- 		prev_ca_state:3,     /* CA state on previous ACK */
--		packet_conservation:1,  /* use packet conservation? */
- 		round_start:1,	     /* start of packet-timed tx->ack round? */
-+		ce_state:1,          /* If most recent data has CE bit set */
-+		bw_probe_up_rounds:5,   /* cwnd-limited rounds in PROBE_UP */
-+		try_fast_path:1,	/* can we take fast path? */
- 		idle_restart:1,	     /* restarting after idle? */
- 		probe_rtt_round_done:1,  /* a BBR_PROBE_RTT round at 4 pkts? */
--		unused:13,
--		lt_is_sampling:1,    /* taking long-term ("LT") samples now? */
--		lt_rtt_cnt:7,	     /* round trips in long-term interval */
--		lt_use_bw:1;	     /* use lt_bw as our bw estimate? */
--	u32	lt_bw;		     /* LT est delivery rate in pkts/uS << 24 */
--	u32	lt_last_delivered;   /* LT intvl start: tp->delivered */
--	u32	lt_last_stamp;	     /* LT intvl start: tp->delivered_mstamp */
--	u32	lt_last_lost;	     /* LT intvl start: tp->lost */
-+		init_cwnd:7,         /* initial cwnd */
-+		unused_1:10;
- 	u32	pacing_gain:10,	/* current gain for setting pacing rate */
- 		cwnd_gain:10,	/* current gain for setting cwnd */
- 		full_bw_reached:1,   /* reached full bw in Startup? */
- 		full_bw_cnt:2,	/* number of rounds without large bw gains */
--		cycle_idx:3,	/* current index in pacing_gain cycle array */
-+		cycle_idx:2,	/* current index in pacing_gain cycle array */
- 		has_seen_rtt:1, /* have we seen an RTT sample yet? */
--		unused_b:5;
-+		unused_2:6;
- 	u32	prior_cwnd;	/* prior cwnd upon entering loss recovery */
- 	u32	full_bw;	/* recent bw, to estimate if pipe is full */
- 
-@@ -124,19 +137,67 @@ struct bbr {
- 	u32	ack_epoch_acked:20,	/* packets (S)ACKed in sampling epoch */
- 		extra_acked_win_rtts:5,	/* age of extra_acked, in round trips */
- 		extra_acked_win_idx:1,	/* current index in extra_acked array */
--		unused_c:6;
-+	/* BBR v3 state: */
-+		full_bw_now:1,		/* recently reached full bw plateau? */
-+		startup_ecn_rounds:2,	/* consecutive hi ECN STARTUP rounds */
-+		loss_in_cycle:1,	/* packet loss in this cycle? */
-+		ecn_in_cycle:1,		/* ECN in this cycle? */
-+		unused_3:1;
-+	u32	loss_round_delivered; /* scb->tx.delivered ending loss round */
-+	u32	undo_bw_lo;	     /* bw_lo before latest losses */
-+	u32	undo_inflight_lo;    /* inflight_lo before latest losses */
-+	u32	undo_inflight_hi;    /* inflight_hi before latest losses */
-+	u32	bw_latest;	 /* max delivered bw in last round trip */
-+	u32	bw_lo;		 /* lower bound on sending bandwidth */
-+	u32	bw_hi[2];	 /* max recent measured bw sample */
-+	u32	inflight_latest; /* max delivered data in last round trip */
-+	u32	inflight_lo;	 /* lower bound of inflight data range */
-+	u32	inflight_hi;	 /* upper bound of inflight data range */
-+	u32	bw_probe_up_cnt; /* packets delivered per inflight_hi incr */
-+	u32	bw_probe_up_acks;  /* packets (S)ACKed since inflight_hi incr */
-+	u32	probe_wait_us;	 /* PROBE_DOWN until next clock-driven probe */
-+	u32	prior_rcv_nxt;	/* tp->rcv_nxt when CE state last changed */
-+	u32	ecn_eligible:1,	/* sender can use ECN (RTT, handshake)? */
-+		ecn_alpha:9,	/* EWMA delivered_ce/delivered; 0..256 */
-+		bw_probe_samples:1,    /* rate samples reflect bw probing? */
-+		prev_probe_too_high:1, /* did last PROBE_UP go too high? */
-+		stopped_risky_probe:1, /* last PROBE_UP stopped due to risk? */
-+		rounds_since_probe:8,  /* packet-timed rounds since probed bw */
-+		loss_round_start:1,    /* loss_round_delivered round trip? */
-+		loss_in_round:1,       /* loss marked in this round trip? */
-+		ecn_in_round:1,	       /* ECN marked in this round trip? */
-+		ack_phase:3,	       /* bbr_ack_phase: meaning of ACKs */
-+		loss_events_in_round:4,/* losses in STARTUP round */
-+		initialized:1;	       /* has bbr_init() been called? */
-+	u32	alpha_last_delivered;	 /* tp->delivered    at alpha update */
-+	u32	alpha_last_delivered_ce; /* tp->delivered_ce at alpha update */
-+
-+	u8	unused_4;		/* to preserve alignment */
-+	struct tcp_plb_state plb;
- };
- 
--#define CYCLE_LEN	8	/* number of phases in a pacing gain cycle */
-+struct bbr_context {
-+	u32 sample_bw;
-+};
- 
--/* Window length of bw filter (in rounds): */
--static const int bbr_bw_rtts = CYCLE_LEN + 2;
- /* Window length of min_rtt filter (in sec): */
- static const u32 bbr_min_rtt_win_sec = 10;
- /* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode: */
- static const u32 bbr_probe_rtt_mode_ms = 200;
--/* Skip TSO below the following bandwidth (bits/sec): */
--static const int bbr_min_tso_rate = 1200000;
-+/* Window length of probe_rtt_min_us filter (in ms), and consequently the
-+ * typical interval between PROBE_RTT mode entries. The default is 5000ms.
-+ * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC
-+ */
-+static const u32 bbr_probe_rtt_win_ms = 5000;
-+/* Proportion of cwnd to estimated BDP in PROBE_RTT, in units of BBR_UNIT: */
-+static const u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2;
-+
-+/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting
-+ * in bigger TSO bursts. We cut the RTT-based allowance in half
-+ * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance
-+ * is below 1500 bytes after 6 * ~500 usec = 3ms.
-+ */
-+static const u32 bbr_tso_rtt_shift = 9;
- 
- /* Pace at ~1% below estimated bw, on average, to reduce queue at bottleneck.
-  * In order to help drive the network toward lower queues and low latency while
-@@ -146,13 +207,15 @@ static const int bbr_min_tso_rate = 1200000;
-  */
- static const int bbr_pacing_margin_percent = 1;
- 
--/* We use a high_gain value of 2/ln(2) because it's the smallest pacing gain
-+/* We use a startup_pacing_gain of 4*ln(2) because it's the smallest value
-  * that will allow a smoothly increasing pacing rate that will double each RTT
-  * and send the same number of packets per RTT that an un-paced, slow-starting
-  * Reno or CUBIC flow would:
-  */
--static const int bbr_high_gain  = BBR_UNIT * 2885 / 1000 + 1;
--/* The pacing gain of 1/high_gain in BBR_DRAIN is calculated to typically drain
-+static const int bbr_startup_pacing_gain = BBR_UNIT * 277 / 100 + 1;
-+/* The gain for deriving startup cwnd: */
-+static const int bbr_startup_cwnd_gain = BBR_UNIT * 2;
-+/* The pacing gain in BBR_DRAIN is calculated to typically drain
-  * the queue created in BBR_STARTUP in a single round:
-  */
- static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885;
-@@ -160,13 +223,17 @@ static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885;
- static const int bbr_cwnd_gain  = BBR_UNIT * 2;
- /* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw: */
- static const int bbr_pacing_gain[] = {
--	BBR_UNIT * 5 / 4,	/* probe for more available bw */
--	BBR_UNIT * 3 / 4,	/* drain queue and/or yield bw to other flows */
--	BBR_UNIT, BBR_UNIT, BBR_UNIT,	/* cruise at 1.0*bw to utilize pipe, */
--	BBR_UNIT, BBR_UNIT, BBR_UNIT	/* without creating excess queue... */
-+	BBR_UNIT * 5 / 4,	/* UP: probe for more available bw */
-+	BBR_UNIT * 91 / 100,	/* DOWN: drain queue and/or yield bw */
-+	BBR_UNIT,		/* CRUISE: try to use pipe w/ some headroom */
-+	BBR_UNIT,		/* REFILL: refill pipe to estimated 100% */
-+};
-+enum bbr_pacing_gain_phase {
-+	BBR_BW_PROBE_UP		= 0,  /* push up inflight to probe for bw/vol */
-+	BBR_BW_PROBE_DOWN	= 1,  /* drain excess inflight from the queue */
-+	BBR_BW_PROBE_CRUISE	= 2,  /* use pipe, w/ headroom in queue/pipe */
-+	BBR_BW_PROBE_REFILL	= 3,  /* refill the pipe again to 100% */
- };
--/* Randomize the starting gain cycling phase over N phases: */
--static const u32 bbr_cycle_rand = 7;
- 
- /* Try to keep at least this many packets in flight, if things go smoothly. For
-  * smooth functioning, a sliding window protocol ACKing every other packet
-@@ -174,24 +241,12 @@ static const u32 bbr_cycle_rand = 7;
-  */
- static const u32 bbr_cwnd_min_target = 4;
- 
--/* To estimate if BBR_STARTUP mode (i.e. high_gain) has filled pipe... */
-+/* To estimate if BBR_STARTUP or BBR_BW_PROBE_UP has filled pipe... */
- /* If bw has increased significantly (1.25x), there may be more bw available: */
- static const u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4;
- /* But after 3 rounds w/o significant bw growth, estimate pipe is full: */
- static const u32 bbr_full_bw_cnt = 3;
- 
--/* "long-term" ("LT") bandwidth estimator parameters... */
--/* The minimum number of rounds in an LT bw sampling interval: */
--static const u32 bbr_lt_intvl_min_rtts = 4;
--/* If lost/delivered ratio > 20%, interval is "lossy" and we may be policed: */
--static const u32 bbr_lt_loss_thresh = 50;
--/* If 2 intervals have a bw ratio <= 1/8, their bw is "consistent": */
--static const u32 bbr_lt_bw_ratio = BBR_UNIT / 8;
--/* If 2 intervals have a bw diff <= 4 Kbit/sec their bw is "consistent": */
--static const u32 bbr_lt_bw_diff = 4000 / 8;
--/* If we estimate we're policed, use lt_bw for this many round trips: */
--static const u32 bbr_lt_bw_max_rtts = 48;
--
- /* Gain factor for adding extra_acked to target cwnd: */
- static const int bbr_extra_acked_gain = BBR_UNIT;
- /* Window length of extra_acked window. */
-@@ -201,8 +256,121 @@ static const u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20;
- /* Time period for clamping cwnd increment due to ack aggregation */
- static const u32 bbr_extra_acked_max_us = 100 * 1000;
- 
-+/* Flags to control BBR ECN-related behavior... */
-+
-+/* Ensure ACKs only ACK packets with consistent ECN CE status? */
-+static const bool bbr_precise_ece_ack = true;
-+
-+/* Max RTT (in usec) at which to use sender-side ECN logic.
-+ * Disabled when 0 (ECN allowed at any RTT).
-+ */
-+static const u32 bbr_ecn_max_rtt_us = 5000;
-+
-+/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE.
-+ * No loss response when 0.
-+ */
-+static const u32 bbr_beta = BBR_UNIT * 30 / 100;
-+
-+/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE (1/16 = 6.25%) */
-+static const u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16;
-+
-+/* The initial value for ecn_alpha; 1.0 allows a flow to respond quickly
-+ * to congestion if the bottleneck is congested when the flow starts up.
-+ */
-+static const u32 bbr_ecn_alpha_init = BBR_UNIT;
-+
-+/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE.
-+ * No ECN based bounding when 0.
-+ */
-+static const u32 bbr_ecn_factor = BBR_UNIT * 1 / 3;	 /* 1/3 = 33% */
-+
-+/* Estimate bw probing has gone too far if CE ratio exceeds this threshold.
-+ * Scaled by BBR_SCALE. Disabled when 0.
-+ */
-+static const u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2;  /* 1/2 = 50% */
-+
-+/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN
-+ * clears then make the first round's increment to inflight_hi the following
-+ * fraction of inflight_hi.
-+ */
-+static const u32 bbr_ecn_reprobe_gain = BBR_UNIT * 1 / 2;
-+
-+/* Estimate bw probing has gone too far if loss rate exceeds this level. */
-+static const u32 bbr_loss_thresh = BBR_UNIT * 2 / 100;  /* 2% loss */
-+
-+/* Slow down for a packet loss recovered by TLP? */
-+static const bool bbr_loss_probe_recovery = true;
-+
-+/* Exit STARTUP if number of loss marking events in a Recovery round is >= N,
-+ * and loss rate is higher than bbr_loss_thresh.
-+ * Disabled if 0.
-+ */
-+static const u32 bbr_full_loss_cnt = 6;
-+
-+/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh
-+ * meets this count.
-+ */
-+static const u32 bbr_full_ecn_cnt = 2;
-+
-+/* Fraction of unutilized headroom to try to leave in path upon high loss. */
-+static const u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100;
-+
-+/* How much do we increase cwnd_gain when probing for bandwidth in
-+ * BBR_BW_PROBE_UP? This specifies the increment in units of
-+ * BBR_UNIT/4. The default is 1, meaning 0.25.
-+ * The min value is 0 (meaning 0.0); max is 3 (meaning 0.75).
-+ */
-+static const u32 bbr_bw_probe_cwnd_gain = 1;
-+
-+/* Max number of packet-timed rounds to wait before probing for bandwidth.  If
-+ * we want to tolerate 1% random loss per round, and not have this cut our
-+ * inflight too much, we must probe for bw periodically on roughly this scale.
-+ * If low, limits Reno/CUBIC coexistence; if high, limits loss tolerance.
-+ * We aim to be fair with Reno/CUBIC up to a BDP of at least:
-+ *  BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets
-+ */
-+static const u32 bbr_bw_probe_max_rounds = 63;
-+
-+/* Max amount of randomness to inject in round counting for Reno-coexistence.
-+ */
-+static const u32 bbr_bw_probe_rand_rounds = 2;
-+
-+/* Use BBR-native probe time scale starting at this many usec.
-+ * We aim to be fair with Reno/CUBIC up to an inter-loss time epoch of at least:
-+ *  BDP*RTT = 25Mbps * .030sec /(1514bytes) * 0.030sec = 1.9 secs
-+ */
-+static const u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC;  /* 2 secs */
-+
-+/* Use BBR-native probes spread over this many usec: */
-+static const u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC;  /* 1 secs */
-+
-+/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */
-+static const bool bbr_fast_path = true;
-+
-+/* Use fast ack mode? */
-+static const bool bbr_fast_ack_mode = true;
-+
-+static u32 bbr_max_bw(const struct sock *sk);
-+static u32 bbr_bw(const struct sock *sk);
-+static void bbr_exit_probe_rtt(struct sock *sk);
-+static void bbr_reset_congestion_signals(struct sock *sk);
-+static void bbr_run_loss_probe_recovery(struct sock *sk);
-+
- static void bbr_check_probe_rtt_done(struct sock *sk);
- 
-+/* This connection can use ECN if both endpoints have signaled ECN support in
-+ * the handshake and the per-route settings indicated this is a
-+ * shallow-threshold ECN environment, meaning both:
-+ *  (a) ECN CE marks indicate low-latency/shallow-threshold congestion, and
-+ *  (b) TCP endpoints provide precise ACKs that only ACK data segments
-+ *      with consistent ECN CE status
-+ */
-+static bool bbr_can_use_ecn(const struct sock *sk)
-+{
-+	return (tcp_sk(sk)->ecn_flags & TCP_ECN_OK) &&
-+	       (tcp_sk(sk)->ecn_flags & TCP_ECN_LOW);
-+}
-+
- /* Do we estimate that STARTUP filled the pipe? */
- static bool bbr_full_bw_reached(const struct sock *sk)
- {
-@@ -214,17 +382,17 @@ static bool bbr_full_bw_reached(const struct sock *sk)
- /* Return the windowed max recent bandwidth sample, in pkts/uS << BW_SCALE. */
- static u32 bbr_max_bw(const struct sock *sk)
- {
--	struct bbr *bbr = inet_csk_ca(sk);
-+	const struct bbr *bbr = inet_csk_ca(sk);
- 
--	return minmax_get(&bbr->bw);
-+	return max(bbr->bw_hi[0], bbr->bw_hi[1]);
- }
- 
- /* Return the estimated bandwidth of the path, in pkts/uS << BW_SCALE. */
- static u32 bbr_bw(const struct sock *sk)
- {
--	struct bbr *bbr = inet_csk_ca(sk);
-+	const struct bbr *bbr = inet_csk_ca(sk);
- 
--	return bbr->lt_use_bw ? bbr->lt_bw : bbr_max_bw(sk);
-+	return min(bbr_max_bw(sk), bbr->bw_lo);
- }
- 
- /* Return maximum extra acked in past k-2k round trips,
-@@ -241,15 +409,23 @@ static u16 bbr_extra_acked(const struct sock *sk)
-  * The order here is chosen carefully to avoid overflow of u64. This should
-  * work for input rates of up to 2.9Tbit/sec and gain of 2.89x.
-  */
--static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain)
-+static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain,
-+				  int margin)
- {
- 	unsigned int mss = tcp_sk(sk)->mss_cache;
- 
- 	rate *= mss;
- 	rate *= gain;
- 	rate >>= BBR_SCALE;
--	rate *= USEC_PER_SEC / 100 * (100 - bbr_pacing_margin_percent);
--	return rate >> BW_SCALE;
-+	rate *= USEC_PER_SEC / 100 * (100 - margin);
-+	rate >>= BW_SCALE;
-+	rate = max(rate, 1ULL);
-+	return rate;
-+}
-+
-+static u64 bbr_bw_bytes_per_sec(struct sock *sk, u64 rate)
-+{
-+	return bbr_rate_bytes_per_sec(sk, rate, BBR_UNIT, 0);
- }
- 
- /* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */
-@@ -257,12 +433,13 @@ static unsigned long bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain)
- {
- 	u64 rate = bw;
- 
--	rate = bbr_rate_bytes_per_sec(sk, rate, gain);
--	rate = min_t(u64, rate, sk->sk_max_pacing_rate);
-+	rate = bbr_rate_bytes_per_sec(sk, rate, gain,
-+				      bbr_pacing_margin_percent);
-+	rate = min_t(u64, rate, READ_ONCE(sk->sk_max_pacing_rate));
- 	return rate;
- }
- 
--/* Initialize pacing rate to: high_gain * init_cwnd / RTT. */
-+/* Initialize pacing rate to: startup_pacing_gain * init_cwnd / RTT. */
- static void bbr_init_pacing_rate_from_rtt(struct sock *sk)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
-@@ -278,7 +455,9 @@ static void bbr_init_pacing_rate_from_rtt(struct sock *sk)
- 	}
- 	bw = (u64)tcp_snd_cwnd(tp) * BW_UNIT;
- 	do_div(bw, rtt_us);
--	sk->sk_pacing_rate = bbr_bw_to_pacing_rate(sk, bw, bbr_high_gain);
-+	WRITE_ONCE(sk->sk_pacing_rate,
-+		   bbr_bw_to_pacing_rate(sk, bw,
-+					 bbr_param(sk, startup_pacing_gain)));
- }
- 
- /* Pace using current bw estimate and a gain factor. */
-@@ -290,30 +469,52 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
- 
- 	if (unlikely(!bbr->has_seen_rtt && tp->srtt_us))
- 		bbr_init_pacing_rate_from_rtt(sk);
--	if (bbr_full_bw_reached(sk) || rate > sk->sk_pacing_rate)
--		sk->sk_pacing_rate = rate;
-+	if (bbr_full_bw_reached(sk) || rate > READ_ONCE(sk->sk_pacing_rate))
-+		WRITE_ONCE(sk->sk_pacing_rate, rate);
-+}
-+
-+/* Return the number of segments BBR would like in a TSO/GSO skb, given a
-+ * particular max gso size as a constraint. TODO: make this simpler and more
-+ * consistent by switching bbr to just call tcp_tso_autosize().
-+ */
-+static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now,
-+				u32 gso_max_size)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 segs, r;
-+	u64 bytes;
-+
-+	/* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */
-+	bytes = READ_ONCE(sk->sk_pacing_rate) >> READ_ONCE(sk->sk_pacing_shift);
-+
-+	/* Budget a TSO/GSO burst size allowance based on min_rtt. For every
-+	 * K = 2^tso_rtt_shift microseconds of min_rtt, halve the burst.
-+	 * The min_rtt-based burst allowance is: 64 KBytes / 2^(min_rtt/K)
-+	 */
-+	if (bbr_param(sk, tso_rtt_shift)) {
-+		r = bbr->min_rtt_us >> bbr_param(sk, tso_rtt_shift);
-+		if (r < BITS_PER_TYPE(u32))   /* prevent undefined behavior */
-+			bytes += GSO_LEGACY_MAX_SIZE >> r;
-+	}
-+
-+	bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER);
-+	segs = max_t(u32, bytes / mss_now,
-+		     sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs);
-+	return segs;
- }
- 
--/* override sysctl_tcp_min_tso_segs */
--static u32 bbr_min_tso_segs(struct sock *sk)
-+/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */
-+static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now)
- {
--	return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2;
-+	return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size);
- }
- 
-+/* Like bbr_t
- static u32 bbr_tso_segs_goal(struct sock *sk)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
--	u32 segs, bytes;
--
--	/* Sort of tcp_tso_autosize() but ignoring
--	 * driver provided sk_gso_max_size.
--	 */
--	bytes = min_t(unsigned long,
--		      sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift),
--		      GSO_LEGACY_MAX_SIZE - 1 - MAX_TCP_HEADER);
--	segs = max_t(u32, bytes / tp->mss_cache, bbr_min_tso_segs(sk));
- 
--	return min(segs, 0x7FU);
-+	return  bbr_tso_segs_generic(sk, tp->mss_cache, GSO_LEGACY_MAX_SIZE);
- }
- 
- /* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */
-@@ -333,7 +534,9 @@ static void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event)
- 	struct tcp_sock *tp = tcp_sk(sk);
- 	struct bbr *bbr = inet_csk_ca(sk);
- 
--	if (event == CA_EVENT_TX_START && tp->app_limited) {
-+	if (event == CA_EVENT_TX_START) {
-+		if (!tp->app_limited)
-+			return;
- 		bbr->idle_restart = 1;
- 		bbr->ack_epoch_mstamp = tp->tcp_mstamp;
- 		bbr->ack_epoch_acked = 0;
-@@ -344,6 +547,16 @@ static void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event)
- 			bbr_set_pacing_rate(sk, bbr_bw(sk), BBR_UNIT);
- 		else if (bbr->mode == BBR_PROBE_RTT)
- 			bbr_check_probe_rtt_done(sk);
-+	} else if ((event == CA_EVENT_ECN_IS_CE ||
-+		    event == CA_EVENT_ECN_NO_CE) &&
-+		   bbr_can_use_ecn(sk) &&
-+		   bbr_param(sk, precise_ece_ack)) {
-+		u32 state = bbr->ce_state;
-+		dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state);
-+		bbr->ce_state = state;
-+	} else if (event == CA_EVENT_TLP_RECOVERY &&
-+		   bbr_param(sk, loss_probe_recovery)) {
-+		bbr_run_loss_probe_recovery(sk);
- 	}
- }
- 
-@@ -366,10 +579,10 @@ static u32 bbr_bdp(struct sock *sk, u32 bw, int gain)
- 	 * default. This should only happen when the connection is not using TCP
- 	 * timestamps and has retransmitted all of the SYN/SYNACK/data packets
- 	 * ACKed so far. In this case, an RTO can cut cwnd to 1, in which
--	 * case we need to slow-start up toward something safe: TCP_INIT_CWND.
-+	 * case we need to slow-start up toward something safe: initial cwnd.
- 	 */
- 	if (unlikely(bbr->min_rtt_us == ~0U))	 /* no valid RTT samples yet? */
--		return TCP_INIT_CWND;  /* be safe: cap at default initial cwnd*/
-+		return bbr->init_cwnd;  /* be safe: cap at initial cwnd */
- 
- 	w = (u64)bw * bbr->min_rtt_us;
- 
-@@ -386,23 +599,23 @@ static u32 bbr_bdp(struct sock *sk, u32 bw, int gain)
-  *   - one skb in sending host Qdisc,
-  *   - one skb in sending host TSO/GSO engine
-  *   - one skb being received by receiver host LRO/GRO/delayed-ACK engine
-- * Don't worry, at low rates (bbr_min_tso_rate) this won't bloat cwnd because
-- * in such cases tso_segs_goal is 1. The minimum cwnd is 4 packets,
-+ * Don't worry, at low rates this won't bloat cwnd because
-+ * in such cases tso_segs_goal is small. The minimum cwnd is 4 packets,
-  * which allows 2 outstanding 2-packet sequences, to try to keep pipe
-  * full even with ACK-every-other-packet delayed ACKs.
-  */
- static u32 bbr_quantization_budget(struct sock *sk, u32 cwnd)
- {
- 	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 tso_segs_goal;
- 
--	/* Allow enough full-sized skbs in flight to utilize end systems. */
--	cwnd += 3 * bbr_tso_segs_goal(sk);
--
--	/* Reduce delayed ACKs by rounding up cwnd to the next even number. */
--	cwnd = (cwnd + 1) & ~1U;
-+	tso_segs_goal = 3 * bbr_tso_segs_goal(sk);
- 
-+	/* Allow enough full-sized skbs in flight to utilize end systems. */
-+	cwnd = max_t(u32, cwnd, tso_segs_goal);
-+	cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target));
- 	/* Ensure gain cycling gets inflight above BDP even for small BDPs. */
--	if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == 0)
-+	if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP)
- 		cwnd += 2;
- 
- 	return cwnd;
-@@ -457,10 +670,10 @@ static u32 bbr_ack_aggregation_cwnd(struct sock *sk)
- {
- 	u32 max_aggr_cwnd, aggr_cwnd = 0;
- 
--	if (bbr_extra_acked_gain && bbr_full_bw_reached(sk)) {
-+	if (bbr_param(sk, extra_acked_gain)) {
- 		max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us)
- 				/ BW_UNIT;
--		aggr_cwnd = (bbr_extra_acked_gain * bbr_extra_acked(sk))
-+		aggr_cwnd = (bbr_param(sk, extra_acked_gain) * bbr_extra_acked(sk))
- 			     >> BBR_SCALE;
- 		aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd);
- 	}
-@@ -468,66 +681,27 @@ static u32 bbr_ack_aggregation_cwnd(struct sock *sk)
- 	return aggr_cwnd;
- }
- 
--/* An optimization in BBR to reduce losses: On the first round of recovery, we
-- * follow the packet conservation principle: send P packets per P packets acked.
-- * After that, we slow-start and send at most 2*P packets per P packets acked.
-- * After recovery finishes, or upon undo, we restore the cwnd we had when
-- * recovery started (capped by the target cwnd based on estimated BDP).
-- *
-- * TODO(ycheng/ncardwell): implement a rate-based approach.
-- */
--static bool bbr_set_cwnd_to_recover_or_restore(
--	struct sock *sk, const struct rate_sample *rs, u32 acked, u32 *new_cwnd)
-+/* Returns the cwnd for PROBE_RTT mode. */
-+static u32 bbr_probe_rtt_cwnd(struct sock *sk)
- {
--	struct tcp_sock *tp = tcp_sk(sk);
--	struct bbr *bbr = inet_csk_ca(sk);
--	u8 prev_state = bbr->prev_ca_state, state = inet_csk(sk)->icsk_ca_state;
--	u32 cwnd = tcp_snd_cwnd(tp);
--
--	/* An ACK for P pkts should release at most 2*P packets. We do this
--	 * in two steps. First, here we deduct the number of lost packets.
--	 * Then, in bbr_set_cwnd() we slow start up toward the target cwnd.
--	 */
--	if (rs->losses > 0)
--		cwnd = max_t(s32, cwnd - rs->losses, 1);
--
--	if (state == TCP_CA_Recovery && prev_state != TCP_CA_Recovery) {
--		/* Starting 1st round of Recovery, so do packet conservation. */
--		bbr->packet_conservation = 1;
--		bbr->next_rtt_delivered = tp->delivered;  /* start round now */
--		/* Cut unused cwnd from app behavior, TSQ, or TSO deferral: */
--		cwnd = tcp_packets_in_flight(tp) + acked;
--	} else if (prev_state >= TCP_CA_Recovery && state < TCP_CA_Recovery) {
--		/* Exiting loss recovery; restore cwnd saved before recovery. */
--		cwnd = max(cwnd, bbr->prior_cwnd);
--		bbr->packet_conservation = 0;
--	}
--	bbr->prev_ca_state = state;
--
--	if (bbr->packet_conservation) {
--		*new_cwnd = max(cwnd, tcp_packets_in_flight(tp) + acked);
--		return true;	/* yes, using packet conservation */
--	}
--	*new_cwnd = cwnd;
--	return false;
-+	return max_t(u32, bbr_param(sk, cwnd_min_target),
-+		     bbr_bdp(sk, bbr_bw(sk), bbr_param(sk, probe_rtt_cwnd_gain)));
- }
- 
- /* Slow-start up toward target cwnd (if bw estimate is growing, or packet loss
-  * has drawn us down below target), or snap down to target if we're above it.
-  */
- static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs,
--			 u32 acked, u32 bw, int gain)
-+			 u32 acked, u32 bw, int gain, u32 cwnd,
-+			 struct bbr_context *ctx)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
- 	struct bbr *bbr = inet_csk_ca(sk);
--	u32 cwnd = tcp_snd_cwnd(tp), target_cwnd = 0;
-+	u32 target_cwnd = 0;
- 
- 	if (!acked)
- 		goto done;  /* no packet fully ACKed; just apply caps */
- 
--	if (bbr_set_cwnd_to_recover_or_restore(sk, rs, acked, &cwnd))
--		goto done;
--
- 	target_cwnd = bbr_bdp(sk, bw, gain);
- 
- 	/* Increment the cwnd to account for excess ACKed data that seems
-@@ -536,74 +710,26 @@ static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs,
- 	target_cwnd += bbr_ack_aggregation_cwnd(sk);
- 	target_cwnd = bbr_quantization_budget(sk, target_cwnd);
- 
--	/* If we're below target cwnd, slow start cwnd toward target cwnd. */
--	if (bbr_full_bw_reached(sk))  /* only cut cwnd if we filled the pipe */
--		cwnd = min(cwnd + acked, target_cwnd);
--	else if (cwnd < target_cwnd || tp->delivered < TCP_INIT_CWND)
--		cwnd = cwnd + acked;
--	cwnd = max(cwnd, bbr_cwnd_min_target);
-+	/* Update cwnd and enable fast path if cwnd reaches target_cwnd. */
-+	bbr->try_fast_path = 0;
-+	if (bbr_full_bw_reached(sk)) { /* only cut cwnd if we filled the pipe */
-+		cwnd += acked;
-+		if (cwnd >= target_cwnd) {
-+			cwnd = target_cwnd;
-+			bbr->try_fast_path = 1;
-+		}
-+	} else if (cwnd < target_cwnd || cwnd  < 2 * bbr->init_cwnd) {
-+		cwnd += acked;
-+	} else {
-+		bbr->try_fast_path = 1;
-+	}
- 
-+	cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target));
- done:
--	tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp));	/* apply global cap */
-+	tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp));  /* global cap */
- 	if (bbr->mode == BBR_PROBE_RTT)  /* drain queue, refresh min_rtt */
--		tcp_snd_cwnd_set(tp, min(tcp_snd_cwnd(tp), bbr_cwnd_min_target));
--}
--
--/* End cycle phase if it's time and/or we hit the phase's in-flight target. */
--static bool bbr_is_next_cycle_phase(struct sock *sk,
--				    const struct rate_sample *rs)
--{
--	struct tcp_sock *tp = tcp_sk(sk);
--	struct bbr *bbr = inet_csk_ca(sk);
--	bool is_full_length =
--		tcp_stamp_us_delta(tp->delivered_mstamp, bbr->cycle_mstamp) >
--		bbr->min_rtt_us;
--	u32 inflight, bw;
--
--	/* The pacing_gain of 1.0 paces at the estimated bw to try to fully
--	 * use the pipe without increasing the queue.
--	 */
--	if (bbr->pacing_gain == BBR_UNIT)
--		return is_full_length;		/* just use wall clock time */
--
--	inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight);
--	bw = bbr_max_bw(sk);
--
--	/* A pacing_gain > 1.0 probes for bw by trying to raise inflight to at
--	 * least pacing_gain*BDP; this may take more than min_rtt if min_rtt is
--	 * small (e.g. on a LAN). We do not persist if packets are lost, since
--	 * a path with small buffers may not hold that much.
--	 */
--	if (bbr->pacing_gain > BBR_UNIT)
--		return is_full_length &&
--			(rs->losses ||  /* perhaps pacing_gain*BDP won't fit */
--			 inflight >= bbr_inflight(sk, bw, bbr->pacing_gain));
--
--	/* A pacing_gain < 1.0 tries to drain extra queue we added if bw
--	 * probing didn't find more bw. If inflight falls to match BDP then we
--	 * estimate queue is drained; persisting would underutilize the pipe.
--	 */
--	return is_full_length ||
--		inflight <= bbr_inflight(sk, bw, BBR_UNIT);
--}
--
--static void bbr_advance_cycle_phase(struct sock *sk)
--{
--	struct tcp_sock *tp = tcp_sk(sk);
--	struct bbr *bbr = inet_csk_ca(sk);
--
--	bbr->cycle_idx = (bbr->cycle_idx + 1) & (CYCLE_LEN - 1);
--	bbr->cycle_mstamp = tp->delivered_mstamp;
--}
--
--/* Gain cycling: cycle pacing gain to converge to fair share of available bw. */
--static void bbr_update_cycle_phase(struct sock *sk,
--				   const struct rate_sample *rs)
--{
--	struct bbr *bbr = inet_csk_ca(sk);
--
--	if (bbr->mode == BBR_PROBE_BW && bbr_is_next_cycle_phase(sk, rs))
--		bbr_advance_cycle_phase(sk);
-+		tcp_snd_cwnd_set(tp, min_t(u32, tcp_snd_cwnd(tp),
-+					   bbr_probe_rtt_cwnd(sk)));
- }
- 
- static void bbr_reset_startup_mode(struct sock *sk)
-@@ -613,191 +739,49 @@ static void bbr_reset_startup_mode(struct sock *sk)
- 	bbr->mode = BBR_STARTUP;
- }
- 
--static void bbr_reset_probe_bw_mode(struct sock *sk)
--{
--	struct bbr *bbr = inet_csk_ca(sk);
--
--	bbr->mode = BBR_PROBE_BW;
--	bbr->cycle_idx = CYCLE_LEN - 1 - prandom_u32_max(bbr_cycle_rand);
--	bbr_advance_cycle_phase(sk);	/* flip to next phase of gain cycle */
--}
--
--static void bbr_reset_mode(struct sock *sk)
--{
--	if (!bbr_full_bw_reached(sk))
--		bbr_reset_startup_mode(sk);
--	else
--		bbr_reset_probe_bw_mode(sk);
--}
--
--/* Start a new long-term sampling interval. */
--static void bbr_reset_lt_bw_sampling_interval(struct sock *sk)
--{
--	struct tcp_sock *tp = tcp_sk(sk);
--	struct bbr *bbr = inet_csk_ca(sk);
--
--	bbr->lt_last_stamp = div_u64(tp->delivered_mstamp, USEC_PER_MSEC);
--	bbr->lt_last_delivered = tp->delivered;
--	bbr->lt_last_lost = tp->lost;
--	bbr->lt_rtt_cnt = 0;
--}
--
--/* Completely reset long-term bandwidth sampling. */
--static void bbr_reset_lt_bw_sampling(struct sock *sk)
--{
--	struct bbr *bbr = inet_csk_ca(sk);
--
--	bbr->lt_bw = 0;
--	bbr->lt_use_bw = 0;
--	bbr->lt_is_sampling = false;
--	bbr_reset_lt_bw_sampling_interval(sk);
--}
--
--/* Long-term bw sampling interval is done. Estimate whether we're policed. */
--static void bbr_lt_bw_interval_done(struct sock *sk, u32 bw)
--{
--	struct bbr *bbr = inet_csk_ca(sk);
--	u32 diff;
--
--	if (bbr->lt_bw) {  /* do we have bw from a previous interval? */
--		/* Is new bw close to the lt_bw from the previous interval? */
--		diff = abs(bw - bbr->lt_bw);
--		if ((diff * BBR_UNIT <= bbr_lt_bw_ratio * bbr->lt_bw) ||
--		    (bbr_rate_bytes_per_sec(sk, diff, BBR_UNIT) <=
--		     bbr_lt_bw_diff)) {
--			/* All criteria are met; estimate we're policed. */
--			bbr->lt_bw = (bw + bbr->lt_bw) >> 1;  /* avg 2 intvls */
--			bbr->lt_use_bw = 1;
--			bbr->pacing_gain = BBR_UNIT;  /* try to avoid drops */
--			bbr->lt_rtt_cnt = 0;
--			return;
--		}
--	}
--	bbr->lt_bw = bw;
--	bbr_reset_lt_bw_sampling_interval(sk);
--}
--
--/* Token-bucket traffic policers are common (see "An Internet-Wide Analysis of
-- * Traffic Policing", SIGCOMM 2016). BBR detects token-bucket policers and
-- * explicitly models their policed rate, to reduce unnecessary losses. We
-- * estimate that we're policed if we see 2 consecutive sampling intervals with
-- * consistent throughput and high packet loss. If we think we're being policed,
-- * set lt_bw to the "long-term" average delivery rate from those 2 intervals.
-+/* See if we have reached next round trip. Upon start of the new round,
-+ * returns packets delivered since previous round start plus this ACK.
-  */
--static void bbr_lt_bw_sampling(struct sock *sk, const struct rate_sample *rs)
--{
--	struct tcp_sock *tp = tcp_sk(sk);
--	struct bbr *bbr = inet_csk_ca(sk);
--	u32 lost, delivered;
--	u64 bw;
--	u32 t;
--
--	if (bbr->lt_use_bw) {	/* already using long-term rate, lt_bw? */
--		if (bbr->mode == BBR_PROBE_BW && bbr->round_start &&
--		    ++bbr->lt_rtt_cnt >= bbr_lt_bw_max_rtts) {
--			bbr_reset_lt_bw_sampling(sk);    /* stop using lt_bw */
--			bbr_reset_probe_bw_mode(sk);  /* restart gain cycling */
--		}
--		return;
--	}
--
--	/* Wait for the first loss before sampling, to let the policer exhaust
--	 * its tokens and estimate the steady-state rate allowed by the policer.
--	 * Starting samples earlier includes bursts that over-estimate the bw.
--	 */
--	if (!bbr->lt_is_sampling) {
--		if (!rs->losses)
--			return;
--		bbr_reset_lt_bw_sampling_interval(sk);
--		bbr->lt_is_sampling = true;
--	}
--
--	/* To avoid underestimates, reset sampling if we run out of data. */
--	if (rs->is_app_limited) {
--		bbr_reset_lt_bw_sampling(sk);
--		return;
--	}
--
--	if (bbr->round_start)
--		bbr->lt_rtt_cnt++;	/* count round trips in this interval */
--	if (bbr->lt_rtt_cnt < bbr_lt_intvl_min_rtts)
--		return;		/* sampling interval needs to be longer */
--	if (bbr->lt_rtt_cnt > 4 * bbr_lt_intvl_min_rtts) {
--		bbr_reset_lt_bw_sampling(sk);  /* interval is too long */
--		return;
--	}
--
--	/* End sampling interval when a packet is lost, so we estimate the
--	 * policer tokens were exhausted. Stopping the sampling before the
--	 * tokens are exhausted under-estimates the policed rate.
--	 */
--	if (!rs->losses)
--		return;
--
--	/* Calculate packets lost and delivered in sampling interval. */
--	lost = tp->lost - bbr->lt_last_lost;
--	delivered = tp->delivered - bbr->lt_last_delivered;
--	/* Is loss rate (lost/delivered) >= lt_loss_thresh? If not, wait. */
--	if (!delivered || (lost << BBR_SCALE) < bbr_lt_loss_thresh * delivered)
--		return;
--
--	/* Find average delivery rate in this sampling interval. */
--	t = div_u64(tp->delivered_mstamp, USEC_PER_MSEC) - bbr->lt_last_stamp;
--	if ((s32)t < 1)
--		return;		/* interval is less than one ms, so wait */
--	/* Check if can multiply without overflow */
--	if (t >= ~0U / USEC_PER_MSEC) {
--		bbr_reset_lt_bw_sampling(sk);  /* interval too long; reset */
--		return;
--	}
--	t *= USEC_PER_MSEC;
--	bw = (u64)delivered * BW_UNIT;
--	do_div(bw, t);
--	bbr_lt_bw_interval_done(sk, bw);
--}
--
--/* Estimate the bandwidth based on how fast packets are delivered */
--static void bbr_update_bw(struct sock *sk, const struct rate_sample *rs)
-+static u32 bbr_update_round_start(struct sock *sk,
-+		const struct rate_sample *rs, struct bbr_context *ctx)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
- 	struct bbr *bbr = inet_csk_ca(sk);
--	u64 bw;
-+	u32 round_delivered = 0;
- 
- 	bbr->round_start = 0;
--	if (rs->delivered < 0 || rs->interval_us <= 0)
--		return; /* Not a valid observation */
- 
- 	/* See if we've reached the next RTT */
--	if (!before(rs->prior_delivered, bbr->next_rtt_delivered)) {
-+	if (rs->interval_us > 0 &&
-+	    !before(rs->prior_delivered, bbr->next_rtt_delivered)) {
-+		round_delivered = tp->delivered - bbr->next_rtt_delivered;
- 		bbr->next_rtt_delivered = tp->delivered;
--		bbr->rtt_cnt++;
- 		bbr->round_start = 1;
--		bbr->packet_conservation = 0;
- 	}
-+	return round_delivered;
-+}
- 
--	bbr_lt_bw_sampling(sk, rs);
-+/* Calculate the bandwidth based on how fast packets are delivered */
-+static void bbr_calculate_bw_sample(struct sock *sk,
-+			const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	u64 bw = 0;
- 
- 	/* Divide delivered by the interval to find a (lower bound) bottleneck
- 	 * bandwidth sample. Delivered is in packets and interval_us in uS and
- 	 * ratio will be <<1 for most connections. So delivered is first scaled.
-+	 * Round up to allow growth at low rates, even with integer division.
- 	 */
--	bw = div64_long((u64)rs->delivered * BW_UNIT, rs->interval_us);
--
--	/* If this sample is application-limited, it is likely to have a very
--	 * low delivered count that represents application behavior rather than
--	 * the available network rate. Such a sample could drag down estimated
--	 * bw, causing needless slow-down. Thus, to continue to send at the
--	 * last measured network rate, we filter out app-limited samples unless
--	 * they describe the path bw at least as well as our bw model.
--	 *
--	 * So the goal during app-limited phase is to proceed with the best
--	 * network rate no matter how long. We automatically leave this
--	 * phase when app writes faster than the network can deliver :)
--	 */
--	if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) {
--		/* Incorporate new sample into our max bw filter. */
--		minmax_running_max(&bbr->bw, bbr_bw_rtts, bbr->rtt_cnt, bw);
-+	if (rs->interval_us > 0) {
-+		if (WARN_ONCE(rs->delivered < 0,
-+			      "negative delivered: %d interval_us: %ld\n",
-+			      rs->delivered, rs->interval_us))
-+			return;
-+
-+		bw = DIV_ROUND_UP_ULL((u64)rs->delivered * BW_UNIT, rs->interval_us);
- 	}
-+
-+	ctx->sample_bw = bw;
- }
- 
- /* Estimates the windowed max degree of ack aggregation.
-@@ -811,7 +795,7 @@ static void bbr_update_bw(struct sock *sk, const struct rate_sample *rs)
-  *
-  * Max extra_acked is clamped by cwnd and bw * bbr_extra_acked_max_us (100 ms).
-  * Max filter is an approximate sliding window of 5-10 (packet timed) round
-- * trips.
-+ * trips for non-startup phase, and 1-2 round trips for startup.
-  */
- static void bbr_update_ack_aggregation(struct sock *sk,
- 				       const struct rate_sample *rs)
-@@ -819,15 +803,19 @@ static void bbr_update_ack_aggregation(struct sock *sk,
- 	u32 epoch_us, expected_acked, extra_acked;
- 	struct bbr *bbr = inet_csk_ca(sk);
- 	struct tcp_sock *tp = tcp_sk(sk);
-+	u32 extra_acked_win_rtts_thresh = bbr_param(sk, extra_acked_win_rtts);
- 
--	if (!bbr_extra_acked_gain || rs->acked_sacked <= 0 ||
-+	if (!bbr_param(sk, extra_acked_gain) || rs->acked_sacked <= 0 ||
- 	    rs->delivered < 0 || rs->interval_us <= 0)
- 		return;
- 
- 	if (bbr->round_start) {
- 		bbr->extra_acked_win_rtts = min(0x1F,
- 						bbr->extra_acked_win_rtts + 1);
--		if (bbr->extra_acked_win_rtts >= bbr_extra_acked_win_rtts) {
-+		if (!bbr_full_bw_reached(sk))
-+			extra_acked_win_rtts_thresh = 1;
-+		if (bbr->extra_acked_win_rtts >=
-+		    extra_acked_win_rtts_thresh) {
- 			bbr->extra_acked_win_rtts = 0;
- 			bbr->extra_acked_win_idx = bbr->extra_acked_win_idx ?
- 						   0 : 1;
-@@ -861,49 +849,6 @@ static void bbr_update_ack_aggregation(struct sock *sk,
- 		bbr->extra_acked[bbr->extra_acked_win_idx] = extra_acked;
- }
- 
--/* Estimate when the pipe is full, using the change in delivery rate: BBR
-- * estimates that STARTUP filled the pipe if the estimated bw hasn't changed by
-- * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited
-- * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the
-- * higher rwin, 3: we get higher delivery rate samples. Or transient
-- * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar
-- * design goal, but uses delay and inter-ACK spacing instead of bandwidth.
-- */
--static void bbr_check_full_bw_reached(struct sock *sk,
--				      const struct rate_sample *rs)
--{
--	struct bbr *bbr = inet_csk_ca(sk);
--	u32 bw_thresh;
--
--	if (bbr_full_bw_reached(sk) || !bbr->round_start || rs->is_app_limited)
--		return;
--
--	bw_thresh = (u64)bbr->full_bw * bbr_full_bw_thresh >> BBR_SCALE;
--	if (bbr_max_bw(sk) >= bw_thresh) {
--		bbr->full_bw = bbr_max_bw(sk);
--		bbr->full_bw_cnt = 0;
--		return;
--	}
--	++bbr->full_bw_cnt;
--	bbr->full_bw_reached = bbr->full_bw_cnt >= bbr_full_bw_cnt;
--}
--
--/* If pipe is probably full, drain the queue and then enter steady-state. */
--static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs)
--{
--	struct bbr *bbr = inet_csk_ca(sk);
--
--	if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) {
--		bbr->mode = BBR_DRAIN;	/* drain queue we created */
--		tcp_sk(sk)->snd_ssthresh =
--				bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
--	}	/* fall through to check if in-flight is already small: */
--	if (bbr->mode == BBR_DRAIN &&
--	    bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <=
--	    bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT))
--		bbr_reset_probe_bw_mode(sk);  /* we estimate queue is drained */
--}
--
- static void bbr_check_probe_rtt_done(struct sock *sk)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
-@@ -913,9 +858,9 @@ static void bbr_check_probe_rtt_done(struct sock *sk)
- 	      after(tcp_jiffies32, bbr->probe_rtt_done_stamp)))
- 		return;
- 
--	bbr->min_rtt_stamp = tcp_jiffies32;  /* wait a while until PROBE_RTT */
-+	bbr->probe_rtt_min_stamp = tcp_jiffies32; /* schedule next PROBE_RTT */
- 	tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd));
--	bbr_reset_mode(sk);
-+	bbr_exit_probe_rtt(sk);
- }
- 
- /* The goal of PROBE_RTT mode is to have BBR flows cooperatively and
-@@ -941,23 +886,35 @@ static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
- 	struct bbr *bbr = inet_csk_ca(sk);
--	bool filter_expired;
-+	bool probe_rtt_expired, min_rtt_expired;
-+	u32 expire;
- 
--	/* Track min RTT seen in the min_rtt_win_sec filter window: */
--	filter_expired = after(tcp_jiffies32,
--			       bbr->min_rtt_stamp + bbr_min_rtt_win_sec * HZ);
-+	/* Track min RTT in probe_rtt_win_ms to time next PROBE_RTT state. */
-+	expire = bbr->probe_rtt_min_stamp +
-+		 msecs_to_jiffies(bbr_param(sk, probe_rtt_win_ms));
-+	probe_rtt_expired = after(tcp_jiffies32, expire);
- 	if (rs->rtt_us >= 0 &&
--	    (rs->rtt_us < bbr->min_rtt_us ||
--	     (filter_expired && !rs->is_ack_delayed))) {
--		bbr->min_rtt_us = rs->rtt_us;
--		bbr->min_rtt_stamp = tcp_jiffies32;
-+	    (rs->rtt_us < bbr->probe_rtt_min_us ||
-+	     (probe_rtt_expired && !rs->is_ack_delayed))) {
-+		bbr->probe_rtt_min_us = rs->rtt_us;
-+		bbr->probe_rtt_min_stamp = tcp_jiffies32;
-+	}
-+	/* Track min RTT seen in the min_rtt_win_sec filter window: */
-+	expire = bbr->min_rtt_stamp + bbr_param(sk, min_rtt_win_sec) * HZ;
-+	min_rtt_expired = after(tcp_jiffies32, expire);
-+	if (bbr->probe_rtt_min_us <= bbr->min_rtt_us ||
-+	    min_rtt_expired) {
-+		bbr->min_rtt_us = bbr->probe_rtt_min_us;
-+		bbr->min_rtt_stamp = bbr->probe_rtt_min_stamp;
- 	}
- 
--	if (bbr_probe_rtt_mode_ms > 0 && filter_expired &&
-+	if (bbr_param(sk, probe_rtt_mode_ms) > 0 && probe_rtt_expired &&
- 	    !bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) {
- 		bbr->mode = BBR_PROBE_RTT;  /* dip, drain queue */
- 		bbr_save_cwnd(sk);  /* note cwnd so we can restore it */
- 		bbr->probe_rtt_done_stamp = 0;
-+		bbr->ack_phase = BBR_ACKS_PROBE_STOPPING;
-+		bbr->next_rtt_delivered = tp->delivered;
- 	}
- 
- 	if (bbr->mode == BBR_PROBE_RTT) {
-@@ -966,9 +923,9 @@ static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs)
- 			(tp->delivered + tcp_packets_in_flight(tp)) ? : 1;
- 		/* Maintain min packets in flight for max(200 ms, 1 round). */
- 		if (!bbr->probe_rtt_done_stamp &&
--		    tcp_packets_in_flight(tp) <= bbr_cwnd_min_target) {
-+		    tcp_packets_in_flight(tp) <= bbr_probe_rtt_cwnd(sk)) {
- 			bbr->probe_rtt_done_stamp = tcp_jiffies32 +
--				msecs_to_jiffies(bbr_probe_rtt_mode_ms);
-+				msecs_to_jiffies(bbr_param(sk, probe_rtt_mode_ms));
- 			bbr->probe_rtt_round_done = 0;
- 			bbr->next_rtt_delivered = tp->delivered;
- 		} else if (bbr->probe_rtt_done_stamp) {
-@@ -989,18 +946,20 @@ static void bbr_update_gains(struct sock *sk)
- 
- 	switch (bbr->mode) {
- 	case BBR_STARTUP:
--		bbr->pacing_gain = bbr_high_gain;
--		bbr->cwnd_gain	 = bbr_high_gain;
-+		bbr->pacing_gain = bbr_param(sk, startup_pacing_gain);
-+		bbr->cwnd_gain	 = bbr_param(sk, startup_cwnd_gain);
- 		break;
- 	case BBR_DRAIN:
--		bbr->pacing_gain = bbr_drain_gain;	/* slow, to drain */
--		bbr->cwnd_gain	 = bbr_high_gain;	/* keep cwnd */
-+		bbr->pacing_gain = bbr_param(sk, drain_gain);  /* slow, to drain */
-+		bbr->cwnd_gain	 = bbr_param(sk, startup_cwnd_gain);  /* keep cwnd */
- 		break;
- 	case BBR_PROBE_BW:
--		bbr->pacing_gain = (bbr->lt_use_bw ?
--				    BBR_UNIT :
--				    bbr_pacing_gain[bbr->cycle_idx]);
--		bbr->cwnd_gain	 = bbr_cwnd_gain;
-+		bbr->pacing_gain = bbr_pacing_gain[bbr->cycle_idx];
-+		bbr->cwnd_gain	 = bbr_param(sk, cwnd_gain);
-+		if (bbr_param(sk, bw_probe_cwnd_gain) &&
-+		    bbr->cycle_idx == BBR_BW_PROBE_UP)
-+			bbr->cwnd_gain +=
-+				BBR_UNIT * bbr_param(sk, bw_probe_cwnd_gain) / 4;
- 		break;
- 	case BBR_PROBE_RTT:
- 		bbr->pacing_gain = BBR_UNIT;
-@@ -1012,167 +971,1409 @@ static void bbr_update_gains(struct sock *sk)
- 	}
- }
- 
--static void bbr_update_model(struct sock *sk, const struct rate_sample *rs)
-+static u32 bbr_sndbuf_expand(struct sock *sk)
- {
--	bbr_update_bw(sk, rs);
--	bbr_update_ack_aggregation(sk, rs);
--	bbr_update_cycle_phase(sk, rs);
--	bbr_check_full_bw_reached(sk, rs);
--	bbr_check_drain(sk, rs);
--	bbr_update_min_rtt(sk, rs);
--	bbr_update_gains(sk);
-+	/* Provision 3 * cwnd since BBR may slow-start even during recovery. */
-+	return 3;
- }
- 
--static void bbr_main(struct sock *sk, const struct rate_sample *rs)
-+/* Incorporate a new bw sample into the current window of our max filter. */
-+static void bbr_take_max_bw_sample(struct sock *sk, u32 bw)
- {
- 	struct bbr *bbr = inet_csk_ca(sk);
--	u32 bw;
- 
--	bbr_update_model(sk, rs);
--
--	bw = bbr_bw(sk);
--	bbr_set_pacing_rate(sk, bw, bbr->pacing_gain);
--	bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain);
-+	bbr->bw_hi[1] = max(bw, bbr->bw_hi[1]);
- }
- 
--static void bbr_init(struct sock *sk)
-+/* Keep max of last 1-2 cycles. Each PROBE_BW cycle, flip filter window. */
-+static void bbr_advance_max_bw_filter(struct sock *sk)
- {
--	struct tcp_sock *tp = tcp_sk(sk);
- 	struct bbr *bbr = inet_csk_ca(sk);
- 
--	bbr->prior_cwnd = 0;
--	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
--	bbr->rtt_cnt = 0;
--	bbr->next_rtt_delivered = tp->delivered;
--	bbr->prev_ca_state = TCP_CA_Open;
--	bbr->packet_conservation = 0;
--
--	bbr->probe_rtt_done_stamp = 0;
--	bbr->probe_rtt_round_done = 0;
--	bbr->min_rtt_us = tcp_min_rtt(tp);
--	bbr->min_rtt_stamp = tcp_jiffies32;
--
--	minmax_reset(&bbr->bw, bbr->rtt_cnt, 0);  /* init max bw to 0 */
-+	if (!bbr->bw_hi[1])
-+		return;  /* no samples in this window; remember old window */
-+	bbr->bw_hi[0] = bbr->bw_hi[1];
-+	bbr->bw_hi[1] = 0;
-+}
- 
--	bbr->has_seen_rtt = 0;
--	bbr_init_pacing_rate_from_rtt(sk);
-+/* Reset the estimator for reaching full bandwidth based on bw plateau. */
-+static void bbr_reset_full_bw(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
- 
--	bbr->round_start = 0;
--	bbr->idle_restart = 0;
--	bbr->full_bw_reached = 0;
- 	bbr->full_bw = 0;
- 	bbr->full_bw_cnt = 0;
--	bbr->cycle_mstamp = 0;
--	bbr->cycle_idx = 0;
--	bbr_reset_lt_bw_sampling(sk);
--	bbr_reset_startup_mode(sk);
-+	bbr->full_bw_now = 0;
-+}
- 
--	bbr->ack_epoch_mstamp = tp->tcp_mstamp;
--	bbr->ack_epoch_acked = 0;
--	bbr->extra_acked_win_rtts = 0;
--	bbr->extra_acked_win_idx = 0;
--	bbr->extra_acked[0] = 0;
--	bbr->extra_acked[1] = 0;
-+/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */
-+static u32 bbr_target_inflight(struct sock *sk)
-+{
-+	u32 bdp = bbr_inflight(sk, bbr_bw(sk), BBR_UNIT);
- 
--	cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED);
-+	return min(bdp, tcp_sk(sk)->snd_cwnd);
- }
- 
--static u32 bbr_sndbuf_expand(struct sock *sk)
-+static bool bbr_is_probing_bandwidth(struct sock *sk)
- {
--	/* Provision 3 * cwnd since BBR may slow-start even during recovery. */
--	return 3;
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return (bbr->mode == BBR_STARTUP) ||
-+		(bbr->mode == BBR_PROBE_BW &&
-+		 (bbr->cycle_idx == BBR_BW_PROBE_REFILL ||
-+		  bbr->cycle_idx == BBR_BW_PROBE_UP));
-+}
-+
-+/* Has the given amount of time elapsed since we marked the phase start? */
-+static bool bbr_has_elapsed_in_phase(const struct sock *sk, u32 interval_us)
-+{
-+	const struct tcp_sock *tp = tcp_sk(sk);
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return tcp_stamp_us_delta(tp->tcp_mstamp,
-+				  bbr->cycle_mstamp + interval_us) > 0;
-+}
-+
-+static void bbr_handle_queue_too_high_in_startup(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bdp;  /* estimated BDP in packets, with quantization budget */
-+
-+	bbr->full_bw_reached = 1;
-+
-+	bdp = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+	bbr->inflight_hi = max(bdp, bbr->inflight_latest);
-+}
-+
-+/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */
-+static void bbr_check_ecn_too_high_in_startup(struct sock *sk, u32 ce_ratio)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr_full_bw_reached(sk) || !bbr->ecn_eligible ||
-+	    !bbr_param(sk, full_ecn_cnt) || !bbr_param(sk, ecn_thresh))
-+		return;
-+
-+	if (ce_ratio >= bbr_param(sk, ecn_thresh))
-+		bbr->startup_ecn_rounds++;
-+	else
-+		bbr->startup_ecn_rounds = 0;
-+
-+	if (bbr->startup_ecn_rounds >= bbr_param(sk, full_ecn_cnt)) {
-+		bbr_handle_queue_too_high_in_startup(sk);
-+		return;
-+	}
-+}
-+
-+/* Updates ecn_alpha and returns ce_ratio. -1 if not available. */
-+static int bbr_update_ecn_alpha(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct net *net = sock_net(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	s32 delivered, delivered_ce;
-+	u64 alpha, ce_ratio;
-+	u32 gain;
-+	bool want_ecn_alpha;
-+
-+	/* See if we should use ECN sender logic for this connection. */
-+	if (!bbr->ecn_eligible && bbr_can_use_ecn(sk) &&
-+	    !!bbr_param(sk, ecn_factor) &&
-+	    (bbr->min_rtt_us <= bbr_ecn_max_rtt_us ||
-+	     !bbr_ecn_max_rtt_us))
-+		bbr->ecn_eligible = 1;
-+
-+	/* Skip updating alpha only if not ECN-eligible and PLB is disabled. */
-+	want_ecn_alpha = (bbr->ecn_eligible ||
-+			  (bbr_can_use_ecn(sk) &&
-+			   READ_ONCE(net->ipv4.sysctl_tcp_plb_enabled)));
-+	if (!want_ecn_alpha)
-+		return -1;
-+
-+	delivered = tp->delivered - bbr->alpha_last_delivered;
-+	delivered_ce = tp->delivered_ce - bbr->alpha_last_delivered_ce;
-+
-+	if (delivered == 0 ||		/* avoid divide by zero */
-+	    WARN_ON_ONCE(delivered < 0 || delivered_ce < 0))  /* backwards? */
-+		return -1;
-+
-+	BUILD_BUG_ON(BBR_SCALE != TCP_PLB_SCALE);
-+	ce_ratio = (u64)delivered_ce << BBR_SCALE;
-+	do_div(ce_ratio, delivered);
-+
-+	gain = bbr_param(sk, ecn_alpha_gain);
-+	alpha = ((BBR_UNIT - gain) * bbr->ecn_alpha) >> BBR_SCALE;
-+	alpha += (gain * ce_ratio) >> BBR_SCALE;
-+	bbr->ecn_alpha = min_t(u32, alpha, BBR_UNIT);
-+
-+	bbr->alpha_last_delivered = tp->delivered;
-+	bbr->alpha_last_delivered_ce = tp->delivered_ce;
-+
-+	bbr_check_ecn_too_high_in_startup(sk, ce_ratio);
-+	return (int)ce_ratio;
- }
- 
--/* In theory BBR does not need to undo the cwnd since it does not
-- * always reduce cwnd on losses (see bbr_main()). Keep it for now.
-+/* Protective Load Balancing (PLB). PLB rehashes outgoing data (to a new IPv6
-+ * flow label) if it encounters sustained congestion in the form of ECN marks.
-  */
--static u32 bbr_undo_cwnd(struct sock *sk)
-+static void bbr_plb(struct sock *sk, const struct rate_sample *rs, int ce_ratio)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->round_start && ce_ratio >= 0)
-+		tcp_plb_update_state(sk, &bbr->plb, ce_ratio);
-+
-+	tcp_plb_check_rehash(sk, &bbr->plb);
-+}
-+
-+/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */
-+static void bbr_raise_inflight_hi_slope(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 growth_this_round, cnt;
-+
-+	/* Calculate "slope": packets S/Acked per inflight_hi increment. */
-+	growth_this_round = 1 << bbr->bw_probe_up_rounds;
-+	bbr->bw_probe_up_rounds = min(bbr->bw_probe_up_rounds + 1, 30);
-+	cnt = tcp_snd_cwnd(tp) / growth_this_round;
-+	cnt = max(cnt, 1U);
-+	bbr->bw_probe_up_cnt = cnt;
-+}
-+
-+/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */
-+static void bbr_probe_inflight_hi_upward(struct sock *sk,
-+					  const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 delta;
-+
-+	if (!tp->is_cwnd_limited || tcp_snd_cwnd(tp) < bbr->inflight_hi)
-+		return;  /* not fully using inflight_hi, so don't grow it */
-+
-+	/* For each bw_probe_up_cnt packets ACKed, increase inflight_hi by 1. */
-+	bbr->bw_probe_up_acks += rs->acked_sacked;
-+	if (bbr->bw_probe_up_acks >=  bbr->bw_probe_up_cnt) {
-+		delta = bbr->bw_probe_up_acks / bbr->bw_probe_up_cnt;
-+		bbr->bw_probe_up_acks -= delta * bbr->bw_probe_up_cnt;
-+		bbr->inflight_hi += delta;
-+		bbr->try_fast_path = 0;  /* Need to update cwnd */
-+	}
-+
-+	if (bbr->round_start)
-+		bbr_raise_inflight_hi_slope(sk);
-+}
-+
-+/* Does loss/ECN rate for this sample say inflight is "too high"?
-+ * This is used by both the bbr_check_loss_too_high_in_startup() function,
-+ * and in PROBE_UP.
-+ */
-+static bool bbr_is_inflight_too_high(const struct sock *sk,
-+				      const struct rate_sample *rs)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+	u32 loss_thresh, ecn_thresh;
-+
-+	if (rs->lost > 0 && rs->tx_in_flight) {
-+		loss_thresh = (u64)rs->tx_in_flight * bbr_param(sk, loss_thresh) >>
-+				BBR_SCALE;
-+		if (rs->lost > loss_thresh) {
-+			return true;
-+		}
-+	}
-+
-+	if (rs->delivered_ce > 0 && rs->delivered > 0 &&
-+	    bbr->ecn_eligible && !!bbr_param(sk, ecn_thresh)) {
-+		ecn_thresh = (u64)rs->delivered * bbr_param(sk, ecn_thresh) >>
-+				BBR_SCALE;
-+		if (rs->delivered_ce > ecn_thresh) {
-+			return true;
-+		}
-+	}
-+
-+	return false;
-+}
-+
-+/* Calculate the tx_in_flight level that corresponded to excessive loss.
-+ * We find "lost_prefix" segs of the skb where loss rate went too high,
-+ * by solving for "lost_prefix" in the following equation:
-+ *   lost                     /  inflight                     >= loss_thresh
-+ *  (lost_prev + lost_prefix) / (inflight_prev + lost_prefix) >= loss_thresh
-+ * Then we take that equation, convert it to fixed point, and
-+ * round up to the nearest packet.
-+ */
-+static u32 bbr_inflight_hi_from_lost_skb(const struct sock *sk,
-+					  const struct rate_sample *rs,
-+					  const struct sk_buff *skb)
-+{
-+	const struct tcp_sock *tp = tcp_sk(sk);
-+	u32 loss_thresh  = bbr_param(sk, loss_thresh);
-+	u32 pcount, divisor, inflight_hi;
-+	s32 inflight_prev, lost_prev;
-+	u64 loss_budget, lost_prefix;
-+
-+	pcount = tcp_skb_pcount(skb);
-+
-+	/* How much data was in flight before this skb? */
-+	inflight_prev = rs->tx_in_flight - pcount;
-+	if (inflight_prev < 0) {
-+		WARN_ONCE(tcp_skb_tx_in_flight_is_suspicious(
-+				  pcount,
-+				  TCP_SKB_CB(skb)->sacked,
-+				  rs->tx_in_flight),
-+			  "tx_in_flight: %u pcount: %u reneg: %u",
-+			  rs->tx_in_flight, pcount, tcp_sk(sk)->is_sack_reneg);
-+		return ~0U;
-+	}
-+
-+	/* How much inflight data was marked lost before this skb? */
-+	lost_prev = rs->lost - pcount;
-+	if (WARN_ONCE(lost_prev < 0,
-+		      "cwnd: %u ca: %d out: %u lost: %u pif: %u "
-+		      "tx_in_flight: %u tx.lost: %u tp->lost: %u rs->lost: %d "
-+		      "lost_prev: %d pcount: %d seq: %u end_seq: %u reneg: %u",
-+		      tcp_snd_cwnd(tp), inet_csk(sk)->icsk_ca_state,
-+		      tp->packets_out, tp->lost_out, tcp_packets_in_flight(tp),
-+		      rs->tx_in_flight, TCP_SKB_CB(skb)->tx.lost, tp->lost,
-+		      rs->lost, lost_prev, pcount,
-+		      TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
-+		      tp->is_sack_reneg))
-+		return ~0U;
-+
-+	/* At what prefix of this lost skb did losss rate exceed loss_thresh? */
-+	loss_budget = (u64)inflight_prev * loss_thresh + BBR_UNIT - 1;
-+	loss_budget >>= BBR_SCALE;
-+	if (lost_prev >= loss_budget) {
-+		lost_prefix = 0;   /* previous losses crossed loss_thresh */
-+	} else {
-+		lost_prefix = loss_budget - lost_prev;
-+		lost_prefix <<= BBR_SCALE;
-+		divisor = BBR_UNIT - loss_thresh;
-+		if (WARN_ON_ONCE(!divisor))  /* loss_thresh is 8 bits */
-+			return ~0U;
-+		do_div(lost_prefix, divisor);
-+	}
-+
-+	inflight_hi = inflight_prev + lost_prefix;
-+	return inflight_hi;
-+}
-+
-+/* If loss/ECN rates during probing indicated we may have overfilled a
-+ * buffer, return an operating point that tries to leave unutilized headroom in
-+ * the path for other flows, for fairness convergence and lower RTTs and loss.
-+ */
-+static u32 bbr_inflight_with_headroom(const struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 headroom, headroom_fraction;
-+
-+	if (bbr->inflight_hi == ~0U)
-+		return ~0U;
-+
-+	headroom_fraction = bbr_param(sk, inflight_headroom);
-+	headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE;
-+	headroom = max(headroom, 1U);
-+	return max_t(s32, bbr->inflight_hi - headroom,
-+		     bbr_param(sk, cwnd_min_target));
-+}
-+
-+/* Bound cwnd to a sensible level, based on our current probing state
-+ * machine phase and model of a good inflight level (inflight_lo, inflight_hi).
-+ */
-+static void bbr_bound_cwnd_for_inflight_model(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 cap;
-+
-+	/* tcp_rcv_synsent_state_process() currently calls tcp_ack()
-+	 * and thus cong_control() without first initializing us(!).
-+	 */
-+	if (!bbr->initialized)
-+		return;
-+
-+	cap = ~0U;
-+	if (bbr->mode == BBR_PROBE_BW &&
-+	    bbr->cycle_idx != BBR_BW_PROBE_CRUISE) {
-+		/* Probe to see if more packets fit in the path. */
-+		cap = bbr->inflight_hi;
-+	} else {
-+		if (bbr->mode == BBR_PROBE_RTT ||
-+		    (bbr->mode == BBR_PROBE_BW &&
-+		     bbr->cycle_idx == BBR_BW_PROBE_CRUISE))
-+			cap = bbr_inflight_with_headroom(sk);
-+	}
-+	/* Adapt to any loss/ECN since our last bw probe. */
-+	cap = min(cap, bbr->inflight_lo);
-+
-+	cap = max_t(u32, cap, bbr_param(sk, cwnd_min_target));
-+	tcp_snd_cwnd_set(tp, min(cap, tcp_snd_cwnd(tp)));
-+}
-+
-+/* How should we multiplicatively cut bw or inflight limits based on ECN? */
-+static u32 bbr_ecn_cut(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return BBR_UNIT -
-+		((bbr->ecn_alpha * bbr_param(sk, ecn_factor)) >> BBR_SCALE);
-+}
-+
-+/* Init lower bounds if have not inited yet. */
-+static void bbr_init_lower_bounds(struct sock *sk, bool init_bw)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (init_bw && bbr->bw_lo == ~0U)
-+		bbr->bw_lo = bbr_max_bw(sk);
-+	if (bbr->inflight_lo == ~0U)
-+		bbr->inflight_lo = tcp_snd_cwnd(tp);
-+}
-+
-+/* Reduce bw and inflight to (1 - beta). */
-+static void bbr_loss_lower_bounds(struct sock *sk, u32 *bw, u32 *inflight)
-+{
-+	struct bbr* bbr = inet_csk_ca(sk);
-+	u32 loss_cut = BBR_UNIT - bbr_param(sk, beta);
-+
-+	*bw = max_t(u32, bbr->bw_latest,
-+		    (u64)bbr->bw_lo * loss_cut >> BBR_SCALE);
-+	*inflight = max_t(u32, bbr->inflight_latest,
-+			  (u64)bbr->inflight_lo * loss_cut >> BBR_SCALE);
-+}
-+
-+/* Reduce inflight to (1 - alpha*ecn_factor). */
-+static void bbr_ecn_lower_bounds(struct sock *sk, u32 *inflight)
- {
- 	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 ecn_cut = bbr_ecn_cut(sk);
-+
-+	*inflight = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE;
-+}
-+
-+/* Estimate a short-term lower bound on the capacity available now, based
-+ * on measurements of the current delivery process and recent history. When we
-+ * are seeing loss/ECN at times when we are not probing bw, then conservatively
-+ * move toward flow balance by multiplicatively cutting our short-term
-+ * estimated safe rate and volume of data (bw_lo and inflight_lo). We use a
-+ * multiplicative decrease in order to converge to a lower capacity in time
-+ * logarithmic in the magnitude of the decrease.
-+ *
-+ * However, we do not cut our short-term estimates lower than the current rate
-+ * and volume of delivered data from this round trip, since from the current
-+ * delivery process we can estimate the measured capacity available now.
-+ *
-+ * Anything faster than that approach would knowingly risk high loss, which can
-+ * cause low bw for Reno/CUBIC and high loss recovery latency for
-+ * request/response flows using any congestion control.
-+ */
-+static void bbr_adapt_lower_bounds(struct sock *sk,
-+				    const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 ecn_inflight_lo = ~0U;
-+
-+	/* We only use lower-bound estimates when not probing bw.
-+	 * When probing we need to push inflight higher to probe bw.
-+	 */
-+	if (bbr_is_probing_bandwidth(sk))
-+		return;
-+
-+	/* ECN response. */
-+	if (bbr->ecn_in_round && !!bbr_param(sk, ecn_factor)) {
-+		bbr_init_lower_bounds(sk, false);
-+		bbr_ecn_lower_bounds(sk, &ecn_inflight_lo);
-+	}
-+
-+	/* Loss response. */
-+	if (bbr->loss_in_round) {
-+		bbr_init_lower_bounds(sk, true);
-+		bbr_loss_lower_bounds(sk, &bbr->bw_lo, &bbr->inflight_lo);
-+	}
-+
-+	/* Adjust to the lower of the levels implied by loss/ECN. */
-+	bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo);
-+	bbr->bw_lo = max(1U, bbr->bw_lo);
-+}
-+
-+/* Reset any short-term lower-bound adaptation to congestion, so that we can
-+ * push our inflight up.
-+ */
-+static void bbr_reset_lower_bounds(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->bw_lo = ~0U;
-+	bbr->inflight_lo = ~0U;
-+}
-+
-+/* After bw probing (STARTUP/PROBE_UP), reset signals before entering a state
-+ * machine phase where we adapt our lower bound based on congestion signals.
-+ */
-+static void bbr_reset_congestion_signals(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->loss_in_round = 0;
-+	bbr->ecn_in_round = 0;
-+	bbr->loss_in_cycle = 0;
-+	bbr->ecn_in_cycle = 0;
-+	bbr->bw_latest = 0;
-+	bbr->inflight_latest = 0;
-+}
-+
-+static void bbr_exit_loss_recovery(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd));
-+	bbr->try_fast_path = 0; /* bound cwnd using latest model */
-+}
-+
-+/* Update rate and volume of delivered data from latest round trip. */
-+static void bbr_update_latest_delivery_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->loss_round_start = 0;
-+	if (rs->interval_us <= 0 || !rs->acked_sacked)
-+		return; /* Not a valid observation */
-+
-+	bbr->bw_latest       = max_t(u32, bbr->bw_latest,       ctx->sample_bw);
-+	bbr->inflight_latest = max_t(u32, bbr->inflight_latest, rs->delivered);
-+
-+	if (!before(rs->prior_delivered, bbr->loss_round_delivered)) {
-+		bbr->loss_round_delivered = tp->delivered;
-+		bbr->loss_round_start = 1;  /* mark start of new round trip */
-+	}
-+}
-+
-+/* Once per round, reset filter for latest rate and volume of delivered data. */
-+static void bbr_advance_latest_delivery_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* If ACK matches a TLP retransmit, persist the filter. If we detect
-+	 * that a TLP retransmit plugged a tail loss, we'll want to remember
-+	 * how much data the path delivered before the tail loss.
-+	 */
-+	if (bbr->loss_round_start && !rs->is_acking_tlp_retrans_seq) {
-+		bbr->bw_latest = ctx->sample_bw;
-+		bbr->inflight_latest = rs->delivered;
-+	}
-+}
-+
-+/* Update (most of) our congestion signals: track the recent rate and volume of
-+ * delivered data, presence of loss, and EWMA degree of ECN marking.
-+ */
-+static void bbr_update_congestion_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u64 bw;
-+
-+	if (rs->interval_us <= 0 || !rs->acked_sacked)
-+		return; /* Not a valid observation */
-+	bw = ctx->sample_bw;
-+
-+	if (!rs->is_app_limited || bw >= bbr_max_bw(sk))
-+		bbr_take_max_bw_sample(sk, bw);
-+
-+	bbr->loss_in_round |= (rs->losses > 0);
-+
-+	if (!bbr->loss_round_start)
-+		return;		/* skip the per-round-trip updates */
-+	/* Now do per-round-trip updates. */
-+	bbr_adapt_lower_bounds(sk, rs);
-+
-+	bbr->loss_in_round = 0;
-+	bbr->ecn_in_round  = 0;
-+}
-+
-+/* Bandwidth probing can cause loss. To help coexistence with loss-based
-+ * congestion control we spread out our probing in a Reno-conscious way. Due to
-+ * the shape of the Reno sawtooth, the time required between loss epochs for an
-+ * idealized Reno flow is a number of round trips that is the BDP of that
-+ * flow. We count packet-timed round trips directly, since measured RTT can
-+ * vary widely, and Reno is driven by packet-timed round trips.
-+ */
-+static bool bbr_is_reno_coexistence_probe_time(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 rounds;
-+
-+	/* Random loss can shave some small percentage off of our inflight
-+	 * in each round. To survive this, flows need robust periodic probes.
-+	 */
-+	rounds = min_t(u32, bbr_param(sk, bw_probe_max_rounds), bbr_target_inflight(sk));
-+	return bbr->rounds_since_probe >= rounds;
-+}
-+
-+/* How long do we want to wait before probing for bandwidth (and risking
-+ * loss)? We randomize the wait, for better mixing and fairness convergence.
-+ *
-+ * We bound the Reno-coexistence inter-bw-probe time to be 62-63 round trips.
-+ * This is calculated to allow fairness with a 25Mbps, 30ms Reno flow,
-+ * (eg 4K video to a broadband user):
-+ *   BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets
-+ *
-+ * We bound the BBR-native inter-bw-probe wall clock time to be:
-+ *  (a) higher than 2 sec: to try to avoid causing loss for a long enough time
-+ *      to allow Reno at 30ms to get 4K video bw, the inter-bw-probe time must
-+ *      be at least: 25Mbps * .030sec / (1514bytes) * 0.030sec = 1.9secs
-+ *  (b) lower than 3 sec: to ensure flows can start probing in a reasonable
-+ *      amount of time to discover unutilized bw on human-scale interactive
-+ *      time-scales (e.g. perhaps traffic from a web page download that we
-+ *      were competing with is now complete).
-+ */
-+static void bbr_pick_probe_wait(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Decide the random round-trip bound for wait until probe: */
-+	bbr->rounds_since_probe =
-+		get_random_u32_below(bbr_param(sk, bw_probe_rand_rounds));
-+	/* Decide the random wall clock bound for wait until probe: */
-+	bbr->probe_wait_us = bbr_param(sk, bw_probe_base_us) +
-+			     get_random_u32_below(bbr_param(sk, bw_probe_rand_us));
-+}
-+
-+static void bbr_set_cycle_idx(struct sock *sk, int cycle_idx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->cycle_idx = cycle_idx;
-+	/* New phase, so need to update cwnd and pacing rate. */
-+	bbr->try_fast_path = 0;
-+}
-+
-+/* Send at estimated bw to fill the pipe, but not queue. We need this phase
-+ * before PROBE_UP, because as soon as we send faster than the available bw
-+ * we will start building a queue, and if the buffer is shallow we can cause
-+ * loss. If we do not fill the pipe before we cause this loss, our bw_hi and
-+ * inflight_hi estimates will underestimate.
-+ */
-+static void bbr_start_bw_probe_refill(struct sock *sk, u32 bw_probe_up_rounds)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_lower_bounds(sk);
-+	bbr->bw_probe_up_rounds = bw_probe_up_rounds;
-+	bbr->bw_probe_up_acks = 0;
-+	bbr->stopped_risky_probe = 0;
-+	bbr->ack_phase = BBR_ACKS_REFILLING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_REFILL);
-+}
-+
-+/* Now probe max deliverable data rate and volume. */
-+static void bbr_start_bw_probe_up(struct sock *sk, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->ack_phase = BBR_ACKS_PROBE_STARTING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr->cycle_mstamp = tp->tcp_mstamp;
-+	bbr_reset_full_bw(sk);
-+	bbr->full_bw = ctx->sample_bw;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_UP);
-+	bbr_raise_inflight_hi_slope(sk);
-+}
-+
-+/* Start a new PROBE_BW probing cycle of some wall clock length. Pick a wall
-+ * clock time at which to probe beyond an inflight that we think to be
-+ * safe. This will knowingly risk packet loss, so we want to do this rarely, to
-+ * keep packet loss rates low. Also start a round-trip counter, to probe faster
-+ * if we estimate a Reno flow at our BDP would probe faster.
-+ */
-+static void bbr_start_bw_probe_down(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_congestion_signals(sk);
-+	bbr->bw_probe_up_cnt = ~0U;     /* not growing inflight_hi any more */
-+	bbr_pick_probe_wait(sk);
-+	bbr->cycle_mstamp = tp->tcp_mstamp;		/* start wall clock */
-+	bbr->ack_phase = BBR_ACKS_PROBE_STOPPING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_DOWN);
-+}
-+
-+/* Cruise: maintain what we estimate to be a neutral, conservative
-+ * operating point, without attempting to probe up for bandwidth or down for
-+ * RTT, and only reducing inflight in response to loss/ECN signals.
-+ */
-+static void bbr_start_bw_probe_cruise(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->inflight_lo != ~0U)
-+		bbr->inflight_lo = min(bbr->inflight_lo, bbr->inflight_hi);
-+
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_CRUISE);
-+}
-+
-+/* Loss and/or ECN rate is too high while probing.
-+ * Adapt (once per bw probe) by cutting inflight_hi and then restarting cycle.
-+ */
-+static void bbr_handle_inflight_too_high(struct sock *sk,
-+					  const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	const u32 beta = bbr_param(sk, beta);
-+
-+	bbr->prev_probe_too_high = 1;
-+	bbr->bw_probe_samples = 0;  /* only react once per probe */
-+	/* If we are app-limited then we are not robustly
-+	 * probing the max volume of inflight data we think
-+	 * might be safe (analogous to how app-limited bw
-+	 * samples are not known to be robustly probing bw).
-+	 */
-+	if (!rs->is_app_limited) {
-+		bbr->inflight_hi = max_t(u32, rs->tx_in_flight,
-+					 (u64)bbr_target_inflight(sk) *
-+					 (BBR_UNIT - beta) >> BBR_SCALE);
-+	}
-+	if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP)
-+		bbr_start_bw_probe_down(sk);
-+}
-+
-+/* If we're seeing bw and loss samples reflecting our bw probing, adapt
-+ * using the signals we see. If loss or ECN mark rate gets too high, then adapt
-+ * inflight_hi downward. If we're able to push inflight higher without such
-+ * signals, push higher: adapt inflight_hi upward.
-+ */
-+static bool bbr_adapt_upper_bounds(struct sock *sk,
-+				    const struct rate_sample *rs,
-+				    struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Track when we'll see bw/loss samples resulting from our bw probes. */
-+	if (bbr->ack_phase == BBR_ACKS_PROBE_STARTING && bbr->round_start)
-+		bbr->ack_phase = BBR_ACKS_PROBE_FEEDBACK;
-+	if (bbr->ack_phase == BBR_ACKS_PROBE_STOPPING && bbr->round_start) {
-+		/* End of samples from bw probing phase. */
-+		bbr->bw_probe_samples = 0;
-+		bbr->ack_phase = BBR_ACKS_INIT;
-+		/* At this point in the cycle, our current bw sample is also
-+		 * our best recent chance at finding the highest available bw
-+		 * for this flow. So now is the best time to forget the bw
-+		 * samples from the previous cycle, by advancing the window.
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW && !rs->is_app_limited)
-+			bbr_advance_max_bw_filter(sk);
-+		/* If we had an inflight_hi, then probed and pushed inflight all
-+		 * the way up to hit that inflight_hi without seeing any
-+		 * high loss/ECN in all the resulting ACKs from that probing,
-+		 * then probe up again, this time letting inflight persist at
-+		 * inflight_hi for a round trip, then accelerating beyond.
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW &&
-+		    bbr->stopped_risky_probe && !bbr->prev_probe_too_high) {
-+			bbr_start_bw_probe_refill(sk, 0);
-+			return true;  /* yes, decided state transition */
-+		}
-+	}
-+	if (bbr_is_inflight_too_high(sk, rs)) {
-+		if (bbr->bw_probe_samples)  /*  sample is from bw probing? */
-+			bbr_handle_inflight_too_high(sk, rs);
-+	} else {
-+		/* Loss/ECN rate is declared safe. Adjust upper bound upward. */
-+
-+		if (bbr->inflight_hi == ~0U)
-+			return false;   /* no excess queue signals yet */
- 
--	bbr->full_bw = 0;   /* spurious slow-down; reset full pipe detection */
-+		/* To be resilient to random loss, we must raise bw/inflight_hi
-+		 * if we observe in any phase that a higher level is safe.
-+		 */
-+		if (rs->tx_in_flight > bbr->inflight_hi) {
-+			bbr->inflight_hi = rs->tx_in_flight;
-+		}
-+
-+		if (bbr->mode == BBR_PROBE_BW &&
-+		    bbr->cycle_idx == BBR_BW_PROBE_UP)
-+			bbr_probe_inflight_hi_upward(sk, rs);
-+	}
-+
-+	return false;
-+}
-+
-+/* Check if it's time to probe for bandwidth now, and if so, kick it off. */
-+static bool bbr_check_time_to_probe_bw(struct sock *sk,
-+					const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 n;
-+
-+	/* If we seem to be at an operating point where we are not seeing loss
-+	 * but we are seeing ECN marks, then when the ECN marks cease we reprobe
-+	 * quickly (in case cross-traffic has ceased and freed up bw).
-+	 */
-+	if (bbr_param(sk, ecn_reprobe_gain) && bbr->ecn_eligible &&
-+	    bbr->ecn_in_cycle && !bbr->loss_in_cycle &&
-+	    inet_csk(sk)->icsk_ca_state == TCP_CA_Open) {
-+		/* Calculate n so that when bbr_raise_inflight_hi_slope()
-+		 * computes growth_this_round as 2^n it will be roughly the
-+		 * desired volume of data (inflight_hi*ecn_reprobe_gain).
-+		 */
-+		n = ilog2((((u64)bbr->inflight_hi *
-+			    bbr_param(sk, ecn_reprobe_gain)) >> BBR_SCALE));
-+		bbr_start_bw_probe_refill(sk, n);
-+		return true;
-+	}
-+
-+	if (bbr_has_elapsed_in_phase(sk, bbr->probe_wait_us) ||
-+	    bbr_is_reno_coexistence_probe_time(sk)) {
-+		bbr_start_bw_probe_refill(sk, 0);
-+		return true;
-+	}
-+	return false;
-+}
-+
-+/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */
-+static bool bbr_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw)
-+{
-+	/* Always need to pull inflight down to leave headroom in queue. */
-+	if (inflight > bbr_inflight_with_headroom(sk))
-+		return false;
-+
-+	return inflight <= bbr_inflight(sk, bw, BBR_UNIT);
-+}
-+
-+/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */
-+static void bbr_update_cycle_phase(struct sock *sk,
-+				    const struct rate_sample *rs,
-+				    struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	bool is_bw_probe_done = false;
-+	u32 inflight, bw;
-+
-+	if (!bbr_full_bw_reached(sk))
-+		return;
-+
-+	/* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */
-+	if (bbr_adapt_upper_bounds(sk, rs, ctx))
-+		return;		/* already decided state transition */
-+
-+	if (bbr->mode != BBR_PROBE_BW)
-+		return;
-+
-+	inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight);
-+	bw = bbr_max_bw(sk);
-+
-+	switch (bbr->cycle_idx) {
-+	/* First we spend most of our time cruising with a pacing_gain of 1.0,
-+	 * which paces at the estimated bw, to try to fully use the pipe
-+	 * without building queue. If we encounter loss/ECN marks, we adapt
-+	 * by slowing down.
-+	 */
-+	case BBR_BW_PROBE_CRUISE:
-+		if (bbr_check_time_to_probe_bw(sk, rs))
-+			return;		/* already decided state transition */
-+		break;
-+
-+	/* After cruising, when it's time to probe, we first "refill": we send
-+	 * at the estimated bw to fill the pipe, before probing higher and
-+	 * knowingly risking overflowing the bottleneck buffer (causing loss).
-+	 */
-+	case BBR_BW_PROBE_REFILL:
-+		if (bbr->round_start) {
-+			/* After one full round trip of sending in REFILL, we
-+			 * start to see bw samples reflecting our REFILL, which
-+			 * may be putting too much data in flight.
-+			 */
-+			bbr->bw_probe_samples = 1;
-+			bbr_start_bw_probe_up(sk, ctx);
-+		}
-+		break;
-+
-+	/* After we refill the pipe, we probe by using a pacing_gain > 1.0, to
-+	 * probe for bw. If we have not seen loss/ECN, we try to raise inflight
-+	 * to at least pacing_gain*BDP; note that this may take more than
-+	 * min_rtt if min_rtt is small (e.g. on a LAN).
-+	 *
-+	 * We terminate PROBE_UP bandwidth probing upon any of the following:
-+	 *
-+	 * (1) We've pushed inflight up to hit the inflight_hi target set in the
-+	 *     most recent previous bw probe phase. Thus we want to start
-+	 *     draining the queue immediately because it's very likely the most
-+	 *     recently sent packets will fill the queue and cause drops.
-+	 * (2) If inflight_hi has not limited bandwidth growth recently, and
-+	 *     yet delivered bandwidth has not increased much recently
-+	 *     (bbr->full_bw_now).
-+	 * (3) Loss filter says loss rate is "too high".
-+	 * (4) ECN filter says ECN mark rate is "too high".
-+	 *
-+	 * (1) (2) checked here, (3) (4) checked in bbr_is_inflight_too_high()
-+	 */
-+	case BBR_BW_PROBE_UP:
-+		if (bbr->prev_probe_too_high &&
-+		    inflight >= bbr->inflight_hi) {
-+			bbr->stopped_risky_probe = 1;
-+			is_bw_probe_done = true;
-+		} else {
-+			if (tp->is_cwnd_limited &&
-+			    tcp_snd_cwnd(tp) >= bbr->inflight_hi) {
-+				/* inflight_hi is limiting bw growth */
-+				bbr_reset_full_bw(sk);
-+				bbr->full_bw = ctx->sample_bw;
-+			} else if (bbr->full_bw_now) {
-+				/* Plateau in estimated bw. Pipe looks full. */
-+				is_bw_probe_done = true;
-+			}
-+		}
-+		if (is_bw_probe_done) {
-+			bbr->prev_probe_too_high = 0;  /* no loss/ECN (yet) */
-+			bbr_start_bw_probe_down(sk);  /* restart w/ down */
-+		}
-+		break;
-+
-+	/* After probing in PROBE_UP, we have usually accumulated some data in
-+	 * the bottleneck buffer (if bw probing didn't find more bw). We next
-+	 * enter PROBE_DOWN to try to drain any excess data from the queue. To
-+	 * do this, we use a pacing_gain < 1.0. We hold this pacing gain until
-+	 * our inflight is less then that target cruising point, which is the
-+	 * minimum of (a) the amount needed to leave headroom, and (b) the
-+	 * estimated BDP. Once inflight falls to match the target, we estimate
-+	 * the queue is drained; persisting would underutilize the pipe.
-+	 */
-+	case BBR_BW_PROBE_DOWN:
-+		if (bbr_check_time_to_probe_bw(sk, rs))
-+			return;		/* already decided state transition */
-+		if (bbr_check_time_to_cruise(sk, inflight, bw))
-+			bbr_start_bw_probe_cruise(sk);
-+		break;
-+
-+	default:
-+		WARN_ONCE(1, "BBR invalid cycle index %u\n", bbr->cycle_idx);
-+	}
-+}
-+
-+/* Exiting PROBE_RTT, so return to bandwidth probing in STARTUP or PROBE_BW. */
-+static void bbr_exit_probe_rtt(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_lower_bounds(sk);
-+	if (bbr_full_bw_reached(sk)) {
-+		bbr->mode = BBR_PROBE_BW;
-+		/* Raising inflight after PROBE_RTT may cause loss, so reset
-+		 * the PROBE_BW clock and schedule the next bandwidth probe for
-+		 * a friendly and randomized future point in time.
-+		 */
-+		bbr_start_bw_probe_down(sk);
-+		/* Since we are exiting PROBE_RTT, we know inflight is
-+		 * below our estimated BDP, so it is reasonable to cruise.
-+		 */
-+		bbr_start_bw_probe_cruise(sk);
-+	} else {
-+		bbr->mode = BBR_STARTUP;
-+	}
-+}
-+
-+/* Exit STARTUP based on loss rate > 1% and loss gaps in round >= N. Wait until
-+ * the end of the round in recovery to get a good estimate of how many packets
-+ * have been lost, and how many we need to drain with a low pacing rate.
-+ */
-+static void bbr_check_loss_too_high_in_startup(struct sock *sk,
-+						const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr_full_bw_reached(sk))
-+		return;
-+
-+	/* For STARTUP exit, check the loss rate at the end of each round trip
-+	 * of Recovery episodes in STARTUP. We check the loss rate at the end
-+	 * of the round trip to filter out noisy/low loss and have a better
-+	 * sense of inflight (extent of loss), so we can drain more accurately.
-+	 */
-+	if (rs->losses && bbr->loss_events_in_round < 0xf)
-+		bbr->loss_events_in_round++;  /* update saturating counter */
-+	if (bbr_param(sk, full_loss_cnt) && bbr->loss_round_start &&
-+	    inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery &&
-+	    bbr->loss_events_in_round >= bbr_param(sk, full_loss_cnt) &&
-+	    bbr_is_inflight_too_high(sk, rs)) {
-+		bbr_handle_queue_too_high_in_startup(sk);
-+		return;
-+	}
-+	if (bbr->loss_round_start)
-+		bbr->loss_events_in_round = 0;
-+}
-+
-+/* Estimate when the pipe is full, using the change in delivery rate: BBR
-+ * estimates bw probing filled the pipe if the estimated bw hasn't changed by
-+ * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited
-+ * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the
-+ * higher rwin, 3: we get higher delivery rate samples. Or transient
-+ * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar
-+ * design goal, but uses delay and inter-ACK spacing instead of bandwidth.
-+ */
-+static void bbr_check_full_bw_reached(struct sock *sk,
-+				       const struct rate_sample *rs,
-+				       struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bw_thresh, full_cnt, thresh;
-+
-+	if (bbr->full_bw_now || rs->is_app_limited)
-+		return;
-+
-+	thresh = bbr_param(sk, full_bw_thresh);
-+	full_cnt = bbr_param(sk, full_bw_cnt);
-+	bw_thresh = (u64)bbr->full_bw * thresh >> BBR_SCALE;
-+	if (ctx->sample_bw >= bw_thresh) {
-+		bbr_reset_full_bw(sk);
-+		bbr->full_bw = ctx->sample_bw;
-+		return;
-+	}
-+	if (!bbr->round_start)
-+		return;
-+	++bbr->full_bw_cnt;
-+	bbr->full_bw_now = bbr->full_bw_cnt >= full_cnt;
-+	bbr->full_bw_reached |= bbr->full_bw_now;
-+}
-+
-+/* If pipe is probably full, drain the queue and then enter steady-state. */
-+static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs,
-+			    struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) {
-+		bbr->mode = BBR_DRAIN;	/* drain queue we created */
-+		/* Set ssthresh to export purely for monitoring, to signal
-+		 * completion of initial STARTUP by setting to a non-
-+		 * TCP_INFINITE_SSTHRESH value (ssthresh is not used by BBR).
-+		 */
-+		tcp_sk(sk)->snd_ssthresh =
-+				bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+		bbr_reset_congestion_signals(sk);
-+	}	/* fall through to check if in-flight is already small: */
-+	if (bbr->mode == BBR_DRAIN &&
-+	    bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <=
-+	    bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) {
-+		bbr->mode = BBR_PROBE_BW;
-+		bbr_start_bw_probe_down(sk);
-+	}
-+}
-+
-+static void bbr_update_model(struct sock *sk, const struct rate_sample *rs,
-+			      struct bbr_context *ctx)
-+{
-+	bbr_update_congestion_signals(sk, rs, ctx);
-+	bbr_update_ack_aggregation(sk, rs);
-+	bbr_check_loss_too_high_in_startup(sk, rs);
-+	bbr_check_full_bw_reached(sk, rs, ctx);
-+	bbr_check_drain(sk, rs, ctx);
-+	bbr_update_cycle_phase(sk, rs, ctx);
-+	bbr_update_min_rtt(sk, rs);
-+}
-+
-+/* Fast path for app-limited case.
-+ *
-+ * On each ack, we execute bbr state machine, which primarily consists of:
-+ * 1) update model based on new rate sample, and
-+ * 2) update control based on updated model or state change.
-+ *
-+ * There are certain workload/scenarios, e.g. app-limited case, where
-+ * either we can skip updating model or we can skip update of both model
-+ * as well as control. This provides signifcant softirq cpu savings for
-+ * processing incoming acks.
-+ *
-+ * In case of app-limited, if there is no congestion (loss/ecn) and
-+ * if observed bw sample is less than current estimated bw, then we can
-+ * skip some of the computation in bbr state processing:
-+ *
-+ * - if there is no rtt/mode/phase change: In this case, since all the
-+ *   parameters of the network model are constant, we can skip model
-+ *   as well control update.
-+ *
-+ * - else we can skip rest of the model update. But we still need to
-+ *   update the control to account for the new rtt/mode/phase.
-+ *
-+ * Returns whether we can take fast path or not.
-+ */
-+static bool bbr_run_fast_path(struct sock *sk, bool *update_model,
-+		const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 prev_min_rtt_us, prev_mode;
-+
-+	if (bbr_param(sk, fast_path) && bbr->try_fast_path &&
-+	    rs->is_app_limited && ctx->sample_bw < bbr_max_bw(sk) &&
-+	    !bbr->loss_in_round && !bbr->ecn_in_round ) {
-+		prev_mode = bbr->mode;
-+		prev_min_rtt_us = bbr->min_rtt_us;
-+		bbr_check_drain(sk, rs, ctx);
-+		bbr_update_cycle_phase(sk, rs, ctx);
-+		bbr_update_min_rtt(sk, rs);
-+
-+		if (bbr->mode == prev_mode &&
-+		    bbr->min_rtt_us == prev_min_rtt_us &&
-+		    bbr->try_fast_path) {
-+			return true;
-+		}
-+
-+		/* Skip model update, but control still needs to be updated */
-+		*update_model = false;
-+	}
-+	return false;
-+}
-+
-+static void bbr_main(struct sock *sk, u32 ack, int flag,
-+		     const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct bbr_context ctx = { 0 };
-+	bool update_model = true;
-+	u32 bw, round_delivered;
-+	int ce_ratio = -1;
-+
-+	round_delivered = bbr_update_round_start(sk, rs, &ctx);
-+	if (bbr->round_start) {
-+		bbr->rounds_since_probe =
-+			min_t(s32, bbr->rounds_since_probe + 1, 0xFF);
-+		ce_ratio = bbr_update_ecn_alpha(sk);
-+	}
-+	bbr_plb(sk, rs, ce_ratio);
-+
-+	bbr->ecn_in_round  |= (bbr->ecn_eligible && rs->is_ece);
-+	bbr_calculate_bw_sample(sk, rs, &ctx);
-+	bbr_update_latest_delivery_signals(sk, rs, &ctx);
-+
-+	if (bbr_run_fast_path(sk, &update_model, rs, &ctx))
-+		goto out;
-+
-+	if (update_model)
-+		bbr_update_model(sk, rs, &ctx);
-+
-+	bbr_update_gains(sk);
-+	bw = bbr_bw(sk);
-+	bbr_set_pacing_rate(sk, bw, bbr->pacing_gain);
-+	bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain,
-+		     tcp_snd_cwnd(tp), &ctx);
-+	bbr_bound_cwnd_for_inflight_model(sk);
-+
-+out:
-+	bbr_advance_latest_delivery_signals(sk, rs, &ctx);
-+	bbr->prev_ca_state = inet_csk(sk)->icsk_ca_state;
-+	bbr->loss_in_cycle |= rs->lost > 0;
-+	bbr->ecn_in_cycle  |= rs->delivered_ce > 0;
-+}
-+
-+static void bbr_init(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->initialized = 1;
-+
-+	bbr->init_cwnd = min(0x7FU, tcp_snd_cwnd(tp));
-+	bbr->prior_cwnd = tp->prior_cwnd;
-+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr->prev_ca_state = TCP_CA_Open;
-+
-+	bbr->probe_rtt_done_stamp = 0;
-+	bbr->probe_rtt_round_done = 0;
-+	bbr->probe_rtt_min_us = tcp_min_rtt(tp);
-+	bbr->probe_rtt_min_stamp = tcp_jiffies32;
-+	bbr->min_rtt_us = tcp_min_rtt(tp);
-+	bbr->min_rtt_stamp = tcp_jiffies32;
-+
-+	bbr->has_seen_rtt = 0;
-+	bbr_init_pacing_rate_from_rtt(sk);
-+
-+	bbr->round_start = 0;
-+	bbr->idle_restart = 0;
-+	bbr->full_bw_reached = 0;
-+	bbr->full_bw = 0;
- 	bbr->full_bw_cnt = 0;
--	bbr_reset_lt_bw_sampling(sk);
--	return tcp_snd_cwnd(tcp_sk(sk));
-+	bbr->cycle_mstamp = 0;
-+	bbr->cycle_idx = 0;
-+
-+	bbr_reset_startup_mode(sk);
-+
-+	bbr->ack_epoch_mstamp = tp->tcp_mstamp;
-+	bbr->ack_epoch_acked = 0;
-+	bbr->extra_acked_win_rtts = 0;
-+	bbr->extra_acked_win_idx = 0;
-+	bbr->extra_acked[0] = 0;
-+	bbr->extra_acked[1] = 0;
-+
-+	bbr->ce_state = 0;
-+	bbr->prior_rcv_nxt = tp->rcv_nxt;
-+	bbr->try_fast_path = 0;
-+
-+	cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED);
-+
-+	/* Start sampling ECN mark rate after first full flight is ACKed: */
-+	bbr->loss_round_delivered = tp->delivered + 1;
-+	bbr->loss_round_start = 0;
-+	bbr->undo_bw_lo = 0;
-+	bbr->undo_inflight_lo = 0;
-+	bbr->undo_inflight_hi = 0;
-+	bbr->loss_events_in_round = 0;
-+	bbr->startup_ecn_rounds = 0;
-+	bbr_reset_congestion_signals(sk);
-+	bbr->bw_lo = ~0U;
-+	bbr->bw_hi[0] = 0;
-+	bbr->bw_hi[1] = 0;
-+	bbr->inflight_lo = ~0U;
-+	bbr->inflight_hi = ~0U;
-+	bbr_reset_full_bw(sk);
-+	bbr->bw_probe_up_cnt = ~0U;
-+	bbr->bw_probe_up_acks = 0;
-+	bbr->bw_probe_up_rounds = 0;
-+	bbr->probe_wait_us = 0;
-+	bbr->stopped_risky_probe = 0;
-+	bbr->ack_phase = BBR_ACKS_INIT;
-+	bbr->rounds_since_probe = 0;
-+	bbr->bw_probe_samples = 0;
-+	bbr->prev_probe_too_high = 0;
-+	bbr->ecn_eligible = 0;
-+	bbr->ecn_alpha = bbr_param(sk, ecn_alpha_init);
-+	bbr->alpha_last_delivered = 0;
-+	bbr->alpha_last_delivered_ce = 0;
-+	bbr->plb.pause_until = 0;
-+
-+	tp->fast_ack_mode = bbr_fast_ack_mode ? 1 : 0;
-+
-+	if (bbr_can_use_ecn(sk))
-+		tp->ecn_flags |= TCP_ECN_ECT_PERMANENT;
-+}
-+
-+/* BBR marks the current round trip as a loss round. */
-+static void bbr_note_loss(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Capture "current" data over the full round trip of loss, to
-+	 * have a better chance of observing the full capacity of the path.
-+	 */
-+	if (!bbr->loss_in_round)  /* first loss in this round trip? */
-+		bbr->loss_round_delivered = tp->delivered;  /* set round trip */
-+	bbr->loss_in_round = 1;
-+	bbr->loss_in_cycle = 1;
-+}
-+
-+/* Core TCP stack informs us that the given skb was just marked lost. */
-+static void bbr_skb_marked_lost(struct sock *sk,
-+				const struct sk_buff *skb)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
-+	struct rate_sample rs = {};
-+
-+	bbr_note_loss(sk);
-+
-+	if (!bbr->bw_probe_samples)
-+		return;  /* not an skb sent while probing for bandwidth */
-+	if (unlikely(!scb->tx.delivered_mstamp))
-+		return;  /* skb was SACKed, reneged, marked lost; ignore it */
-+	/* We are probing for bandwidth. Construct a rate sample that
-+	 * estimates what happened in the flight leading up to this lost skb,
-+	 * then see if the loss rate went too high, and if so at which packet.
-+	 */
-+	rs.tx_in_flight = scb->tx.in_flight;
-+	rs.lost = tp->lost - scb->tx.lost;
-+	rs.is_app_limited = scb->tx.is_app_limited;
-+	if (bbr_is_inflight_too_high(sk, &rs)) {
-+		rs.tx_in_flight = bbr_inflight_hi_from_lost_skb(sk, &rs, skb);
-+		bbr_handle_inflight_too_high(sk, &rs);
-+	}
- }
- 
--/* Entering loss recovery, so save cwnd for when we exit or undo recovery. */
-+static void bbr_run_loss_probe_recovery(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct rate_sample rs = {0};
-+
-+	bbr_note_loss(sk);
-+
-+	if (!bbr->bw_probe_samples)
-+		return;  /* not sent while probing for bandwidth */
-+	/* We are probing for bandwidth. Construct a rate sample that
-+	 * estimates what happened in the flight leading up to this
-+	 * loss, then see if the loss rate went too high.
-+	 */
-+	rs.lost = 1;	/* TLP probe repaired loss of a single segment */
-+	rs.tx_in_flight = bbr->inflight_latest + rs.lost;
-+	rs.is_app_limited = tp->tlp_orig_data_app_limited;
-+	if (bbr_is_inflight_too_high(sk, &rs))
-+		bbr_handle_inflight_too_high(sk, &rs);
-+}
-+
-+/* Revert short-term model if current loss recovery event was spurious. */
-+static u32 bbr_undo_cwnd(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_full_bw(sk); /* spurious slow-down; reset full bw detector */
-+	bbr->loss_in_round = 0;
-+
-+	/* Revert to cwnd and other state saved before loss episode. */
-+	bbr->bw_lo = max(bbr->bw_lo, bbr->undo_bw_lo);
-+	bbr->inflight_lo = max(bbr->inflight_lo, bbr->undo_inflight_lo);
-+	bbr->inflight_hi = max(bbr->inflight_hi, bbr->undo_inflight_hi);
-+	bbr->try_fast_path = 0;  /* take slow path to set proper cwnd, pacing */
-+	return bbr->prior_cwnd;
-+}
-+
-+/* Entering loss recovery, so save state for when we undo recovery. */
- static u32 bbr_ssthresh(struct sock *sk)
- {
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
- 	bbr_save_cwnd(sk);
-+	/* For undo, save state that adapts based on loss signal. */
-+	bbr->undo_bw_lo		= bbr->bw_lo;
-+	bbr->undo_inflight_lo	= bbr->inflight_lo;
-+	bbr->undo_inflight_hi	= bbr->inflight_hi;
- 	return tcp_sk(sk)->snd_ssthresh;
- }
- 
-+static enum tcp_bbr_phase bbr_get_phase(struct bbr *bbr)
-+{
-+	switch (bbr->mode) {
-+	case BBR_STARTUP:
-+		return BBR_PHASE_STARTUP;
-+	case BBR_DRAIN:
-+		return BBR_PHASE_DRAIN;
-+	case BBR_PROBE_BW:
-+		break;
-+	case BBR_PROBE_RTT:
-+		return BBR_PHASE_PROBE_RTT;
-+	default:
-+		return BBR_PHASE_INVALID;
-+	}
-+	switch (bbr->cycle_idx) {
-+	case BBR_BW_PROBE_UP:
-+		return BBR_PHASE_PROBE_BW_UP;
-+	case BBR_BW_PROBE_DOWN:
-+		return BBR_PHASE_PROBE_BW_DOWN;
-+	case BBR_BW_PROBE_CRUISE:
-+		return BBR_PHASE_PROBE_BW_CRUISE;
-+	case BBR_BW_PROBE_REFILL:
-+		return BBR_PHASE_PROBE_BW_REFILL;
-+	default:
-+		return BBR_PHASE_INVALID;
-+	}
-+}
-+
- static size_t bbr_get_info(struct sock *sk, u32 ext, int *attr,
--			   union tcp_cc_info *info)
-+			    union tcp_cc_info *info)
- {
- 	if (ext & (1 << (INET_DIAG_BBRINFO - 1)) ||
- 	    ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
--		struct tcp_sock *tp = tcp_sk(sk);
- 		struct bbr *bbr = inet_csk_ca(sk);
--		u64 bw = bbr_bw(sk);
--
--		bw = bw * tp->mss_cache * USEC_PER_SEC >> BW_SCALE;
--		memset(&info->bbr, 0, sizeof(info->bbr));
--		info->bbr.bbr_bw_lo		= (u32)bw;
--		info->bbr.bbr_bw_hi		= (u32)(bw >> 32);
--		info->bbr.bbr_min_rtt		= bbr->min_rtt_us;
--		info->bbr.bbr_pacing_gain	= bbr->pacing_gain;
--		info->bbr.bbr_cwnd_gain		= bbr->cwnd_gain;
-+		u64 bw = bbr_bw_bytes_per_sec(sk, bbr_bw(sk));
-+		u64 bw_hi = bbr_bw_bytes_per_sec(sk, bbr_max_bw(sk));
-+		u64 bw_lo = bbr->bw_lo == ~0U ?
-+			~0ULL : bbr_bw_bytes_per_sec(sk, bbr->bw_lo);
-+		struct tcp_bbr_info *bbr_info = &info->bbr;
-+
-+		memset(bbr_info, 0, sizeof(*bbr_info));
-+		bbr_info->bbr_bw_lo		= (u32)bw;
-+		bbr_info->bbr_bw_hi		= (u32)(bw >> 32);
-+		bbr_info->bbr_min_rtt		= bbr->min_rtt_us;
-+		bbr_info->bbr_pacing_gain	= bbr->pacing_gain;
-+		bbr_info->bbr_cwnd_gain		= bbr->cwnd_gain;
-+		bbr_info->bbr_bw_hi_lsb		= (u32)bw_hi;
-+		bbr_info->bbr_bw_hi_msb		= (u32)(bw_hi >> 32);
-+		bbr_info->bbr_bw_lo_lsb		= (u32)bw_lo;
-+		bbr_info->bbr_bw_lo_msb		= (u32)(bw_lo >> 32);
-+		bbr_info->bbr_mode		= bbr->mode;
-+		bbr_info->bbr_phase		= (__u8)bbr_get_phase(bbr);
-+		bbr_info->bbr_version		= (__u8)BBR_VERSION;
-+		bbr_info->bbr_inflight_lo	= bbr->inflight_lo;
-+		bbr_info->bbr_inflight_hi	= bbr->inflight_hi;
-+		bbr_info->bbr_extra_acked	= bbr_extra_acked(sk);
- 		*attr = INET_DIAG_BBRINFO;
--		return sizeof(info->bbr);
-+		return sizeof(*bbr_info);
- 	}
- 	return 0;
- }
- 
- static void bbr_set_state(struct sock *sk, u8 new_state)
- {
-+	struct tcp_sock *tp = tcp_sk(sk);
- 	struct bbr *bbr = inet_csk_ca(sk);
- 
- 	if (new_state == TCP_CA_Loss) {
--		struct rate_sample rs = { .losses = 1 };
- 
- 		bbr->prev_ca_state = TCP_CA_Loss;
--		bbr->full_bw = 0;
--		bbr->round_start = 1;	/* treat RTO like end of a round */
--		bbr_lt_bw_sampling(sk, &rs);
-+		tcp_plb_update_state_upon_rto(sk, &bbr->plb);
-+		/* The tcp_write_timeout() call to sk_rethink_txhash() likely
-+		 * repathed this flow, so re-learn the min network RTT on the
-+		 * new path:
-+		 */
-+		bbr_reset_full_bw(sk);
-+		if (!bbr_is_probing_bandwidth(sk) && bbr->inflight_lo == ~0U) {
-+			/* bbr_adapt_lower_bounds() needs cwnd before
-+			 * we suffered an RTO, to update inflight_lo:
-+			 */
-+			bbr->inflight_lo =
-+				max(tcp_snd_cwnd(tp), bbr->prior_cwnd);
-+		}
-+	} else if (bbr->prev_ca_state == TCP_CA_Loss &&
-+		   new_state != TCP_CA_Loss) {
-+		bbr_exit_loss_recovery(sk);
- 	}
- }
- 
-+
- static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = {
--	.flags		= TCP_CONG_NON_RESTRICTED,
-+	.flags		= TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS,
- 	.name		= "bbr",
- 	.owner		= THIS_MODULE,
- 	.init		= bbr_init,
- 	.cong_control	= bbr_main,
- 	.sndbuf_expand	= bbr_sndbuf_expand,
-+	.skb_marked_lost = bbr_skb_marked_lost,
- 	.undo_cwnd	= bbr_undo_cwnd,
- 	.cwnd_event	= bbr_cwnd_event,
- 	.ssthresh	= bbr_ssthresh,
--	.min_tso_segs	= bbr_min_tso_segs,
-+	.tso_segs	= bbr_tso_segs,
- 	.get_info	= bbr_get_info,
- 	.set_state	= bbr_set_state,
- };
- 
--BTF_SET8_START(tcp_bbr_check_kfunc_ids)
--#ifdef CONFIG_X86
--#ifdef CONFIG_DYNAMIC_FTRACE
-+#ifdef CONFIG_BPF_SYSCALL
-+BTF_KFUNCS_START(tcp_bbr_check_kfunc_ids)
- BTF_ID_FLAGS(func, bbr_init)
- BTF_ID_FLAGS(func, bbr_main)
- BTF_ID_FLAGS(func, bbr_sndbuf_expand)
-+BTF_ID_FLAGS(func, bbr_skb_marked_lost)
- BTF_ID_FLAGS(func, bbr_undo_cwnd)
- BTF_ID_FLAGS(func, bbr_cwnd_event)
- BTF_ID_FLAGS(func, bbr_ssthresh)
--BTF_ID_FLAGS(func, bbr_min_tso_segs)
-+BTF_ID_FLAGS(func, bbr_tso_segs)
- BTF_ID_FLAGS(func, bbr_set_state)
--#endif
--#endif
--BTF_SET8_END(tcp_bbr_check_kfunc_ids)
-+BTF_KFUNCS_END(tcp_bbr_check_kfunc_ids)
- 
- static const struct btf_kfunc_id_set tcp_bbr_kfunc_set = {
- 	.owner = THIS_MODULE,
- 	.set   = &tcp_bbr_check_kfunc_ids,
- };
-+#endif
- 
- static int __init bbr_register(void)
- {
-@@ -1180,9 +2381,11 @@ static int __init bbr_register(void)
- 
- 	BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE);
- 
-+#ifdef CONFIG_BPF_SYSCALL
- 	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &tcp_bbr_kfunc_set);
- 	if (ret < 0)
- 		return ret;
-+#endif
- 	return tcp_register_congestion_control(&tcp_bbr_cong_ops);
- }
- 
-@@ -1198,5 +2401,12 @@ MODULE_AUTHOR("Van Jacobson <vanj@google.com>");
- MODULE_AUTHOR("Neal Cardwell <ncardwell@google.com>");
- MODULE_AUTHOR("Yuchung Cheng <ycheng@google.com>");
- MODULE_AUTHOR("Soheil Hassas Yeganeh <soheil@google.com>");
-+MODULE_AUTHOR("Priyaranjan Jha <priyarjha@google.com>");
-+MODULE_AUTHOR("Yousuk Seung <ysseung@google.com>");
-+MODULE_AUTHOR("Kevin Yang <yyd@google.com>");
-+MODULE_AUTHOR("Arjun Roy <arjunroy@google.com>");
-+MODULE_AUTHOR("David Morley <morleyd@google.com>");
-+
- MODULE_LICENSE("Dual BSD/GPL");
- MODULE_DESCRIPTION("TCP BBR (Bottleneck Bandwidth and RTT)");
-+MODULE_VERSION(__stringify(BBR_VERSION));

.github/actions/networking/patches/bbrv3.patch

@@ -1,2604 +0,0 @@
-diff --git a/include/net/tcp.h b/include/net/tcp.h
-index afe1ca2cc..8eebfafdd 100644
---- a/include/net/tcp.h
-+++ b/include/net/tcp.h
-@@ -1112,6 +1112,12 @@ struct tcp_congestion_ops {
- 	/* override sysctl_tcp_min_tso_segs */
- 	u32 (*min_tso_segs)(struct sock *sk);
- 
-+	/* call when skb is marked lost (optional) */
-+	void (*skb_marked_lost)(struct sock *sk, const struct sk_buff *skb);
-+
-+	/* set TSO segment count (optional, for new congestion controls) */
-+	u32 (*tso_segs)(struct sock *sk, unsigned int mss_now);
-+
- 	/* call when packets are delivered to update cwnd and pacing rate,
- 	 * after all the ca_state processing. (optional)
- 	 */
-diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
-index 50655de04..8d69bd9b7 100644
---- a/include/uapi/linux/inet_diag.h
-+++ b/include/uapi/linux/inet_diag.h
-@@ -223,12 +223,37 @@ struct tcp_dctcp_info {
- /* INET_DIAG_BBRINFO */
- 
- struct tcp_bbr_info {
-+	/* Original 6 fields - unchanged offsets for ABI backward compatibility */
- 	/* u64 bw: max-filtered BW (app throughput) estimate in Byte per sec: */
- 	__u32	bbr_bw_lo;		/* lower 32 bits of bw */
- 	__u32	bbr_bw_hi;		/* upper 32 bits of bw */
- 	__u32	bbr_min_rtt;		/* min-filtered RTT in uSec */
- 	__u32	bbr_pacing_gain;	/* pacing gain shifted left 8 bits */
- 	__u32	bbr_cwnd_gain;		/* cwnd gain shifted left 8 bits */
-+	/* BBRv3+ new fields - appended for extended information */
-+	__u32	bbr_bw_hi_lsb;		/* lower 32 bits of bw_hi */
-+	__u32	bbr_bw_hi_msb;		/* upper 32 bits of bw_hi */
-+	__u32	bbr_bw_lo_lsb;		/* lower 32 bits of bw_lo */
-+	__u32	bbr_bw_lo_msb;		/* upper 32 bits of bw_lo */
-+	__u8	bbr_mode;		/* current bbr_mode in state machine */
-+	__u8	bbr_phase;		/* current state machine phase */
-+	__u8	unused1;		/* alignment padding; not used yet */
-+	__u8	bbr_version;		/* BBR algorithm version */
-+	__u32	bbr_inflight_lo;	/* lower short-term data volume bound */
-+	__u32	bbr_inflight_hi;	/* higher long-term data volume bound */
-+	__u32	bbr_extra_acked;	/* max excess packets ACKed in epoch */
-+};
-+
-+/* TCP BBR congestion control bbr_phase as reported in netlink/ss stats */
-+enum tcp_bbr_phase {
-+	BBR_PHASE_INVALID		= 0,
-+	BBR_PHASE_STARTUP		= 1,
-+	BBR_PHASE_DRAIN			= 2,
-+	BBR_PHASE_PROBE_RTT		= 3,
-+	BBR_PHASE_PROBE_BW_UP		= 4,
-+	BBR_PHASE_PROBE_BW_DOWN		= 5,
-+	BBR_PHASE_PROBE_BW_CRUISE	= 6,
-+	BBR_PHASE_PROBE_BW_REFILL	= 7,
- };
- 
- union tcp_cc_info {
-diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
-index 2dfb12230..afc41f6f7 100644
---- a/net/ipv4/Kconfig
-+++ b/net/ipv4/Kconfig
-@@ -678,6 +678,27 @@ config TCP_CONG_BBR
- 	  AQM schemes that do not provide a delay signal. It requires the fq
- 	  ("Fair Queue") pacing packet scheduler.
- 
-+config TCP_CONG_BBRV3
-+	bool "BBRv3 TCP"
-+	default y
-+	depends on TCP_CONG_BBR || TCP_CONG_BBR=y
-+	help
-+	  BBRv3 (Bottleneck Bandwidth and RTT version 3) TCP congestion
-+	  control. This is an enhanced version of BBR with improved
-+	  fairness, ECN support, and loss handling.
-+
-+	  BBRv3 builds on BBRv1 with additional features:
-+	    - Rate probing with bounded risk of loss
-+	    - ECN-aware congestion avoidance
-+	    - Improved fairness with Reno/CUBIC flows
-+	    - Loss detection and recovery improvements
-+
-+	  To use this module, you must also have:
-+	    - FQ pacing scheduler (CONFIG_NET_SCH_FQ)
-+	    - Optionally: ECN support (CONFIG_TCP_ECN)
-+
-+	  If unsure, say Y.
-+
- choice
- 	prompt "Default TCP congestion control"
- 	default DEFAULT_CUBIC
-@@ -715,6 +736,9 @@ choice
- 	config DEFAULT_BBR
- 		bool "BBR" if TCP_CONG_BBR=y
- 
-+	config DEFAULT_BBRV3
-+		bool "BBRv3" if TCP_CONG_BBRV3=y
-+
- 	config DEFAULT_RENO
- 		bool "Reno"
- endchoice
-@@ -739,6 +763,7 @@ config DEFAULT_TCP_CONG
- 	default "dctcp" if DEFAULT_DCTCP
- 	default "cdg" if DEFAULT_CDG
- 	default "bbr" if DEFAULT_BBR
-+	default "bbrv3" if DEFAULT_BBRV3
- 	default "cubic"
- 
- config TCP_MD5SIG
-diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
-index bbdd9c44f..bd5d416a4 100644
---- a/net/ipv4/Makefile
-+++ b/net/ipv4/Makefile
-@@ -46,6 +46,7 @@ obj-$(CONFIG_INET_TCP_DIAG) += tcp_diag.o
- obj-$(CONFIG_INET_UDP_DIAG) += udp_diag.o
- obj-$(CONFIG_INET_RAW_DIAG) += raw_diag.o
- obj-$(CONFIG_TCP_CONG_BBR) += tcp_bbr.o
-+obj-$(CONFIG_TCP_CONG_BBRV3) += tcp_bbrv3.o
- obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
- obj-$(CONFIG_TCP_CONG_CDG) += tcp_cdg.o
- obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o
-diff --git a/net/ipv4/tcp_dctcp.h b/net/ipv4/tcp_dctcp.h
-index d69a77cbd..b99744ea9 100644
---- a/net/ipv4/tcp_dctcp.h
-+++ b/net/ipv4/tcp_dctcp.h
-@@ -1,6 +1,14 @@
-+/* SPDX-License-Identifier: GPL-2.0 */
- #ifndef _TCP_DCTCP_H
- #define _TCP_DCTCP_H
- 
-+/*
-+ * DCTCP ECE ACK helper functions for BBRv3
-+ *
-+ * These functions implement the minimal DCTP CE state machine needed
-+ * by BBRv3 for ECN-based congestion avoidance.
-+ */
-+
- static inline void dctcp_ece_ack_cwr(struct sock *sk, u32 ce_state)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
-@@ -37,4 +45,41 @@ static inline void dctcp_ece_ack_update(struct sock *sk, enum tcp_ca_event evt,
- 	dctcp_ece_ack_cwr(sk, new_ce_state);
- }
- 
--#endif
-+/*
-+ * State for PLB (Protective Load Balancing) for a single TCP connection.
-+ * PLB is an optional feature for datacenter load balancing.
-+ */
-+struct tcp_plb_state {
-+	u8	consec_cong_rounds:5, /* consecutive congested rounds */
-+		pause_until_set:1;	/* pause_until is valid */
-+	u32	pause_until;		/* don't rehash until this jiffie */
-+};
-+
-+static inline void tcp_plb_init(const struct sock *sk,
-+				struct tcp_plb_state *plb)
-+{
-+	memset(plb, 0, sizeof(*plb));
-+}
-+
-+static inline void tcp_plb_update_state(const struct sock *sk,
-+					struct tcp_plb_state *plb,
-+					const int cong_ratio)
-+{
-+	/* PLB is optional - stub implementation for kernels without
-+	 * the full PLB infrastructure (sysctl_tcp_plb_enabled, etc.)
-+	 */
-+}
-+
-+static inline void tcp_plb_check_rehash(struct sock *sk,
-+					struct tcp_plb_state *plb)
-+{
-+	/* Stub - PLB rehash not available without full infrastructure */
-+}
-+
-+static inline void tcp_plb_update_state_upon_rto(struct sock *sk,
-+						 struct tcp_plb_state *plb)
-+{
-+	/* Stub - RTO state update not available without full infrastructure */
-+}
-+
-+#endif /* _TCP_DCTCP_H */
-diff --git a/net/ipv4/tcp_bbrv3.c b/net/ipv4/tcp_bbrv3.c
-new file mode 100644
-index 000000000..b7e8825e1
---- /dev/null
-+++ b/net/ipv4/tcp_bbrv3.c
-@@ -0,0 +1,2415 @@
-+/* BBR (Bottleneck Bandwidth and RTT) congestion control
-+ *
-+ * BBR is a model-based congestion control algorithm that aims for low queues,
-+ * low loss, and (bounded) Reno/CUBIC coexistence. To maintain a model of the
-+ * network path, it uses measurements of bandwidth and RTT, as well as (if they
-+ * occur) packet loss and/or shallow-threshold ECN signals. Note that although
-+ * it can use ECN or loss signals explicitly, it does not require either; it
-+ * can bound its in-flight data based on its estimate of the BDP.
-+ *
-+ * The model has both higher and lower bounds for the operating range:
-+ *   lo: bw_lo, inflight_lo: conservative short-term lower bound
-+ *   hi: bw_hi, inflight_hi: robust long-term upper bound
-+ * The bandwidth-probing time scale is (a) extended dynamically based on
-+ * estimated BDP to improve coexistence with Reno/CUBIC; (b) bounded by
-+ * an interactive wall-clock time-scale to be more scalable and responsive
-+ * than Reno and CUBIC.
-+ *
-+ * Here is a state transition diagram for BBR:
-+ *
-+ *             |
-+ *             V
-+ *    +---> STARTUP  ----+
-+ *    |        |         |
-+ *    |        V         |
-+ *    |      DRAIN   ----+
-+ *    |        |         |
-+ *    |        V         |
-+ *    +---> PROBE_BW ----+
-+ *    |      ^    |      |
-+ *    |      |    |      |
-+ *    |      +----+      |
-+ *    |                  |
-+ *    +---- PROBE_RTT <--+
-+ *
-+ * A BBR flow starts in STARTUP, and ramps up its sending rate quickly.
-+ * When it estimates the pipe is full, it enters DRAIN to drain the queue.
-+ * In steady state a BBR flow only uses PROBE_BW and PROBE_RTT.
-+ * A long-lived BBR flow spends the vast majority of its time remaining
-+ * (repeatedly) in PROBE_BW, fully probing and utilizing the pipe's bandwidth
-+ * in a fair manner, with a small, bounded queue. *If* a flow has been
-+ * continuously sending for the entire min_rtt window, and hasn't seen an RTT
-+ * sample that matches or decreases its min_rtt estimate for 10 seconds, then
-+ * it briefly enters PROBE_RTT to cut inflight to a minimum value to re-probe
-+ * the path's two-way propagation delay (min_rtt). When exiting PROBE_RTT, if
-+ * we estimated that we reached the full bw of the pipe then we enter PROBE_BW;
-+ * otherwise we enter STARTUP to try to fill the pipe.
-+ *
-+ * BBR is described in detail in:
-+ *   "BBR: Congestion-Based Congestion Control",
-+ *   Neal Cardwell, Yuchung Cheng, C. Stephen Gunn, Soheil Hassas Yeganeh,
-+ *   Van Jacobson. ACM Queue, Vol. 14 No. 5, September-October 2016.
-+ *
-+ * There is a public e-mail list for discussing BBR development and testing:
-+ *   https://groups.google.com/forum/#!forum/bbr-dev
-+ *
-+ * NOTE: BBR might be used with the fq qdisc ("man tc-fq") with pacing enabled,
-+ * otherwise TCP stack falls back to an internal pacing using one high
-+ * resolution timer per TCP socket and may use more resources.
-+ */
-+#include <linux/btf.h>
-+#include <linux/btf_ids.h>
-+#include <linux/module.h>
-+#include <net/tcp.h>
-+#include <linux/inet_diag.h>
-+#include <linux/inet.h>
-+#include <linux/random.h>
-+#include <linux/win_minmax.h>
-+
-+#include <trace/events/tcp.h>
-+#include "tcp_dctcp.h"
-+
-+/* BTF kfunc compatibility macros for kernels that don't have the newer BTF API */
-+#ifndef BTF_KFUNCS_START
-+#define BTF_KFUNCS_START(name) BTF_SET8_START(name)
-+#define BTF_KFUNCS_END(name) BTF_SET8_END(name)
-+#define __bpf_kfunc static
-+#endif
-+
-+#define BBR_VERSION		3
-+
-+#define bbr_param(sk,name)	(bbr_ ## name)
-+
-+/* Scale factor for rate in pkt/uSec unit to avoid truncation in bandwidth
-+ * estimation. The rate unit ~= (1500 bytes / 1 usec / 2^24) ~= 715 bps.
-+ * This handles bandwidths from 0.06pps (715bps) to 256Mpps (3Tbps) in a u32.
-+ * Since the minimum window is >=4 packets, the lower bound isn't
-+ * an issue. The upper bound isn't an issue with existing technologies.
-+ */
-+#define BW_SCALE 24
-+#define BW_UNIT (1 << BW_SCALE)
-+
-+#define BBR_SCALE 8	/* scaling factor for fractions in BBR (e.g. gains) */
-+#define BBR_UNIT (1 << BBR_SCALE)
-+
-+/* BBR has the following modes for deciding how fast to send: */
-+enum bbr_mode {
-+	BBR_STARTUP,	/* ramp up sending rate rapidly to fill pipe */
-+	BBR_DRAIN,	/* drain any queue created during startup */
-+	BBR_PROBE_BW,	/* discover, share bw: pace around estimated bw */
-+	BBR_PROBE_RTT,	/* cut inflight to min to probe min_rtt */
-+};
-+
-+/* How does the incoming ACK stream relate to our bandwidth probing? */
-+enum bbr_ack_phase {
-+	BBR_ACKS_INIT,		  /* not probing; not getting probe feedback */
-+	BBR_ACKS_REFILLING,	  /* sending at est. bw to fill pipe */
-+	BBR_ACKS_PROBE_STARTING,  /* inflight rising to probe bw */
-+	BBR_ACKS_PROBE_FEEDBACK,  /* getting feedback from bw probing */
-+	BBR_ACKS_PROBE_STOPPING,  /* stopped probing; still getting feedback */
-+};
-+
-+/* BBR congestion control block */
-+struct bbr {
-+	u32	min_rtt_us;	        /* min RTT in min_rtt_win_sec window */
-+	u32	min_rtt_stamp;	        /* timestamp of min_rtt_us */
-+	u32	probe_rtt_done_stamp;   /* end time for BBR_PROBE_RTT mode */
-+	u32	probe_rtt_min_us;	/* min RTT in probe_rtt_win_ms win */
-+	u32	probe_rtt_min_stamp;	/* timestamp of probe_rtt_min_us*/
-+	u32     next_rtt_delivered; /* scb->tx.delivered at end of round */
-+	u64	cycle_mstamp;	     /* time of this cycle phase start */
-+	u32     mode:2,		     /* current bbr_mode in state machine */
-+		prev_ca_state:3,     /* CA state on previous ACK */
-+		round_start:1,	     /* start of packet-timed tx->ack round? */
-+		ce_state:1,          /* If most recent data has CE bit set */
-+		bw_probe_up_rounds:5,   /* cwnd-limited rounds in PROBE_UP */
-+		try_fast_path:1,	/* can we take fast path? */
-+		idle_restart:1,	     /* restarting after idle? */
-+		probe_rtt_round_done:1,  /* a BBR_PROBE_RTT round at 4 pkts? */
-+		init_cwnd:7,         /* initial cwnd */
-+		unused_1:10;
-+	u32	pacing_gain:10,	/* current gain for setting pacing rate */
-+		cwnd_gain:10,	/* current gain for setting cwnd */
-+		full_bw_reached:1,   /* reached full bw in Startup? */
-+		full_bw_cnt:2,	/* number of rounds without large bw gains */
-+		cycle_idx:2,	/* current index in pacing_gain cycle array */
-+		has_seen_rtt:1, /* have we seen an RTT sample yet? */
-+		unused_2:6;
-+	u32	prior_cwnd;	/* prior cwnd upon entering loss recovery */
-+	u32	full_bw;	/* recent bw, to estimate if pipe is full */
-+
-+	/* For tracking ACK aggregation: */
-+	u64	ack_epoch_mstamp;	/* start of ACK sampling epoch */
-+	u16	extra_acked[2];		/* max excess data ACKed in epoch */
-+	u32	ack_epoch_acked:20,	/* packets (S)ACKed in sampling epoch */
-+		extra_acked_win_rtts:5,	/* age of extra_acked, in round trips */
-+		extra_acked_win_idx:1,	/* current index in extra_acked array */
-+	/* BBR v3 state: */
-+		full_bw_now:1,		/* recently reached full bw plateau? */
-+		startup_ecn_rounds:2,	/* consecutive hi ECN STARTUP rounds */
-+		loss_in_cycle:1,	/* packet loss in this cycle? */
-+		ecn_in_cycle:1,		/* ECN in this cycle? */
-+		unused_3:1;
-+	u32	loss_round_delivered; /* scb->tx.delivered ending loss round */
-+	u32	undo_bw_lo;	     /* bw_lo before latest losses */
-+	u32	undo_inflight_lo;    /* inflight_lo before latest losses */
-+	u32	undo_inflight_hi;    /* inflight_hi before latest losses */
-+	u32	bw_latest;	 /* max delivered bw in last round trip */
-+	u32	bw_lo;		 /* lower bound on sending bandwidth */
-+	u32	bw_hi[2];	 /* max recent measured bw sample */
-+	u32	inflight_latest; /* max delivered data in last round trip */
-+	u32	inflight_lo;	 /* lower bound of inflight data range */
-+	u32	inflight_hi;	 /* upper bound of inflight data range */
-+	u32	bw_probe_up_cnt; /* packets delivered per inflight_hi incr */
-+	u32	bw_probe_up_acks;  /* packets (S)ACKed since inflight_hi incr */
-+	u32	probe_wait_us;	 /* PROBE_DOWN until next clock-driven probe */
-+	u32	prior_rcv_nxt;	/* tp->rcv_nxt when CE state last changed */
-+	u32	ecn_eligible:1,	/* sender can use ECN (RTT, handshake)? */
-+		ecn_alpha:9,	/* EWMA delivered_ce/delivered; 0..256 */
-+		bw_probe_samples:1,    /* rate samples reflect bw probing? */
-+		prev_probe_too_high:1, /* did last PROBE_UP go too high? */
-+		stopped_risky_probe:1, /* last PROBE_UP stopped due to risk? */
-+		rounds_since_probe:8,  /* packet-timed rounds since probed bw */
-+		loss_round_start:1,    /* loss_round_delivered round trip? */
-+		loss_in_round:1,       /* loss marked in this round trip? */
-+		ecn_in_round:1,	       /* ECN marked in this round trip? */
-+		ack_phase:3,	       /* bbr_ack_phase: meaning of ACKs */
-+		loss_events_in_round:4,/* losses in STARTUP round */
-+		initialized:1;	       /* has bbr_init() been called? */
-+	u32	alpha_last_delivered;	 /* tp->delivered    at alpha update */
-+	u32	alpha_last_delivered_ce; /* tp->delivered_ce at alpha update */
-+
-+	u8	unused_4;		/* to preserve alignment */
-+	struct tcp_plb_state plb;
-+};
-+
-+struct bbr_context {
-+	u32 sample_bw;
-+};
-+
-+/* Window length of min_rtt filter (in sec): */
-+static const u32 bbr_min_rtt_win_sec = 10;
-+/* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode: */
-+static const u32 bbr_probe_rtt_mode_ms = 200;
-+/* Window length of probe_rtt_min_us filter (in ms), and consequently the
-+ * typical interval between PROBE_RTT mode entries. The default is 5000ms.
-+ * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC
-+ */
-+static const u32 bbr_probe_rtt_win_ms = 5000;
-+/* Proportion of cwnd to estimated BDP in PROBE_RTT, in units of BBR_UNIT: */
-+static const u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2;
-+
-+/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting
-+ * in bigger TSO bursts. We cut the RTT-based allowance in half
-+ * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance
-+ * is below 1500 bytes after 6 * ~500 usec = 3ms.
-+ */
-+static const u32 bbr_tso_rtt_shift = 9;
-+
-+/* Pace at ~1% below estimated bw, on average, to reduce queue at bottleneck.
-+ * In order to help drive the network toward lower queues and low latency while
-+ * maintaining high utilization, the average pacing rate aims to be slightly
-+ * lower than the estimated bandwidth. This is an important aspect of the
-+ * design.
-+ */
-+static const int bbr_pacing_margin_percent = 1;
-+
-+/* We use a startup_pacing_gain of 4*ln(2) because it's the smallest value
-+ * that will allow a smoothly increasing pacing rate that will double each RTT
-+ * and send the same number of packets per RTT that an un-paced, slow-starting
-+ * Reno or CUBIC flow would:
-+ */
-+static const int bbr_startup_pacing_gain = BBR_UNIT * 277 / 100 + 1;
-+/* The gain for deriving startup cwnd: */
-+static const int bbr_startup_cwnd_gain = BBR_UNIT * 2;
-+/* The pacing gain in BBR_DRAIN is calculated to typically drain
-+ * the queue created in BBR_STARTUP in a single round:
-+ */
-+static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885;
-+/* The gain for deriving steady-state cwnd tolerates delayed/stretched ACKs: */
-+static const int bbr_cwnd_gain  = BBR_UNIT * 2;
-+/* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw: */
-+static const int bbr_pacing_gain[] = {
-+	BBR_UNIT * 5 / 4,	/* UP: probe for more available bw */
-+	BBR_UNIT * 91 / 100,	/* DOWN: drain queue and/or yield bw */
-+	BBR_UNIT,		/* CRUISE: try to use pipe w/ some headroom */
-+	BBR_UNIT,		/* REFILL: refill pipe to estimated 100% */
-+};
-+enum bbr_pacing_gain_phase {
-+	BBR_BW_PROBE_UP		= 0,  /* push up inflight to probe for bw/vol */
-+	BBR_BW_PROBE_DOWN	= 1,  /* drain excess inflight from the queue */
-+	BBR_BW_PROBE_CRUISE	= 2,  /* use pipe, w/ headroom in queue/pipe */
-+	BBR_BW_PROBE_REFILL	= 3,  /* refill the pipe again to 100% */
-+};
-+
-+/* Try to keep at least this many packets in flight, if things go smoothly. For
-+ * smooth functioning, a sliding window protocol ACKing every other packet
-+ * needs at least 4 packets in flight:
-+ */
-+static const u32 bbr_cwnd_min_target = 4;
-+
-+/* To estimate if BBR_STARTUP or BBR_BW_PROBE_UP has filled pipe... */
-+/* If bw has increased significantly (1.25x), there may be more bw available: */
-+static const u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4;
-+/* But after 3 rounds w/o significant bw growth, estimate pipe is full: */
-+static const u32 bbr_full_bw_cnt = 3;
-+
-+/* Gain factor for adding extra_acked to target cwnd: */
-+static const int bbr_extra_acked_gain = BBR_UNIT;
-+/* Window length of extra_acked window. */
-+static const u32 bbr_extra_acked_win_rtts = 5;
-+/* Max allowed val for ack_epoch_acked, after which sampling epoch is reset */
-+static const u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20;
-+/* Time period for clamping cwnd increment due to ack aggregation */
-+static const u32 bbr_extra_acked_max_us = 100 * 1000;
-+
-+/* Flags to control BBR ECN-related behavior... */
-+
-+/* Ensure ACKs only ACK packets with consistent ECN CE status? */
-+static const bool bbr_precise_ece_ack = true;
-+
-+/* Max RTT (in usec) at which to use sender-side ECN logic.
-+ * Disabled when 0 (ECN allowed at any RTT).
-+ */
-+static const u32 bbr_ecn_max_rtt_us = 5000;
-+
-+/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE.
-+ * No loss response when 0.
-+ */
-+static const u32 bbr_beta = BBR_UNIT * 30 / 100;
-+
-+/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE (1/16 = 6.25%) */
-+static const u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16;
-+
-+/* The initial value for ecn_alpha; 1.0 allows a flow to respond quickly
-+ * to congestion if the bottleneck is congested when the flow starts up.
-+ */
-+static const u32 bbr_ecn_alpha_init = BBR_UNIT;
-+
-+/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE.
-+ * No ECN based bounding when 0.
-+ */
-+static const u32 bbr_ecn_factor = BBR_UNIT * 1 / 3;	 /* 1/3 = 33% */
-+
-+/* Estimate bw probing has gone too far if CE ratio exceeds this threshold.
-+ * Scaled by BBR_SCALE. Disabled when 0.
-+ */
-+static const u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2;  /* 1/2 = 50% */
-+
-+/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN
-+ * clears then make the first round's increment to inflight_hi the following
-+ * fraction of inflight_hi.
-+ */
-+static const u32 bbr_ecn_reprobe_gain = BBR_UNIT * 1 / 2;
-+
-+/* Estimate bw probing has gone too far if loss rate exceeds this level. */
-+static const u32 bbr_loss_thresh = BBR_UNIT * 2 / 100;  /* 2% loss */
-+
-+/* Slow down for a packet loss recovered by TLP? */
-+static const bool bbr_loss_probe_recovery = true;
-+
-+/* Exit STARTUP if number of loss marking events in a Recovery round is >= N,
-+ * and loss rate is higher than bbr_loss_thresh.
-+ * Disabled if 0.
-+ */
-+static const u32 bbr_full_loss_cnt = 6;
-+
-+/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh
-+ * meets this count.
-+ */
-+static const u32 bbr_full_ecn_cnt = 2;
-+
-+/* Fraction of unutilized headroom to try to leave in path upon high loss. */
-+static const u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100;
-+
-+/* How much do we increase cwnd_gain when probing for bandwidth in
-+ * BBR_BW_PROBE_UP? This specifies the increment in units of
-+ * BBR_UNIT/4. The default is 1, meaning 0.25.
-+ * The min value is 0 (meaning 0.0); max is 3 (meaning 0.75).
-+ */
-+static const u32 bbr_bw_probe_cwnd_gain = 1;
-+
-+/* Max number of packet-timed rounds to wait before probing for bandwidth.  If
-+ * we want to tolerate 1% random loss per round, and not have this cut our
-+ * inflight too much, we must probe for bw periodically on roughly this scale.
-+ * If low, limits Reno/CUBIC coexistence; if high, limits loss tolerance.
-+ * We aim to be fair with Reno/CUBIC up to a BDP of at least:
-+ *  BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets
-+ */
-+static const u32 bbr_bw_probe_max_rounds = 63;
-+
-+/* Max amount of randomness to inject in round counting for Reno-coexistence.
-+ */
-+static const u32 bbr_bw_probe_rand_rounds = 2;
-+
-+/* Use BBR-native probe time scale starting at this many usec.
-+ * We aim to be fair with Reno/CUBIC up to an inter-loss time epoch of at least:
-+ *  BDP*RTT = 25Mbps * .030sec /(1514bytes) * 0.030sec = 1.9 secs
-+ */
-+static const u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC;  /* 2 secs */
-+
-+/* Use BBR-native probes spread over this many usec: */
-+static const u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC;  /* 1 secs */
-+
-+/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */
-+static const bool bbr_fast_path = true;
-+
-+/* Use fast ack mode? */
-+static const bool bbr_fast_ack_mode = true;
-+
-+static u32 bbr_max_bw(const struct sock *sk);
-+static u32 bbr_bw(const struct sock *sk);
-+static void bbr_exit_probe_rtt(struct sock *sk);
-+static void bbr_reset_congestion_signals(struct sock *sk);
-+static void bbr_run_loss_probe_recovery(struct sock *sk);
-+
-+static void bbr_check_probe_rtt_done(struct sock *sk);
-+
-+/* This connection can use ECN if both endpoints have signaled ECN support in
-+ * the handshake and the per-route settings indicated this is a
-+ * shallow-threshold ECN environment, meaning both:
-+ *  (a) ECN CE marks indicate low-latency/shallow-threshold congestion, and
-+ *  (b) TCP endpoints provide precise ACKs that only ACK data segments
-+ *      with consistent ECN CE status
-+ */
-+static bool bbr_can_use_ecn(const struct sock *sk)
-+{
-+	return (tcp_sk(sk)->ecn_flags & TCP_ECN_OK) &&
-+	       (tcp_sk(sk)->ecn_flags & TCP_ECN_LOW);
-+}
-+
-+/* Do we estimate that STARTUP filled the pipe? */
-+static bool bbr_full_bw_reached(const struct sock *sk)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return bbr->full_bw_reached;
-+}
-+
-+/* Return the windowed max recent bandwidth sample, in pkts/uS << BW_SCALE. */
-+static u32 bbr_max_bw(const struct sock *sk)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return max(bbr->bw_hi[0], bbr->bw_hi[1]);
-+}
-+
-+/* Return the estimated bandwidth of the path, in pkts/uS << BW_SCALE. */
-+static u32 bbr_bw(const struct sock *sk)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return min(bbr_max_bw(sk), bbr->bw_lo);
-+}
-+
-+/* Return maximum extra acked in past k-2k round trips,
-+ * where k = bbr_extra_acked_win_rtts.
-+ */
-+static u16 bbr_extra_acked(const struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return max(bbr->extra_acked[0], bbr->extra_acked[1]);
-+}
-+
-+/* Return rate in bytes per second, optionally with a gain.
-+ * The order here is chosen carefully to avoid overflow of u64. This should
-+ * work for input rates of up to 2.9Tbit/sec and gain of 2.89x.
-+ */
-+static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain,
-+				  int margin)
-+{
-+	unsigned int mss = tcp_sk(sk)->mss_cache;
-+
-+	rate *= mss;
-+	rate *= gain;
-+	rate >>= BBR_SCALE;
-+	rate *= USEC_PER_SEC / 100 * (100 - margin);
-+	rate >>= BW_SCALE;
-+	rate = max(rate, 1ULL);
-+	return rate;
-+}
-+
-+static u64 bbr_bw_bytes_per_sec(struct sock *sk, u64 rate)
-+{
-+	return bbr_rate_bytes_per_sec(sk, rate, BBR_UNIT, 0);
-+}
-+
-+/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */
-+static unsigned long bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain)
-+{
-+	u64 rate = bw;
-+
-+	rate = bbr_rate_bytes_per_sec(sk, rate, gain,
-+				      bbr_pacing_margin_percent);
-+	rate = min_t(u64, rate, READ_ONCE(sk->sk_max_pacing_rate));
-+	return rate;
-+}
-+
-+/* Initialize pacing rate to: startup_pacing_gain * init_cwnd / RTT. */
-+static void bbr_init_pacing_rate_from_rtt(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u64 bw;
-+	u32 rtt_us;
-+
-+	if (tp->srtt_us) {		/* any RTT sample yet? */
-+		rtt_us = max(tp->srtt_us >> 3, 1U);
-+		bbr->has_seen_rtt = 1;
-+	} else {			 /* no RTT sample yet */
-+		rtt_us = USEC_PER_MSEC;	 /* use nominal default RTT */
-+	}
-+	bw = (u64)tcp_snd_cwnd(tp) * BW_UNIT;
-+	do_div(bw, rtt_us);
-+	WRITE_ONCE(sk->sk_pacing_rate,
-+		   bbr_bw_to_pacing_rate(sk, bw,
-+					 bbr_param(sk, startup_pacing_gain)));
-+}
-+
-+/* Pace using current bw estimate and a gain factor. */
-+static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	unsigned long rate = bbr_bw_to_pacing_rate(sk, bw, gain);
-+
-+	if (unlikely(!bbr->has_seen_rtt && tp->srtt_us))
-+		bbr_init_pacing_rate_from_rtt(sk);
-+	if (bbr_full_bw_reached(sk) || rate > READ_ONCE(sk->sk_pacing_rate))
-+		WRITE_ONCE(sk->sk_pacing_rate, rate);
-+}
-+
-+/* Return the number of segments BBR would like in a TSO/GSO skb, given a
-+ * particular max gso size as a constraint. TODO: make this simpler and more
-+ * consistent by switching bbr to just call tcp_tso_autosize().
-+ */
-+static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now,
-+				u32 gso_max_size)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 segs, r;
-+	u64 bytes;
-+
-+	/* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */
-+	bytes = READ_ONCE(sk->sk_pacing_rate) >> READ_ONCE(sk->sk_pacing_shift);
-+
-+	/* Budget a TSO/GSO burst size allowance based on min_rtt. For every
-+	 * K = 2^tso_rtt_shift microseconds of min_rtt, halve the burst.
-+	 * The min_rtt-based burst allowance is: 64 KBytes / 2^(min_rtt/K)
-+	 */
-+	if (bbr_param(sk, tso_rtt_shift)) {
-+		r = bbr->min_rtt_us >> bbr_param(sk, tso_rtt_shift);
-+		if (r < BITS_PER_TYPE(u32))   /* prevent undefined behavior */
-+			bytes += GSO_LEGACY_MAX_SIZE >> r;
-+	}
-+
-+	bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER);
-+	segs = max_t(u32, bytes / mss_now,
-+		     sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs);
-+	return segs;
-+}
-+
-+/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */
-+__bpf_kfunc static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now)
-+{
-+	return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size);
-+}
-+
-+/* Like bbr_tso_segs(), using mss_cache, ignoring driver's sk_gso_max_size. */
-+static u32 bbr_tso_segs_goal(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+
-+	return  bbr_tso_segs_generic(sk, tp->mss_cache, GSO_LEGACY_MAX_SIZE);
-+}
-+
-+/* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */
-+static void bbr_save_cwnd(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->prev_ca_state < TCP_CA_Recovery && bbr->mode != BBR_PROBE_RTT)
-+		bbr->prior_cwnd = tcp_snd_cwnd(tp);  /* this cwnd is good enough */
-+	else  /* loss recovery or BBR_PROBE_RTT have temporarily cut cwnd */
-+		bbr->prior_cwnd = max(bbr->prior_cwnd, tcp_snd_cwnd(tp));
-+}
-+
-+__bpf_kfunc static void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (event == CA_EVENT_TX_START) {
-+		if (!tp->app_limited)
-+			return;
-+		bbr->idle_restart = 1;
-+		bbr->ack_epoch_mstamp = tp->tcp_mstamp;
-+		bbr->ack_epoch_acked = 0;
-+		/* Avoid pointless buffer overflows: pace at est. bw if we don't
-+		 * need more speed (we're restarting from idle and app-limited).
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW)
-+			bbr_set_pacing_rate(sk, bbr_bw(sk), BBR_UNIT);
-+		else if (bbr->mode == BBR_PROBE_RTT)
-+			bbr_check_probe_rtt_done(sk);
-+	} else if ((event == CA_EVENT_ECN_IS_CE ||
-+		    event == CA_EVENT_ECN_NO_CE) &&
-+		   bbr_can_use_ecn(sk) &&
-+		   bbr_param(sk, precise_ece_ack)) {
-+		u32 state = bbr->ce_state;
-+		dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state);
-+		bbr->ce_state = state;
-+	} else if (event == CA_EVENT_TLP_RECOVERY &&
-+		   bbr_param(sk, loss_probe_recovery)) {
-+		bbr_run_loss_probe_recovery(sk);
-+	}
-+}
-+
-+/* Calculate bdp based on min RTT and the estimated bottleneck bandwidth:
-+ *
-+ * bdp = ceil(bw * min_rtt * gain)
-+ *
-+ * The key factor, gain, controls the amount of queue. While a small gain
-+ * builds a smaller queue, it becomes more vulnerable to noise in RTT
-+ * measurements (e.g., delayed ACKs or other ACK compression effects). This
-+ * noise may cause BBR to under-estimate the rate.
-+ */
-+static u32 bbr_bdp(struct sock *sk, u32 bw, int gain)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bdp;
-+	u64 w;
-+
-+	/* If we've never had a valid RTT sample, cap cwnd at the initial
-+	 * default. This should only happen when the connection is not using TCP
-+	 * timestamps and has retransmitted all of the SYN/SYNACK/data packets
-+	 * ACKed so far. In this case, an RTO can cut cwnd to 1, in which
-+	 * case we need to slow-start up toward something safe: initial cwnd.
-+	 */
-+	if (unlikely(bbr->min_rtt_us == ~0U))	 /* no valid RTT samples yet? */
-+		return bbr->init_cwnd;  /* be safe: cap at initial cwnd */
-+
-+	w = (u64)bw * bbr->min_rtt_us;
-+
-+	/* Apply a gain to the given value, remove the BW_SCALE shift, and
-+	 * round the value up to avoid a negative feedback loop.
-+	 */
-+	bdp = (((w * gain) >> BBR_SCALE) + BW_UNIT - 1) / BW_UNIT;
-+
-+	return bdp;
-+}
-+
-+/* To achieve full performance in high-speed paths, we budget enough cwnd to
-+ * fit full-sized skbs in-flight on both end hosts to fully utilize the path:
-+ *   - one skb in sending host Qdisc,
-+ *   - one skb in sending host TSO/GSO engine
-+ *   - one skb being received by receiver host LRO/GRO/delayed-ACK engine
-+ * Don't worry, at low rates this won't bloat cwnd because
-+ * in such cases tso_segs_goal is small. The minimum cwnd is 4 packets,
-+ * which allows 2 outstanding 2-packet sequences, to try to keep pipe
-+ * full even with ACK-every-other-packet delayed ACKs.
-+ */
-+static u32 bbr_quantization_budget(struct sock *sk, u32 cwnd)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 tso_segs_goal;
-+
-+	tso_segs_goal = 3 * bbr_tso_segs_goal(sk);
-+
-+	/* Allow enough full-sized skbs in flight to utilize end systems. */
-+	cwnd = max_t(u32, cwnd, tso_segs_goal);
-+	cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target));
-+	/* Ensure gain cycling gets inflight above BDP even for small BDPs. */
-+	if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP)
-+		cwnd += 2;
-+
-+	return cwnd;
-+}
-+
-+/* Find inflight based on min RTT and the estimated bottleneck bandwidth. */
-+static u32 bbr_inflight(struct sock *sk, u32 bw, int gain)
-+{
-+	u32 inflight;
-+
-+	inflight = bbr_bdp(sk, bw, gain);
-+	inflight = bbr_quantization_budget(sk, inflight);
-+
-+	return inflight;
-+}
-+
-+/* With pacing at lower layers, there's often less data "in the network" than
-+ * "in flight". With TSQ and departure time pacing at lower layers (e.g. fq),
-+ * we often have several skbs queued in the pacing layer with a pre-scheduled
-+ * earliest departure time (EDT). BBR adapts its pacing rate based on the
-+ * inflight level that it estimates has already been "baked in" by previous
-+ * departure time decisions. We calculate a rough estimate of the number of our
-+ * packets that might be in the network at the earliest departure time for the
-+ * next skb scheduled:
-+ *   in_network_at_edt = inflight_at_edt - (EDT - now) * bw
-+ * If we're increasing inflight, then we want to know if the transmit of the
-+ * EDT skb will push inflight above the target, so inflight_at_edt includes
-+ * bbr_tso_segs_goal() from the skb departing at EDT. If decreasing inflight,
-+ * then estimate if inflight will sink too low just before the EDT transmit.
-+ */
-+static u32 bbr_packets_in_net_at_edt(struct sock *sk, u32 inflight_now)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u64 now_ns, edt_ns, interval_us;
-+	u32 interval_delivered, inflight_at_edt;
-+
-+	now_ns = tp->tcp_clock_cache;
-+	edt_ns = max(tp->tcp_wstamp_ns, now_ns);
-+	interval_us = div_u64(edt_ns - now_ns, NSEC_PER_USEC);
-+	interval_delivered = (u64)bbr_bw(sk) * interval_us >> BW_SCALE;
-+	inflight_at_edt = inflight_now;
-+	if (bbr->pacing_gain > BBR_UNIT)              /* increasing inflight */
-+		inflight_at_edt += bbr_tso_segs_goal(sk);  /* include EDT skb */
-+	if (interval_delivered >= inflight_at_edt)
-+		return 0;
-+	return inflight_at_edt - interval_delivered;
-+}
-+
-+/* Find the cwnd increment based on estimate of ack aggregation */
-+static u32 bbr_ack_aggregation_cwnd(struct sock *sk)
-+{
-+	u32 max_aggr_cwnd, aggr_cwnd = 0;
-+
-+	if (bbr_param(sk, extra_acked_gain)) {
-+		max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us)
-+				/ BW_UNIT;
-+		aggr_cwnd = (bbr_param(sk, extra_acked_gain) * bbr_extra_acked(sk))
-+			     >> BBR_SCALE;
-+		aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd);
-+	}
-+
-+	return aggr_cwnd;
-+}
-+
-+/* Returns the cwnd for PROBE_RTT mode. */
-+static u32 bbr_probe_rtt_cwnd(struct sock *sk)
-+{
-+	return max_t(u32, bbr_param(sk, cwnd_min_target),
-+		     bbr_bdp(sk, bbr_bw(sk), bbr_param(sk, probe_rtt_cwnd_gain)));
-+}
-+
-+/* Slow-start up toward target cwnd (if bw estimate is growing, or packet loss
-+ * has drawn us down below target), or snap down to target if we're above it.
-+ */
-+static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs,
-+			 u32 acked, u32 bw, int gain, u32 cwnd,
-+			 struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 target_cwnd = 0;
-+
-+	if (!acked)
-+		goto done;  /* no packet fully ACKed; just apply caps */
-+
-+	target_cwnd = bbr_bdp(sk, bw, gain);
-+
-+	/* Increment the cwnd to account for excess ACKed data that seems
-+	 * due to aggregation (of data and/or ACKs) visible in the ACK stream.
-+	 */
-+	target_cwnd += bbr_ack_aggregation_cwnd(sk);
-+	target_cwnd = bbr_quantization_budget(sk, target_cwnd);
-+
-+	/* Update cwnd and enable fast path if cwnd reaches target_cwnd. */
-+	bbr->try_fast_path = 0;
-+	if (bbr_full_bw_reached(sk)) { /* only cut cwnd if we filled the pipe */
-+		cwnd += acked;
-+		if (cwnd >= target_cwnd) {
-+			cwnd = target_cwnd;
-+			bbr->try_fast_path = 1;
-+		}
-+	} else if (cwnd < target_cwnd || cwnd  < 2 * bbr->init_cwnd) {
-+		cwnd += acked;
-+	} else {
-+		bbr->try_fast_path = 1;
-+	}
-+
-+	cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target));
-+done:
-+	tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp));  /* global cap */
-+	if (bbr->mode == BBR_PROBE_RTT)  /* drain queue, refresh min_rtt */
-+		tcp_snd_cwnd_set(tp, min_t(u32, tcp_snd_cwnd(tp),
-+					   bbr_probe_rtt_cwnd(sk)));
-+}
-+
-+static void bbr_reset_startup_mode(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->mode = BBR_STARTUP;
-+}
-+
-+/* See if we have reached next round trip. Upon start of the new round,
-+ * returns packets delivered since previous round start plus this ACK.
-+ */
-+static u32 bbr_update_round_start(struct sock *sk,
-+		const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 round_delivered = 0;
-+
-+	bbr->round_start = 0;
-+
-+	/* See if we've reached the next RTT */
-+	if (rs->interval_us > 0 &&
-+	    !before(rs->prior_delivered, bbr->next_rtt_delivered)) {
-+		round_delivered = tp->delivered - bbr->next_rtt_delivered;
-+		bbr->next_rtt_delivered = tp->delivered;
-+		bbr->round_start = 1;
-+	}
-+	return round_delivered;
-+}
-+
-+/* Calculate the bandwidth based on how fast packets are delivered */
-+static void bbr_calculate_bw_sample(struct sock *sk,
-+			const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	u64 bw = 0;
-+
-+	/* Divide delivered by the interval to find a (lower bound) bottleneck
-+	 * bandwidth sample. Delivered is in packets and interval_us in uS and
-+	 * ratio will be <<1 for most connections. So delivered is first scaled.
-+	 * Round up to allow growth at low rates, even with integer division.
-+	 */
-+	if (rs->interval_us > 0) {
-+		if (WARN_ONCE(rs->delivered < 0,
-+			      "negative delivered: %d interval_us: %ld\n",
-+			      rs->delivered, rs->interval_us))
-+			return;
-+
-+		bw = DIV_ROUND_UP_ULL((u64)rs->delivered * BW_UNIT, rs->interval_us);
-+	}
-+
-+	ctx->sample_bw = bw;
-+}
-+
-+/* Estimates the windowed max degree of ack aggregation.
-+ * This is used to provision extra in-flight data to keep sending during
-+ * inter-ACK silences.
-+ *
-+ * Degree of ack aggregation is estimated as extra data acked beyond expected.
-+ *
-+ * max_extra_acked = "maximum recent excess data ACKed beyond max_bw * interval"
-+ * cwnd += max_extra_acked
-+ *
-+ * Max extra_acked is clamped by cwnd and bw * bbr_extra_acked_max_us (100 ms).
-+ * Max filter is an approximate sliding window of 5-10 (packet timed) round
-+ * trips for non-startup phase, and 1-2 round trips for startup.
-+ */
-+static void bbr_update_ack_aggregation(struct sock *sk,
-+				       const struct rate_sample *rs)
-+{
-+	u32 epoch_us, expected_acked, extra_acked;
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	u32 extra_acked_win_rtts_thresh = bbr_param(sk, extra_acked_win_rtts);
-+
-+	if (!bbr_param(sk, extra_acked_gain) || rs->acked_sacked <= 0 ||
-+	    rs->delivered < 0 || rs->interval_us <= 0)
-+		return;
-+
-+	if (bbr->round_start) {
-+		bbr->extra_acked_win_rtts = min(0x1F,
-+						bbr->extra_acked_win_rtts + 1);
-+		if (!bbr_full_bw_reached(sk))
-+			extra_acked_win_rtts_thresh = 1;
-+		if (bbr->extra_acked_win_rtts >=
-+		    extra_acked_win_rtts_thresh) {
-+			bbr->extra_acked_win_rtts = 0;
-+			bbr->extra_acked_win_idx = bbr->extra_acked_win_idx ?
-+						   0 : 1;
-+			bbr->extra_acked[bbr->extra_acked_win_idx] = 0;
-+		}
-+	}
-+
-+	/* Compute how many packets we expected to be delivered over epoch. */
-+	epoch_us = tcp_stamp_us_delta(tp->delivered_mstamp,
-+				      bbr->ack_epoch_mstamp);
-+	expected_acked = ((u64)bbr_bw(sk) * epoch_us) / BW_UNIT;
-+
-+	/* Reset the aggregation epoch if ACK rate is below expected rate or
-+	 * significantly large no. of ack received since epoch (potentially
-+	 * quite old epoch).
-+	 */
-+	if (bbr->ack_epoch_acked <= expected_acked ||
-+	    (bbr->ack_epoch_acked + rs->acked_sacked >=
-+	     bbr_ack_epoch_acked_reset_thresh)) {
-+		bbr->ack_epoch_acked = 0;
-+		bbr->ack_epoch_mstamp = tp->delivered_mstamp;
-+		expected_acked = 0;
-+	}
-+
-+	/* Compute excess data delivered, beyond what was expected. */
-+	bbr->ack_epoch_acked = min_t(u32, 0xFFFFF,
-+				     bbr->ack_epoch_acked + rs->acked_sacked);
-+	extra_acked = bbr->ack_epoch_acked - expected_acked;
-+	extra_acked = min(extra_acked, tcp_snd_cwnd(tp));
-+	if (extra_acked > bbr->extra_acked[bbr->extra_acked_win_idx])
-+		bbr->extra_acked[bbr->extra_acked_win_idx] = extra_acked;
-+}
-+
-+static void bbr_check_probe_rtt_done(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (!(bbr->probe_rtt_done_stamp &&
-+	      after(tcp_jiffies32, bbr->probe_rtt_done_stamp)))
-+		return;
-+
-+	bbr->probe_rtt_min_stamp = tcp_jiffies32; /* schedule next PROBE_RTT */
-+	tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd));
-+	bbr_exit_probe_rtt(sk);
-+}
-+
-+/* The goal of PROBE_RTT mode is to have BBR flows cooperatively and
-+ * periodically drain the bottleneck queue, to converge to measure the true
-+ * min_rtt (unloaded propagation delay). This allows the flows to keep queues
-+ * small (reducing queuing delay and packet loss) and achieve fairness among
-+ * BBR flows.
-+ *
-+ * The min_rtt filter window is 10 seconds. When the min_rtt estimate expires,
-+ * we enter PROBE_RTT mode and cap the cwnd at bbr_cwnd_min_target=4 packets.
-+ * After at least bbr_probe_rtt_mode_ms=200ms and at least one packet-timed
-+ * round trip elapsed with that flight size <= 4, we leave PROBE_RTT mode and
-+ * re-enter the previous mode. BBR uses 200ms to approximately bound the
-+ * performance penalty of PROBE_RTT's cwnd capping to roughly 2% (200ms/10s).
-+ *
-+ * Note that flows need only pay 2% if they are busy sending over the last 10
-+ * seconds. Interactive applications (e.g., Web, RPCs, video chunks) often have
-+ * natural silences or low-rate periods within 10 seconds where the rate is low
-+ * enough for long enough to drain its queue in the bottleneck. We pick up
-+ * these min RTT measurements opportunistically with our min_rtt filter. :-)
-+ */
-+static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	bool probe_rtt_expired, min_rtt_expired;
-+	u32 expire;
-+
-+	/* Track min RTT in probe_rtt_win_ms to time next PROBE_RTT state. */
-+	expire = bbr->probe_rtt_min_stamp +
-+		 msecs_to_jiffies(bbr_param(sk, probe_rtt_win_ms));
-+	probe_rtt_expired = after(tcp_jiffies32, expire);
-+	if (rs->rtt_us >= 0 &&
-+	    (rs->rtt_us < bbr->probe_rtt_min_us ||
-+	     (probe_rtt_expired && !rs->is_ack_delayed))) {
-+		bbr->probe_rtt_min_us = rs->rtt_us;
-+		bbr->probe_rtt_min_stamp = tcp_jiffies32;
-+	}
-+	/* Track min RTT seen in the min_rtt_win_sec filter window: */
-+	expire = bbr->min_rtt_stamp + bbr_param(sk, min_rtt_win_sec) * HZ;
-+	min_rtt_expired = after(tcp_jiffies32, expire);
-+	if (bbr->probe_rtt_min_us <= bbr->min_rtt_us ||
-+	    min_rtt_expired) {
-+		bbr->min_rtt_us = bbr->probe_rtt_min_us;
-+		bbr->min_rtt_stamp = bbr->probe_rtt_min_stamp;
-+	}
-+
-+	if (bbr_param(sk, probe_rtt_mode_ms) > 0 && probe_rtt_expired &&
-+	    !bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) {
-+		bbr->mode = BBR_PROBE_RTT;  /* dip, drain queue */
-+		bbr_save_cwnd(sk);  /* note cwnd so we can restore it */
-+		bbr->probe_rtt_done_stamp = 0;
-+		bbr->ack_phase = BBR_ACKS_PROBE_STOPPING;
-+		bbr->next_rtt_delivered = tp->delivered;
-+	}
-+
-+	if (bbr->mode == BBR_PROBE_RTT) {
-+		/* Ignore low rate samples during this mode. */
-+		tp->app_limited =
-+			(tp->delivered + tcp_packets_in_flight(tp)) ? : 1;
-+		/* Maintain min packets in flight for max(200 ms, 1 round). */
-+		if (!bbr->probe_rtt_done_stamp &&
-+		    tcp_packets_in_flight(tp) <= bbr_probe_rtt_cwnd(sk)) {
-+			bbr->probe_rtt_done_stamp = tcp_jiffies32 +
-+				msecs_to_jiffies(bbr_param(sk, probe_rtt_mode_ms));
-+			bbr->probe_rtt_round_done = 0;
-+			bbr->next_rtt_delivered = tp->delivered;
-+		} else if (bbr->probe_rtt_done_stamp) {
-+			if (bbr->round_start)
-+				bbr->probe_rtt_round_done = 1;
-+			if (bbr->probe_rtt_round_done)
-+				bbr_check_probe_rtt_done(sk);
-+		}
-+	}
-+	/* Restart after idle ends only once we process a new S/ACK for data */
-+	if (rs->delivered > 0)
-+		bbr->idle_restart = 0;
-+}
-+
-+static void bbr_update_gains(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	switch (bbr->mode) {
-+	case BBR_STARTUP:
-+		bbr->pacing_gain = bbr_param(sk, startup_pacing_gain);
-+		bbr->cwnd_gain	 = bbr_param(sk, startup_cwnd_gain);
-+		break;
-+	case BBR_DRAIN:
-+		bbr->pacing_gain = bbr_param(sk, drain_gain);  /* slow, to drain */
-+		bbr->cwnd_gain	 = bbr_param(sk, startup_cwnd_gain);  /* keep cwnd */
-+		break;
-+	case BBR_PROBE_BW:
-+		bbr->pacing_gain = bbr_pacing_gain[bbr->cycle_idx];
-+		bbr->cwnd_gain	 = bbr_param(sk, cwnd_gain);
-+		if (bbr_param(sk, bw_probe_cwnd_gain) &&
-+		    bbr->cycle_idx == BBR_BW_PROBE_UP)
-+			bbr->cwnd_gain +=
-+				BBR_UNIT * bbr_param(sk, bw_probe_cwnd_gain) / 4;
-+		break;
-+	case BBR_PROBE_RTT:
-+		bbr->pacing_gain = BBR_UNIT;
-+		bbr->cwnd_gain	 = BBR_UNIT;
-+		break;
-+	default:
-+		WARN_ONCE(1, "BBR bad mode: %u\n", bbr->mode);
-+		break;
-+	}
-+}
-+
-+__bpf_kfunc static u32 bbr_sndbuf_expand(struct sock *sk)
-+{
-+	/* Provision 3 * cwnd since BBR may slow-start even during recovery. */
-+	return 3;
-+}
-+
-+/* Incorporate a new bw sample into the current window of our max filter. */
-+static void bbr_take_max_bw_sample(struct sock *sk, u32 bw)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->bw_hi[1] = max(bw, bbr->bw_hi[1]);
-+}
-+
-+/* Keep max of last 1-2 cycles. Each PROBE_BW cycle, flip filter window. */
-+static void bbr_advance_max_bw_filter(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (!bbr->bw_hi[1])
-+		return;  /* no samples in this window; remember old window */
-+	bbr->bw_hi[0] = bbr->bw_hi[1];
-+	bbr->bw_hi[1] = 0;
-+}
-+
-+/* Reset the estimator for reaching full bandwidth based on bw plateau. */
-+static void bbr_reset_full_bw(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->full_bw = 0;
-+	bbr->full_bw_cnt = 0;
-+	bbr->full_bw_now = 0;
-+}
-+
-+/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */
-+static u32 bbr_target_inflight(struct sock *sk)
-+{
-+	u32 bdp = bbr_inflight(sk, bbr_bw(sk), BBR_UNIT);
-+
-+	return min(bdp, tcp_sk(sk)->snd_cwnd);
-+}
-+
-+static bool bbr_is_probing_bandwidth(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return (bbr->mode == BBR_STARTUP) ||
-+		(bbr->mode == BBR_PROBE_BW &&
-+		 (bbr->cycle_idx == BBR_BW_PROBE_REFILL ||
-+		  bbr->cycle_idx == BBR_BW_PROBE_UP));
-+}
-+
-+/* Has the given amount of time elapsed since we marked the phase start? */
-+static bool bbr_has_elapsed_in_phase(const struct sock *sk, u32 interval_us)
-+{
-+	const struct tcp_sock *tp = tcp_sk(sk);
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return tcp_stamp_us_delta(tp->tcp_mstamp,
-+				  bbr->cycle_mstamp + interval_us) > 0;
-+}
-+
-+static void bbr_handle_queue_too_high_in_startup(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bdp;  /* estimated BDP in packets, with quantization budget */
-+
-+	bbr->full_bw_reached = 1;
-+
-+	bdp = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+	bbr->inflight_hi = max(bdp, bbr->inflight_latest);
-+}
-+
-+/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */
-+static void bbr_check_ecn_too_high_in_startup(struct sock *sk, u32 ce_ratio)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr_full_bw_reached(sk) || !bbr->ecn_eligible ||
-+	    !bbr_param(sk, full_ecn_cnt) || !bbr_param(sk, ecn_thresh))
-+		return;
-+
-+	if (ce_ratio >= bbr_param(sk, ecn_thresh))
-+		bbr->startup_ecn_rounds++;
-+	else
-+		bbr->startup_ecn_rounds = 0;
-+
-+	if (bbr->startup_ecn_rounds >= bbr_param(sk, full_ecn_cnt)) {
-+		bbr_handle_queue_too_high_in_startup(sk);
-+		return;
-+	}
-+}
-+
-+/* Updates ecn_alpha and returns ce_ratio. -1 if not available. */
-+static int bbr_update_ecn_alpha(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct net *net = sock_net(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	s32 delivered, delivered_ce;
-+	u64 alpha, ce_ratio;
-+	u32 gain;
-+	bool want_ecn_alpha;
-+
-+	/* See if we should use ECN sender logic for this connection. */
-+	if (!bbr->ecn_eligible && bbr_can_use_ecn(sk) &&
-+	    !!bbr_param(sk, ecn_factor) &&
-+	    (bbr->min_rtt_us <= bbr_ecn_max_rtt_us ||
-+	     !bbr_ecn_max_rtt_us))
-+		bbr->ecn_eligible = 1;
-+
-+	/* Skip updating alpha only if not ECN-eligible and PLB is disabled. */
-+	want_ecn_alpha = (bbr->ecn_eligible ||
-+			  (bbr_can_use_ecn(sk) &&
-+			   READ_ONCE(net->ipv4.sysctl_tcp_plb_enabled)));
-+	if (!want_ecn_alpha)
-+		return -1;
-+
-+	delivered = tp->delivered - bbr->alpha_last_delivered;
-+	delivered_ce = tp->delivered_ce - bbr->alpha_last_delivered_ce;
-+
-+	if (delivered == 0 ||		/* avoid divide by zero */
-+	    WARN_ON_ONCE(delivered < 0 || delivered_ce < 0))  /* backwards? */
-+		return -1;
-+
-+	BUILD_BUG_ON(BBR_SCALE != TCP_PLB_SCALE);
-+	ce_ratio = (u64)delivered_ce << BBR_SCALE;
-+	do_div(ce_ratio, delivered);
-+
-+	gain = bbr_param(sk, ecn_alpha_gain);
-+	alpha = ((BBR_UNIT - gain) * bbr->ecn_alpha) >> BBR_SCALE;
-+	alpha += (gain * ce_ratio) >> BBR_SCALE;
-+	bbr->ecn_alpha = min_t(u32, alpha, BBR_UNIT);
-+
-+	bbr->alpha_last_delivered = tp->delivered;
-+	bbr->alpha_last_delivered_ce = tp->delivered_ce;
-+
-+	bbr_check_ecn_too_high_in_startup(sk, ce_ratio);
-+	return (int)ce_ratio;
-+}
-+
-+/* Protective Load Balancing (PLB). PLB rehashes outgoing data (to a new IPv6
-+ * flow label) if it encounters sustained congestion in the form of ECN marks.
-+ */
-+static void bbr_plb(struct sock *sk, const struct rate_sample *rs, int ce_ratio)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->round_start && ce_ratio >= 0)
-+		tcp_plb_update_state(sk, &bbr->plb, ce_ratio);
-+
-+	tcp_plb_check_rehash(sk, &bbr->plb);
-+}
-+
-+/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */
-+static void bbr_raise_inflight_hi_slope(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 growth_this_round, cnt;
-+
-+	/* Calculate "slope": packets S/Acked per inflight_hi increment. */
-+	growth_this_round = 1 << bbr->bw_probe_up_rounds;
-+	bbr->bw_probe_up_rounds = min(bbr->bw_probe_up_rounds + 1, 30);
-+	cnt = tcp_snd_cwnd(tp) / growth_this_round;
-+	cnt = max(cnt, 1U);
-+	bbr->bw_probe_up_cnt = cnt;
-+}
-+
-+/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */
-+static void bbr_probe_inflight_hi_upward(struct sock *sk,
-+					  const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 delta;
-+
-+	if (!tp->is_cwnd_limited || tcp_snd_cwnd(tp) < bbr->inflight_hi)
-+		return;  /* not fully using inflight_hi, so don't grow it */
-+
-+	/* For each bw_probe_up_cnt packets ACKed, increase inflight_hi by 1. */
-+	bbr->bw_probe_up_acks += rs->acked_sacked;
-+	if (bbr->bw_probe_up_acks >=  bbr->bw_probe_up_cnt) {
-+		delta = bbr->bw_probe_up_acks / bbr->bw_probe_up_cnt;
-+		bbr->bw_probe_up_acks -= delta * bbr->bw_probe_up_cnt;
-+		bbr->inflight_hi += delta;
-+		bbr->try_fast_path = 0;  /* Need to update cwnd */
-+	}
-+
-+	if (bbr->round_start)
-+		bbr_raise_inflight_hi_slope(sk);
-+}
-+
-+/* Does loss/ECN rate for this sample say inflight is "too high"?
-+ * This is used by both the bbr_check_loss_too_high_in_startup() function,
-+ * and in PROBE_UP.
-+ */
-+static bool bbr_is_inflight_too_high(const struct sock *sk,
-+				      const struct rate_sample *rs)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+	u32 loss_thresh, ecn_thresh;
-+
-+	if (rs->lost > 0 && rs->tx_in_flight) {
-+		loss_thresh = (u64)rs->tx_in_flight * bbr_param(sk, loss_thresh) >>
-+				BBR_SCALE;
-+		if (rs->lost > loss_thresh) {
-+			return true;
-+		}
-+	}
-+
-+	if (rs->delivered_ce > 0 && rs->delivered > 0 &&
-+	    bbr->ecn_eligible && !!bbr_param(sk, ecn_thresh)) {
-+		ecn_thresh = (u64)rs->delivered * bbr_param(sk, ecn_thresh) >>
-+				BBR_SCALE;
-+		if (rs->delivered_ce > ecn_thresh) {
-+			return true;
-+		}
-+	}
-+
-+	return false;
-+}
-+
-+/* Calculate the tx_in_flight level that corresponded to excessive loss.
-+ * We find "lost_prefix" segs of the skb where loss rate went too high,
-+ * by solving for "lost_prefix" in the following equation:
-+ *   lost                     /  inflight                     >= loss_thresh
-+ *  (lost_prev + lost_prefix) / (inflight_prev + lost_prefix) >= loss_thresh
-+ * Then we take that equation, convert it to fixed point, and
-+ * round up to the nearest packet.
-+ */
-+static u32 bbr_inflight_hi_from_lost_skb(const struct sock *sk,
-+					  const struct rate_sample *rs,
-+					  const struct sk_buff *skb)
-+{
-+	const struct tcp_sock *tp = tcp_sk(sk);
-+	u32 loss_thresh  = bbr_param(sk, loss_thresh);
-+	u32 pcount, divisor, inflight_hi;
-+	s32 inflight_prev, lost_prev;
-+	u64 loss_budget, lost_prefix;
-+
-+	pcount = tcp_skb_pcount(skb);
-+
-+	/* How much data was in flight before this skb? */
-+	inflight_prev = rs->tx_in_flight - pcount;
-+	if (inflight_prev < 0) {
-+		WARN_ONCE(tcp_skb_tx_in_flight_is_suspicious(
-+				  pcount,
-+				  TCP_SKB_CB(skb)->sacked,
-+				  rs->tx_in_flight),
-+			  "tx_in_flight: %u pcount: %u reneg: %u",
-+			  rs->tx_in_flight, pcount, tcp_sk(sk)->is_sack_reneg);
-+		return ~0U;
-+	}
-+
-+	/* How much inflight data was marked lost before this skb? */
-+	lost_prev = rs->lost - pcount;
-+	if (WARN_ONCE(lost_prev < 0,
-+		      "cwnd: %u ca: %d out: %u lost: %u pif: %u "
-+		      "tx_in_flight: %u tx.lost: %u tp->lost: %u rs->lost: %d "
-+		      "lost_prev: %d pcount: %d seq: %u end_seq: %u reneg: %u",
-+		      tcp_snd_cwnd(tp), inet_csk(sk)->icsk_ca_state,
-+		      tp->packets_out, tp->lost_out, tcp_packets_in_flight(tp),
-+		      rs->tx_in_flight, TCP_SKB_CB(skb)->tx.lost, tp->lost,
-+		      rs->lost, lost_prev, pcount,
-+		      TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
-+		      tp->is_sack_reneg))
-+		return ~0U;
-+
-+	/* At what prefix of this lost skb did losss rate exceed loss_thresh? */
-+	loss_budget = (u64)inflight_prev * loss_thresh + BBR_UNIT - 1;
-+	loss_budget >>= BBR_SCALE;
-+	if (lost_prev >= loss_budget) {
-+		lost_prefix = 0;   /* previous losses crossed loss_thresh */
-+	} else {
-+		lost_prefix = loss_budget - lost_prev;
-+		lost_prefix <<= BBR_SCALE;
-+		divisor = BBR_UNIT - loss_thresh;
-+		if (WARN_ON_ONCE(!divisor))  /* loss_thresh is 8 bits */
-+			return ~0U;
-+		do_div(lost_prefix, divisor);
-+	}
-+
-+	inflight_hi = inflight_prev + lost_prefix;
-+	return inflight_hi;
-+}
-+
-+/* If loss/ECN rates during probing indicated we may have overfilled a
-+ * buffer, return an operating point that tries to leave unutilized headroom in
-+ * the path for other flows, for fairness convergence and lower RTTs and loss.
-+ */
-+static u32 bbr_inflight_with_headroom(const struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 headroom, headroom_fraction;
-+
-+	if (bbr->inflight_hi == ~0U)
-+		return ~0U;
-+
-+	headroom_fraction = bbr_param(sk, inflight_headroom);
-+	headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE;
-+	headroom = max(headroom, 1U);
-+	return max_t(s32, bbr->inflight_hi - headroom,
-+		     bbr_param(sk, cwnd_min_target));
-+}
-+
-+/* Bound cwnd to a sensible level, based on our current probing state
-+ * machine phase and model of a good inflight level (inflight_lo, inflight_hi).
-+ */
-+static void bbr_bound_cwnd_for_inflight_model(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 cap;
-+
-+	/* tcp_rcv_synsent_state_process() currently calls tcp_ack()
-+	 * and thus cong_control() without first initializing us(!).
-+	 */
-+	if (!bbr->initialized)
-+		return;
-+
-+	cap = ~0U;
-+	if (bbr->mode == BBR_PROBE_BW &&
-+	    bbr->cycle_idx != BBR_BW_PROBE_CRUISE) {
-+		/* Probe to see if more packets fit in the path. */
-+		cap = bbr->inflight_hi;
-+	} else {
-+		if (bbr->mode == BBR_PROBE_RTT ||
-+		    (bbr->mode == BBR_PROBE_BW &&
-+		     bbr->cycle_idx == BBR_BW_PROBE_CRUISE))
-+			cap = bbr_inflight_with_headroom(sk);
-+	}
-+	/* Adapt to any loss/ECN since our last bw probe. */
-+	cap = min(cap, bbr->inflight_lo);
-+
-+	cap = max_t(u32, cap, bbr_param(sk, cwnd_min_target));
-+	tcp_snd_cwnd_set(tp, min(cap, tcp_snd_cwnd(tp)));
-+}
-+
-+/* How should we multiplicatively cut bw or inflight limits based on ECN? */
-+static u32 bbr_ecn_cut(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return BBR_UNIT -
-+		((bbr->ecn_alpha * bbr_param(sk, ecn_factor)) >> BBR_SCALE);
-+}
-+
-+/* Init lower bounds if have not inited yet. */
-+static void bbr_init_lower_bounds(struct sock *sk, bool init_bw)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (init_bw && bbr->bw_lo == ~0U)
-+		bbr->bw_lo = bbr_max_bw(sk);
-+	if (bbr->inflight_lo == ~0U)
-+		bbr->inflight_lo = tcp_snd_cwnd(tp);
-+}
-+
-+/* Reduce bw and inflight to (1 - beta). */
-+static void bbr_loss_lower_bounds(struct sock *sk, u32 *bw, u32 *inflight)
-+{
-+	struct bbr* bbr = inet_csk_ca(sk);
-+	u32 loss_cut = BBR_UNIT - bbr_param(sk, beta);
-+
-+	*bw = max_t(u32, bbr->bw_latest,
-+		    (u64)bbr->bw_lo * loss_cut >> BBR_SCALE);
-+	*inflight = max_t(u32, bbr->inflight_latest,
-+			  (u64)bbr->inflight_lo * loss_cut >> BBR_SCALE);
-+}
-+
-+/* Reduce inflight to (1 - alpha*ecn_factor). */
-+static void bbr_ecn_lower_bounds(struct sock *sk, u32 *inflight)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 ecn_cut = bbr_ecn_cut(sk);
-+
-+	*inflight = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE;
-+}
-+
-+/* Estimate a short-term lower bound on the capacity available now, based
-+ * on measurements of the current delivery process and recent history. When we
-+ * are seeing loss/ECN at times when we are not probing bw, then conservatively
-+ * move toward flow balance by multiplicatively cutting our short-term
-+ * estimated safe rate and volume of data (bw_lo and inflight_lo). We use a
-+ * multiplicative decrease in order to converge to a lower capacity in time
-+ * logarithmic in the magnitude of the decrease.
-+ *
-+ * However, we do not cut our short-term estimates lower than the current rate
-+ * and volume of delivered data from this round trip, since from the current
-+ * delivery process we can estimate the measured capacity available now.
-+ *
-+ * Anything faster than that approach would knowingly risk high loss, which can
-+ * cause low bw for Reno/CUBIC and high loss recovery latency for
-+ * request/response flows using any congestion control.
-+ */
-+static void bbr_adapt_lower_bounds(struct sock *sk,
-+				    const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 ecn_inflight_lo = ~0U;
-+
-+	/* We only use lower-bound estimates when not probing bw.
-+	 * When probing we need to push inflight higher to probe bw.
-+	 */
-+	if (bbr_is_probing_bandwidth(sk))
-+		return;
-+
-+	/* ECN response. */
-+	if (bbr->ecn_in_round && !!bbr_param(sk, ecn_factor)) {
-+		bbr_init_lower_bounds(sk, false);
-+		bbr_ecn_lower_bounds(sk, &ecn_inflight_lo);
-+	}
-+
-+	/* Loss response. */
-+	if (bbr->loss_in_round) {
-+		bbr_init_lower_bounds(sk, true);
-+		bbr_loss_lower_bounds(sk, &bbr->bw_lo, &bbr->inflight_lo);
-+	}
-+
-+	/* Adjust to the lower of the levels implied by loss/ECN. */
-+	bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo);
-+	bbr->bw_lo = max(1U, bbr->bw_lo);
-+}
-+
-+/* Reset any short-term lower-bound adaptation to congestion, so that we can
-+ * push our inflight up.
-+ */
-+static void bbr_reset_lower_bounds(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->bw_lo = ~0U;
-+	bbr->inflight_lo = ~0U;
-+}
-+
-+/* After bw probing (STARTUP/PROBE_UP), reset signals before entering a state
-+ * machine phase where we adapt our lower bound based on congestion signals.
-+ */
-+static void bbr_reset_congestion_signals(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->loss_in_round = 0;
-+	bbr->ecn_in_round = 0;
-+	bbr->loss_in_cycle = 0;
-+	bbr->ecn_in_cycle = 0;
-+	bbr->bw_latest = 0;
-+	bbr->inflight_latest = 0;
-+}
-+
-+static void bbr_exit_loss_recovery(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd));
-+	bbr->try_fast_path = 0; /* bound cwnd using latest model */
-+}
-+
-+/* Update rate and volume of delivered data from latest round trip. */
-+static void bbr_update_latest_delivery_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->loss_round_start = 0;
-+	if (rs->interval_us <= 0 || !rs->acked_sacked)
-+		return; /* Not a valid observation */
-+
-+	bbr->bw_latest       = max_t(u32, bbr->bw_latest,       ctx->sample_bw);
-+	bbr->inflight_latest = max_t(u32, bbr->inflight_latest, rs->delivered);
-+
-+	if (!before(rs->prior_delivered, bbr->loss_round_delivered)) {
-+		bbr->loss_round_delivered = tp->delivered;
-+		bbr->loss_round_start = 1;  /* mark start of new round trip */
-+	}
-+}
-+
-+/* Once per round, reset filter for latest rate and volume of delivered data. */
-+static void bbr_advance_latest_delivery_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* If ACK matches a TLP retransmit, persist the filter. If we detect
-+	 * that a TLP retransmit plugged a tail loss, we'll want to remember
-+	 * how much data the path delivered before the tail loss.
-+	 */
-+	if (bbr->loss_round_start && !rs->is_acking_tlp_retrans_seq) {
-+		bbr->bw_latest = ctx->sample_bw;
-+		bbr->inflight_latest = rs->delivered;
-+	}
-+}
-+
-+/* Update (most of) our congestion signals: track the recent rate and volume of
-+ * delivered data, presence of loss, and EWMA degree of ECN marking.
-+ */
-+static void bbr_update_congestion_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u64 bw;
-+
-+	if (rs->interval_us <= 0 || !rs->acked_sacked)
-+		return; /* Not a valid observation */
-+	bw = ctx->sample_bw;
-+
-+	if (!rs->is_app_limited || bw >= bbr_max_bw(sk))
-+		bbr_take_max_bw_sample(sk, bw);
-+
-+	bbr->loss_in_round |= (rs->losses > 0);
-+
-+	if (!bbr->loss_round_start)
-+		return;		/* skip the per-round-trip updates */
-+	/* Now do per-round-trip updates. */
-+	bbr_adapt_lower_bounds(sk, rs);
-+
-+	bbr->loss_in_round = 0;
-+	bbr->ecn_in_round  = 0;
-+}
-+
-+/* Bandwidth probing can cause loss. To help coexistence with loss-based
-+ * congestion control we spread out our probing in a Reno-conscious way. Due to
-+ * the shape of the Reno sawtooth, the time required between loss epochs for an
-+ * idealized Reno flow is a number of round trips that is the BDP of that
-+ * flow. We count packet-timed round trips directly, since measured RTT can
-+ * vary widely, and Reno is driven by packet-timed round trips.
-+ */
-+static bool bbr_is_reno_coexistence_probe_time(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 rounds;
-+
-+	/* Random loss can shave some small percentage off of our inflight
-+	 * in each round. To survive this, flows need robust periodic probes.
-+	 */
-+	rounds = min_t(u32, bbr_param(sk, bw_probe_max_rounds), bbr_target_inflight(sk));
-+	return bbr->rounds_since_probe >= rounds;
-+}
-+
-+/* How long do we want to wait before probing for bandwidth (and risking
-+ * loss)? We randomize the wait, for better mixing and fairness convergence.
-+ *
-+ * We bound the Reno-coexistence inter-bw-probe time to be 62-63 round trips.
-+ * This is calculated to allow fairness with a 25Mbps, 30ms Reno flow,
-+ * (eg 4K video to a broadband user):
-+ *   BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets
-+ *
-+ * We bound the BBR-native inter-bw-probe wall clock time to be:
-+ *  (a) higher than 2 sec: to try to avoid causing loss for a long enough time
-+ *      to allow Reno at 30ms to get 4K video bw, the inter-bw-probe time must
-+ *      be at least: 25Mbps * .030sec / (1514bytes) * 0.030sec = 1.9secs
-+ *  (b) lower than 3 sec: to ensure flows can start probing in a reasonable
-+ *      amount of time to discover unutilized bw on human-scale interactive
-+ *      time-scales (e.g. perhaps traffic from a web page download that we
-+ *      were competing with is now complete).
-+ */
-+static void bbr_pick_probe_wait(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Decide the random round-trip bound for wait until probe: */
-+	bbr->rounds_since_probe =
-+		get_random_u32_below(bbr_param(sk, bw_probe_rand_rounds));
-+	/* Decide the random wall clock bound for wait until probe: */
-+	bbr->probe_wait_us = bbr_param(sk, bw_probe_base_us) +
-+			     get_random_u32_below(bbr_param(sk, bw_probe_rand_us));
-+}
-+
-+static void bbr_set_cycle_idx(struct sock *sk, int cycle_idx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->cycle_idx = cycle_idx;
-+	/* New phase, so need to update cwnd and pacing rate. */
-+	bbr->try_fast_path = 0;
-+}
-+
-+/* Send at estimated bw to fill the pipe, but not queue. We need this phase
-+ * before PROBE_UP, because as soon as we send faster than the available bw
-+ * we will start building a queue, and if the buffer is shallow we can cause
-+ * loss. If we do not fill the pipe before we cause this loss, our bw_hi and
-+ * inflight_hi estimates will underestimate.
-+ */
-+static void bbr_start_bw_probe_refill(struct sock *sk, u32 bw_probe_up_rounds)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_lower_bounds(sk);
-+	bbr->bw_probe_up_rounds = bw_probe_up_rounds;
-+	bbr->bw_probe_up_acks = 0;
-+	bbr->stopped_risky_probe = 0;
-+	bbr->ack_phase = BBR_ACKS_REFILLING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_REFILL);
-+}
-+
-+/* Now probe max deliverable data rate and volume. */
-+static void bbr_start_bw_probe_up(struct sock *sk, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->ack_phase = BBR_ACKS_PROBE_STARTING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr->cycle_mstamp = tp->tcp_mstamp;
-+	bbr_reset_full_bw(sk);
-+	bbr->full_bw = ctx->sample_bw;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_UP);
-+	bbr_raise_inflight_hi_slope(sk);
-+}
-+
-+/* Start a new PROBE_BW probing cycle of some wall clock length. Pick a wall
-+ * clock time at which to probe beyond an inflight that we think to be
-+ * safe. This will knowingly risk packet loss, so we want to do this rarely, to
-+ * keep packet loss rates low. Also start a round-trip counter, to probe faster
-+ * if we estimate a Reno flow at our BDP would probe faster.
-+ */
-+static void bbr_start_bw_probe_down(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_congestion_signals(sk);
-+	bbr->bw_probe_up_cnt = ~0U;     /* not growing inflight_hi any more */
-+	bbr_pick_probe_wait(sk);
-+	bbr->cycle_mstamp = tp->tcp_mstamp;		/* start wall clock */
-+	bbr->ack_phase = BBR_ACKS_PROBE_STOPPING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_DOWN);
-+}
-+
-+/* Cruise: maintain what we estimate to be a neutral, conservative
-+ * operating point, without attempting to probe up for bandwidth or down for
-+ * RTT, and only reducing inflight in response to loss/ECN signals.
-+ */
-+static void bbr_start_bw_probe_cruise(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->inflight_lo != ~0U)
-+		bbr->inflight_lo = min(bbr->inflight_lo, bbr->inflight_hi);
-+
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_CRUISE);
-+}
-+
-+/* Loss and/or ECN rate is too high while probing.
-+ * Adapt (once per bw probe) by cutting inflight_hi and then restarting cycle.
-+ */
-+static void bbr_handle_inflight_too_high(struct sock *sk,
-+					  const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	const u32 beta = bbr_param(sk, beta);
-+
-+	bbr->prev_probe_too_high = 1;
-+	bbr->bw_probe_samples = 0;  /* only react once per probe */
-+	/* If we are app-limited then we are not robustly
-+	 * probing the max volume of inflight data we think
-+	 * might be safe (analogous to how app-limited bw
-+	 * samples are not known to be robustly probing bw).
-+	 */
-+	if (!rs->is_app_limited) {
-+		bbr->inflight_hi = max_t(u32, rs->tx_in_flight,
-+					 (u64)bbr_target_inflight(sk) *
-+					 (BBR_UNIT - beta) >> BBR_SCALE);
-+	}
-+	if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP)
-+		bbr_start_bw_probe_down(sk);
-+}
-+
-+/* If we're seeing bw and loss samples reflecting our bw probing, adapt
-+ * using the signals we see. If loss or ECN mark rate gets too high, then adapt
-+ * inflight_hi downward. If we're able to push inflight higher without such
-+ * signals, push higher: adapt inflight_hi upward.
-+ */
-+static bool bbr_adapt_upper_bounds(struct sock *sk,
-+				    const struct rate_sample *rs,
-+				    struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Track when we'll see bw/loss samples resulting from our bw probes. */
-+	if (bbr->ack_phase == BBR_ACKS_PROBE_STARTING && bbr->round_start)
-+		bbr->ack_phase = BBR_ACKS_PROBE_FEEDBACK;
-+	if (bbr->ack_phase == BBR_ACKS_PROBE_STOPPING && bbr->round_start) {
-+		/* End of samples from bw probing phase. */
-+		bbr->bw_probe_samples = 0;
-+		bbr->ack_phase = BBR_ACKS_INIT;
-+		/* At this point in the cycle, our current bw sample is also
-+		 * our best recent chance at finding the highest available bw
-+		 * for this flow. So now is the best time to forget the bw
-+		 * samples from the previous cycle, by advancing the window.
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW && !rs->is_app_limited)
-+			bbr_advance_max_bw_filter(sk);
-+		/* If we had an inflight_hi, then probed and pushed inflight all
-+		 * the way up to hit that inflight_hi without seeing any
-+		 * high loss/ECN in all the resulting ACKs from that probing,
-+		 * then probe up again, this time letting inflight persist at
-+		 * inflight_hi for a round trip, then accelerating beyond.
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW &&
-+		    bbr->stopped_risky_probe && !bbr->prev_probe_too_high) {
-+			bbr_start_bw_probe_refill(sk, 0);
-+			return true;  /* yes, decided state transition */
-+		}
-+	}
-+	if (bbr_is_inflight_too_high(sk, rs)) {
-+		if (bbr->bw_probe_samples)  /*  sample is from bw probing? */
-+			bbr_handle_inflight_too_high(sk, rs);
-+	} else {
-+		/* Loss/ECN rate is declared safe. Adjust upper bound upward. */
-+
-+		if (bbr->inflight_hi == ~0U)
-+			return false;   /* no excess queue signals yet */
-+
-+		/* To be resilient to random loss, we must raise bw/inflight_hi
-+		 * if we observe in any phase that a higher level is safe.
-+		 */
-+		if (rs->tx_in_flight > bbr->inflight_hi) {
-+			bbr->inflight_hi = rs->tx_in_flight;
-+		}
-+
-+		if (bbr->mode == BBR_PROBE_BW &&
-+		    bbr->cycle_idx == BBR_BW_PROBE_UP)
-+			bbr_probe_inflight_hi_upward(sk, rs);
-+	}
-+
-+	return false;
-+}
-+
-+/* Check if it's time to probe for bandwidth now, and if so, kick it off. */
-+static bool bbr_check_time_to_probe_bw(struct sock *sk,
-+					const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 n;
-+
-+	/* If we seem to be at an operating point where we are not seeing loss
-+	 * but we are seeing ECN marks, then when the ECN marks cease we reprobe
-+	 * quickly (in case cross-traffic has ceased and freed up bw).
-+	 */
-+	if (bbr_param(sk, ecn_reprobe_gain) && bbr->ecn_eligible &&
-+	    bbr->ecn_in_cycle && !bbr->loss_in_cycle &&
-+	    inet_csk(sk)->icsk_ca_state == TCP_CA_Open) {
-+		/* Calculate n so that when bbr_raise_inflight_hi_slope()
-+		 * computes growth_this_round as 2^n it will be roughly the
-+		 * desired volume of data (inflight_hi*ecn_reprobe_gain).
-+		 */
-+		n = ilog2((((u64)bbr->inflight_hi *
-+			    bbr_param(sk, ecn_reprobe_gain)) >> BBR_SCALE));
-+		bbr_start_bw_probe_refill(sk, n);
-+		return true;
-+	}
-+
-+	if (bbr_has_elapsed_in_phase(sk, bbr->probe_wait_us) ||
-+	    bbr_is_reno_coexistence_probe_time(sk)) {
-+		bbr_start_bw_probe_refill(sk, 0);
-+		return true;
-+	}
-+	return false;
-+}
-+
-+/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */
-+static bool bbr_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw)
-+{
-+	/* Always need to pull inflight down to leave headroom in queue. */
-+	if (inflight > bbr_inflight_with_headroom(sk))
-+		return false;
-+
-+	return inflight <= bbr_inflight(sk, bw, BBR_UNIT);
-+}
-+
-+/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */
-+static void bbr_update_cycle_phase(struct sock *sk,
-+				    const struct rate_sample *rs,
-+				    struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	bool is_bw_probe_done = false;
-+	u32 inflight, bw;
-+
-+	if (!bbr_full_bw_reached(sk))
-+		return;
-+
-+	/* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */
-+	if (bbr_adapt_upper_bounds(sk, rs, ctx))
-+		return;		/* already decided state transition */
-+
-+	if (bbr->mode != BBR_PROBE_BW)
-+		return;
-+
-+	inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight);
-+	bw = bbr_max_bw(sk);
-+
-+	switch (bbr->cycle_idx) {
-+	/* First we spend most of our time cruising with a pacing_gain of 1.0,
-+	 * which paces at the estimated bw, to try to fully use the pipe
-+	 * without building queue. If we encounter loss/ECN marks, we adapt
-+	 * by slowing down.
-+	 */
-+	case BBR_BW_PROBE_CRUISE:
-+		if (bbr_check_time_to_probe_bw(sk, rs))
-+			return;		/* already decided state transition */
-+		break;
-+
-+	/* After cruising, when it's time to probe, we first "refill": we send
-+	 * at the estimated bw to fill the pipe, before probing higher and
-+	 * knowingly risking overflowing the bottleneck buffer (causing loss).
-+	 */
-+	case BBR_BW_PROBE_REFILL:
-+		if (bbr->round_start) {
-+			/* After one full round trip of sending in REFILL, we
-+			 * start to see bw samples reflecting our REFILL, which
-+			 * may be putting too much data in flight.
-+			 */
-+			bbr->bw_probe_samples = 1;
-+			bbr_start_bw_probe_up(sk, ctx);
-+		}
-+		break;
-+
-+	/* After we refill the pipe, we probe by using a pacing_gain > 1.0, to
-+	 * probe for bw. If we have not seen loss/ECN, we try to raise inflight
-+	 * to at least pacing_gain*BDP; note that this may take more than
-+	 * min_rtt if min_rtt is small (e.g. on a LAN).
-+	 *
-+	 * We terminate PROBE_UP bandwidth probing upon any of the following:
-+	 *
-+	 * (1) We've pushed inflight up to hit the inflight_hi target set in the
-+	 *     most recent previous bw probe phase. Thus we want to start
-+	 *     draining the queue immediately because it's very likely the most
-+	 *     recently sent packets will fill the queue and cause drops.
-+	 * (2) If inflight_hi has not limited bandwidth growth recently, and
-+	 *     yet delivered bandwidth has not increased much recently
-+	 *     (bbr->full_bw_now).
-+	 * (3) Loss filter says loss rate is "too high".
-+	 * (4) ECN filter says ECN mark rate is "too high".
-+	 *
-+	 * (1) (2) checked here, (3) (4) checked in bbr_is_inflight_too_high()
-+	 */
-+	case BBR_BW_PROBE_UP:
-+		if (bbr->prev_probe_too_high &&
-+		    inflight >= bbr->inflight_hi) {
-+			bbr->stopped_risky_probe = 1;
-+			is_bw_probe_done = true;
-+		} else {
-+			if (tp->is_cwnd_limited &&
-+			    tcp_snd_cwnd(tp) >= bbr->inflight_hi) {
-+				/* inflight_hi is limiting bw growth */
-+				bbr_reset_full_bw(sk);
-+				bbr->full_bw = ctx->sample_bw;
-+			} else if (bbr->full_bw_now) {
-+				/* Plateau in estimated bw. Pipe looks full. */
-+				is_bw_probe_done = true;
-+			}
-+		}
-+		if (is_bw_probe_done) {
-+			bbr->prev_probe_too_high = 0;  /* no loss/ECN (yet) */
-+			bbr_start_bw_probe_down(sk);  /* restart w/ down */
-+		}
-+		break;
-+
-+	/* After probing in PROBE_UP, we have usually accumulated some data in
-+	 * the bottleneck buffer (if bw probing didn't find more bw). We next
-+	 * enter PROBE_DOWN to try to drain any excess data from the queue. To
-+	 * do this, we use a pacing_gain < 1.0. We hold this pacing gain until
-+	 * our inflight is less then that target cruising point, which is the
-+	 * minimum of (a) the amount needed to leave headroom, and (b) the
-+	 * estimated BDP. Once inflight falls to match the target, we estimate
-+	 * the queue is drained; persisting would underutilize the pipe.
-+	 */
-+	case BBR_BW_PROBE_DOWN:
-+		if (bbr_check_time_to_probe_bw(sk, rs))
-+			return;		/* already decided state transition */
-+		if (bbr_check_time_to_cruise(sk, inflight, bw))
-+			bbr_start_bw_probe_cruise(sk);
-+		break;
-+
-+	default:
-+		WARN_ONCE(1, "BBR invalid cycle index %u\n", bbr->cycle_idx);
-+	}
-+}
-+
-+/* Exiting PROBE_RTT, so return to bandwidth probing in STARTUP or PROBE_BW. */
-+static void bbr_exit_probe_rtt(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_lower_bounds(sk);
-+	if (bbr_full_bw_reached(sk)) {
-+		bbr->mode = BBR_PROBE_BW;
-+		/* Raising inflight after PROBE_RTT may cause loss, so reset
-+		 * the PROBE_BW clock and schedule the next bandwidth probe for
-+		 * a friendly and randomized future point in time.
-+		 */
-+		bbr_start_bw_probe_down(sk);
-+		/* Since we are exiting PROBE_RTT, we know inflight is
-+		 * below our estimated BDP, so it is reasonable to cruise.
-+		 */
-+		bbr_start_bw_probe_cruise(sk);
-+	} else {
-+		bbr->mode = BBR_STARTUP;
-+	}
-+}
-+
-+/* Exit STARTUP based on loss rate > 1% and loss gaps in round >= N. Wait until
-+ * the end of the round in recovery to get a good estimate of how many packets
-+ * have been lost, and how many we need to drain with a low pacing rate.
-+ */
-+static void bbr_check_loss_too_high_in_startup(struct sock *sk,
-+						const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr_full_bw_reached(sk))
-+		return;
-+
-+	/* For STARTUP exit, check the loss rate at the end of each round trip
-+	 * of Recovery episodes in STARTUP. We check the loss rate at the end
-+	 * of the round trip to filter out noisy/low loss and have a better
-+	 * sense of inflight (extent of loss), so we can drain more accurately.
-+	 */
-+	if (rs->losses && bbr->loss_events_in_round < 0xf)
-+		bbr->loss_events_in_round++;  /* update saturating counter */
-+	if (bbr_param(sk, full_loss_cnt) && bbr->loss_round_start &&
-+	    inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery &&
-+	    bbr->loss_events_in_round >= bbr_param(sk, full_loss_cnt) &&
-+	    bbr_is_inflight_too_high(sk, rs)) {
-+		bbr_handle_queue_too_high_in_startup(sk);
-+		return;
-+	}
-+	if (bbr->loss_round_start)
-+		bbr->loss_events_in_round = 0;
-+}
-+
-+/* Estimate when the pipe is full, using the change in delivery rate: BBR
-+ * estimates bw probing filled the pipe if the estimated bw hasn't changed by
-+ * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited
-+ * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the
-+ * higher rwin, 3: we get higher delivery rate samples. Or transient
-+ * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar
-+ * design goal, but uses delay and inter-ACK spacing instead of bandwidth.
-+ */
-+static void bbr_check_full_bw_reached(struct sock *sk,
-+				       const struct rate_sample *rs,
-+				       struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bw_thresh, full_cnt, thresh;
-+
-+	if (bbr->full_bw_now || rs->is_app_limited)
-+		return;
-+
-+	thresh = bbr_param(sk, full_bw_thresh);
-+	full_cnt = bbr_param(sk, full_bw_cnt);
-+	bw_thresh = (u64)bbr->full_bw * thresh >> BBR_SCALE;
-+	if (ctx->sample_bw >= bw_thresh) {
-+		bbr_reset_full_bw(sk);
-+		bbr->full_bw = ctx->sample_bw;
-+		return;
-+	}
-+	if (!bbr->round_start)
-+		return;
-+	++bbr->full_bw_cnt;
-+	bbr->full_bw_now = bbr->full_bw_cnt >= full_cnt;
-+	bbr->full_bw_reached |= bbr->full_bw_now;
-+}
-+
-+/* If pipe is probably full, drain the queue and then enter steady-state. */
-+static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs,
-+			    struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) {
-+		bbr->mode = BBR_DRAIN;	/* drain queue we created */
-+		/* Set ssthresh to export purely for monitoring, to signal
-+		 * completion of initial STARTUP by setting to a non-
-+		 * TCP_INFINITE_SSTHRESH value (ssthresh is not used by BBR).
-+		 */
-+		tcp_sk(sk)->snd_ssthresh =
-+				bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+		bbr_reset_congestion_signals(sk);
-+	}	/* fall through to check if in-flight is already small: */
-+	if (bbr->mode == BBR_DRAIN &&
-+	    bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <=
-+	    bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) {
-+		bbr->mode = BBR_PROBE_BW;
-+		bbr_start_bw_probe_down(sk);
-+	}
-+}
-+
-+static void bbr_update_model(struct sock *sk, const struct rate_sample *rs,
-+			      struct bbr_context *ctx)
-+{
-+	bbr_update_congestion_signals(sk, rs, ctx);
-+	bbr_update_ack_aggregation(sk, rs);
-+	bbr_check_loss_too_high_in_startup(sk, rs);
-+	bbr_check_full_bw_reached(sk, rs, ctx);
-+	bbr_check_drain(sk, rs, ctx);
-+	bbr_update_cycle_phase(sk, rs, ctx);
-+	bbr_update_min_rtt(sk, rs);
-+}
-+
-+/* Fast path for app-limited case.
-+ *
-+ * On each ack, we execute bbr state machine, which primarily consists of:
-+ * 1) update model based on new rate sample, and
-+ * 2) update control based on updated model or state change.
-+ *
-+ * There are certain workload/scenarios, e.g. app-limited case, where
-+ * either we can skip updating model or we can skip update of both model
-+ * as well as control. This provides signifcant softirq cpu savings for
-+ * processing incoming acks.
-+ *
-+ * In case of app-limited, if there is no congestion (loss/ecn) and
-+ * if observed bw sample is less than current estimated bw, then we can
-+ * skip some of the computation in bbr state processing:
-+ *
-+ * - if there is no rtt/mode/phase change: In this case, since all the
-+ *   parameters of the network model are constant, we can skip model
-+ *   as well control update.
-+ *
-+ * - else we can skip rest of the model update. But we still need to
-+ *   update the control to account for the new rtt/mode/phase.
-+ *
-+ * Returns whether we can take fast path or not.
-+ */
-+static bool bbr_run_fast_path(struct sock *sk, bool *update_model,
-+		const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 prev_min_rtt_us, prev_mode;
-+
-+	if (bbr_param(sk, fast_path) && bbr->try_fast_path &&
-+	    rs->is_app_limited && ctx->sample_bw < bbr_max_bw(sk) &&
-+	    !bbr->loss_in_round && !bbr->ecn_in_round ) {
-+		prev_mode = bbr->mode;
-+		prev_min_rtt_us = bbr->min_rtt_us;
-+		bbr_check_drain(sk, rs, ctx);
-+		bbr_update_cycle_phase(sk, rs, ctx);
-+		bbr_update_min_rtt(sk, rs);
-+
-+		if (bbr->mode == prev_mode &&
-+		    bbr->min_rtt_us == prev_min_rtt_us &&
-+		    bbr->try_fast_path) {
-+			return true;
-+		}
-+
-+		/* Skip model update, but control still needs to be updated */
-+		*update_model = false;
-+	}
-+	return false;
-+}
-+
-+__bpf_kfunc static void bbr_main(struct sock *sk, u32 ack, int flag,
-+				 const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct bbr_context ctx = { 0 };
-+	bool update_model = true;
-+	u32 bw, round_delivered;
-+	int ce_ratio = -1;
-+
-+	round_delivered = bbr_update_round_start(sk, rs, &ctx);
-+	if (bbr->round_start) {
-+		bbr->rounds_since_probe =
-+			min_t(s32, bbr->rounds_since_probe + 1, 0xFF);
-+		ce_ratio = bbr_update_ecn_alpha(sk);
-+	}
-+	bbr_plb(sk, rs, ce_ratio);
-+
-+	bbr->ecn_in_round  |= (bbr->ecn_eligible && rs->is_ece);
-+	bbr_calculate_bw_sample(sk, rs, &ctx);
-+	bbr_update_latest_delivery_signals(sk, rs, &ctx);
-+
-+	if (bbr_run_fast_path(sk, &update_model, rs, &ctx))
-+		goto out;
-+
-+	if (update_model)
-+		bbr_update_model(sk, rs, &ctx);
-+
-+	bbr_update_gains(sk);
-+	bw = bbr_bw(sk);
-+	bbr_set_pacing_rate(sk, bw, bbr->pacing_gain);
-+	bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain,
-+		     tcp_snd_cwnd(tp), &ctx);
-+	bbr_bound_cwnd_for_inflight_model(sk);
-+
-+out:
-+	bbr_advance_latest_delivery_signals(sk, rs, &ctx);
-+	bbr->prev_ca_state = inet_csk(sk)->icsk_ca_state;
-+	bbr->loss_in_cycle |= rs->lost > 0;
-+	bbr->ecn_in_cycle  |= rs->delivered_ce > 0;
-+}
-+
-+__bpf_kfunc static void bbr_init(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->initialized = 1;
-+
-+	bbr->init_cwnd = min(0x7FU, tcp_snd_cwnd(tp));
-+	bbr->prior_cwnd = tp->prior_cwnd;
-+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr->prev_ca_state = TCP_CA_Open;
-+
-+	bbr->probe_rtt_done_stamp = 0;
-+	bbr->probe_rtt_round_done = 0;
-+	bbr->probe_rtt_min_us = tcp_min_rtt(tp);
-+	bbr->probe_rtt_min_stamp = tcp_jiffies32;
-+	bbr->min_rtt_us = tcp_min_rtt(tp);
-+	bbr->min_rtt_stamp = tcp_jiffies32;
-+
-+	bbr->has_seen_rtt = 0;
-+	bbr_init_pacing_rate_from_rtt(sk);
-+
-+	bbr->round_start = 0;
-+	bbr->idle_restart = 0;
-+	bbr->full_bw_reached = 0;
-+	bbr->full_bw = 0;
-+	bbr->full_bw_cnt = 0;
-+	bbr->cycle_mstamp = 0;
-+	bbr->cycle_idx = 0;
-+
-+	bbr_reset_startup_mode(sk);
-+
-+	bbr->ack_epoch_mstamp = tp->tcp_mstamp;
-+	bbr->ack_epoch_acked = 0;
-+	bbr->extra_acked_win_rtts = 0;
-+	bbr->extra_acked_win_idx = 0;
-+	bbr->extra_acked[0] = 0;
-+	bbr->extra_acked[1] = 0;
-+
-+	bbr->ce_state = 0;
-+	bbr->prior_rcv_nxt = tp->rcv_nxt;
-+	bbr->try_fast_path = 0;
-+
-+	cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED);
-+
-+	/* Start sampling ECN mark rate after first full flight is ACKed: */
-+	bbr->loss_round_delivered = tp->delivered + 1;
-+	bbr->loss_round_start = 0;
-+	bbr->undo_bw_lo = 0;
-+	bbr->undo_inflight_lo = 0;
-+	bbr->undo_inflight_hi = 0;
-+	bbr->loss_events_in_round = 0;
-+	bbr->startup_ecn_rounds = 0;
-+	bbr_reset_congestion_signals(sk);
-+	bbr->bw_lo = ~0U;
-+	bbr->bw_hi[0] = 0;
-+	bbr->bw_hi[1] = 0;
-+	bbr->inflight_lo = ~0U;
-+	bbr->inflight_hi = ~0U;
-+	bbr_reset_full_bw(sk);
-+	bbr->bw_probe_up_cnt = ~0U;
-+	bbr->bw_probe_up_acks = 0;
-+	bbr->bw_probe_up_rounds = 0;
-+	bbr->probe_wait_us = 0;
-+	bbr->stopped_risky_probe = 0;
-+	bbr->ack_phase = BBR_ACKS_INIT;
-+	bbr->rounds_since_probe = 0;
-+	bbr->bw_probe_samples = 0;
-+	bbr->prev_probe_too_high = 0;
-+	bbr->ecn_eligible = 0;
-+	bbr->ecn_alpha = bbr_param(sk, ecn_alpha_init);
-+	bbr->alpha_last_delivered = 0;
-+	bbr->alpha_last_delivered_ce = 0;
-+	bbr->plb.pause_until = 0;
-+
-+	tp->fast_ack_mode = bbr_fast_ack_mode ? 1 : 0;
-+
-+	if (bbr_can_use_ecn(sk))
-+		tp->ecn_flags |= TCP_ECN_ECT_PERMANENT;
-+}
-+
-+/* BBR marks the current round trip as a loss round. */
-+static void bbr_note_loss(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Capture "current" data over the full round trip of loss, to
-+	 * have a better chance of observing the full capacity of the path.
-+	 */
-+	if (!bbr->loss_in_round)  /* first loss in this round trip? */
-+		bbr->loss_round_delivered = tp->delivered;  /* set round trip */
-+	bbr->loss_in_round = 1;
-+	bbr->loss_in_cycle = 1;
-+}
-+
-+/* Core TCP stack informs us that the given skb was just marked lost. */
-+__bpf_kfunc static void bbr_skb_marked_lost(struct sock *sk,
-+					    const struct sk_buff *skb)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
-+	struct rate_sample rs = {};
-+
-+	bbr_note_loss(sk);
-+
-+	if (!bbr->bw_probe_samples)
-+		return;  /* not an skb sent while probing for bandwidth */
-+	if (unlikely(!scb->tx.delivered_mstamp))
-+		return;  /* skb was SACKed, reneged, marked lost; ignore it */
-+	/* We are probing for bandwidth. Construct a rate sample that
-+	 * estimates what happened in the flight leading up to this lost skb,
-+	 * then see if the loss rate went too high, and if so at which packet.
-+	 */
-+	rs.tx_in_flight = scb->tx.in_flight;
-+	rs.lost = tp->lost - scb->tx.lost;
-+	rs.is_app_limited = scb->tx.is_app_limited;
-+	if (bbr_is_inflight_too_high(sk, &rs)) {
-+		rs.tx_in_flight = bbr_inflight_hi_from_lost_skb(sk, &rs, skb);
-+		bbr_handle_inflight_too_high(sk, &rs);
-+	}
-+}
-+
-+static void bbr_run_loss_probe_recovery(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct rate_sample rs = {0};
-+
-+	bbr_note_loss(sk);
-+
-+	if (!bbr->bw_probe_samples)
-+		return;  /* not sent while probing for bandwidth */
-+	/* We are probing for bandwidth. Construct a rate sample that
-+	 * estimates what happened in the flight leading up to this
-+	 * loss, then see if the loss rate went too high.
-+	 */
-+	rs.lost = 1;	/* TLP probe repaired loss of a single segment */
-+	rs.tx_in_flight = bbr->inflight_latest + rs.lost;
-+	rs.is_app_limited = tp->tlp_orig_data_app_limited;
-+	if (bbr_is_inflight_too_high(sk, &rs))
-+		bbr_handle_inflight_too_high(sk, &rs);
-+}
-+
-+/* Revert short-term model if current loss recovery event was spurious. */
-+__bpf_kfunc static u32 bbr_undo_cwnd(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_full_bw(sk); /* spurious slow-down; reset full bw detector */
-+	bbr->loss_in_round = 0;
-+
-+	/* Revert to cwnd and other state saved before loss episode. */
-+	bbr->bw_lo = max(bbr->bw_lo, bbr->undo_bw_lo);
-+	bbr->inflight_lo = max(bbr->inflight_lo, bbr->undo_inflight_lo);
-+	bbr->inflight_hi = max(bbr->inflight_hi, bbr->undo_inflight_hi);
-+	bbr->try_fast_path = 0;  /* take slow path to set proper cwnd, pacing */
-+	return bbr->prior_cwnd;
-+}
-+
-+/* Entering loss recovery, so save state for when we undo recovery. */
-+__bpf_kfunc static u32 bbr_ssthresh(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_save_cwnd(sk);
-+	/* For undo, save state that adapts based on loss signal. */
-+	bbr->undo_bw_lo		= bbr->bw_lo;
-+	bbr->undo_inflight_lo	= bbr->inflight_lo;
-+	bbr->undo_inflight_hi	= bbr->inflight_hi;
-+	return tcp_sk(sk)->snd_ssthresh;
-+}
-+
-+static enum tcp_bbr_phase bbr_get_phase(struct bbr *bbr)
-+{
-+	switch (bbr->mode) {
-+	case BBR_STARTUP:
-+		return BBR_PHASE_STARTUP;
-+	case BBR_DRAIN:
-+		return BBR_PHASE_DRAIN;
-+	case BBR_PROBE_BW:
-+		break;
-+	case BBR_PROBE_RTT:
-+		return BBR_PHASE_PROBE_RTT;
-+	default:
-+		return BBR_PHASE_INVALID;
-+	}
-+	switch (bbr->cycle_idx) {
-+	case BBR_BW_PROBE_UP:
-+		return BBR_PHASE_PROBE_BW_UP;
-+	case BBR_BW_PROBE_DOWN:
-+		return BBR_PHASE_PROBE_BW_DOWN;
-+	case BBR_BW_PROBE_CRUISE:
-+		return BBR_PHASE_PROBE_BW_CRUISE;
-+	case BBR_BW_PROBE_REFILL:
-+		return BBR_PHASE_PROBE_BW_REFILL;
-+	default:
-+		return BBR_PHASE_INVALID;
-+	}
-+}
-+
-+static size_t bbr_get_info(struct sock *sk, u32 ext, int *attr,
-+			    union tcp_cc_info *info)
-+{
-+	if (ext & (1 << (INET_DIAG_BBRINFO - 1)) ||
-+	    ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
-+		struct bbr *bbr = inet_csk_ca(sk);
-+		u64 bw = bbr_bw_bytes_per_sec(sk, bbr_bw(sk));
-+		u64 bw_hi = bbr_bw_bytes_per_sec(sk, bbr_max_bw(sk));
-+		u64 bw_lo = bbr->bw_lo == ~0U ?
-+			~0ULL : bbr_bw_bytes_per_sec(sk, bbr->bw_lo);
-+		struct tcp_bbr_info *bbr_info = &info->bbr;
-+
-+		memset(bbr_info, 0, sizeof(*bbr_info));
-+		bbr_info->bbr_bw_lo		= (u32)bw;
-+		bbr_info->bbr_bw_hi		= (u32)(bw >> 32);
-+		bbr_info->bbr_min_rtt		= bbr->min_rtt_us;
-+		bbr_info->bbr_pacing_gain	= bbr->pacing_gain;
-+		bbr_info->bbr_cwnd_gain		= bbr->cwnd_gain;
-+		bbr_info->bbr_bw_hi_lsb		= (u32)bw_hi;
-+		bbr_info->bbr_bw_hi_msb		= (u32)(bw_hi >> 32);
-+		bbr_info->bbr_bw_lo_lsb		= (u32)bw_lo;
-+		bbr_info->bbr_bw_lo_msb		= (u32)(bw_lo >> 32);
-+		bbr_info->bbr_mode		= bbr->mode;
-+		bbr_info->bbr_phase		= (__u8)bbr_get_phase(bbr);
-+		bbr_info->bbr_version		= (__u8)BBR_VERSION;
-+		bbr_info->bbr_inflight_lo	= bbr->inflight_lo;
-+		bbr_info->bbr_inflight_hi	= bbr->inflight_hi;
-+		bbr_info->bbr_extra_acked	= bbr_extra_acked(sk);
-+		*attr = INET_DIAG_BBRINFO;
-+		return sizeof(*bbr_info);
-+	}
-+	return 0;
-+}
-+
-+__bpf_kfunc static void bbr_set_state(struct sock *sk, u8 new_state)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (new_state == TCP_CA_Loss) {
-+
-+		bbr->prev_ca_state = TCP_CA_Loss;
-+		tcp_plb_update_state_upon_rto(sk, &bbr->plb);
-+		/* The tcp_write_timeout() call to sk_rethink_txhash() likely
-+		 * repathed this flow, so re-learn the min network RTT on the
-+		 * new path:
-+		 */
-+		bbr_reset_full_bw(sk);
-+		if (!bbr_is_probing_bandwidth(sk) && bbr->inflight_lo == ~0U) {
-+			/* bbr_adapt_lower_bounds() needs cwnd before
-+			 * we suffered an RTO, to update inflight_lo:
-+			 */
-+			bbr->inflight_lo =
-+				max(tcp_snd_cwnd(tp), bbr->prior_cwnd);
-+		}
-+	} else if (bbr->prev_ca_state == TCP_CA_Loss &&
-+		   new_state != TCP_CA_Loss) {
-+		bbr_exit_loss_recovery(sk);
-+	}
-+}
-+
-+
-+static struct tcp_congestion_ops tcp_bbrv3_cong_ops __read_mostly = {
-+	.flags		= TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS,
-+	.name		= "bbrv3",
-+	.owner		= THIS_MODULE,
-+	.init		= bbr_init,
-+	.cong_control	= bbr_main,
-+	.sndbuf_expand	= bbr_sndbuf_expand,
-+	.skb_marked_lost = bbr_skb_marked_lost,
-+	.undo_cwnd	= bbr_undo_cwnd,
-+	.cwnd_event	= bbr_cwnd_event,
-+	.ssthresh	= bbr_ssthresh,
-+	.tso_segs	= bbr_tso_segs,
-+	.get_info	= bbr_get_info,
-+	.set_state	= bbr_set_state,
-+};
-+
-+BTF_KFUNCS_START(tcp_bbrv3_check_kfunc_ids)
-+BTF_ID_FLAGS(func, bbr_init)
-+BTF_ID_FLAGS(func, bbr_main)
-+BTF_ID_FLAGS(func, bbr_sndbuf_expand)
-+BTF_ID_FLAGS(func, bbr_skb_marked_lost)
-+BTF_ID_FLAGS(func, bbr_undo_cwnd)
-+BTF_ID_FLAGS(func, bbr_cwnd_event)
-+BTF_ID_FLAGS(func, bbr_ssthresh)
-+BTF_ID_FLAGS(func, bbr_tso_segs)
-+BTF_ID_FLAGS(func, bbr_set_state)
-+BTF_KFUNCS_END(tcp_bbrv3_check_kfunc_ids)
-+
-+static const struct btf_kfunc_id_set tcp_bbrv3_kfunc_set = {
-+	.owner = THIS_MODULE,
-+	.set   = &tcp_bbrv3_check_kfunc_ids,
-+};
-+
-+static int __init bbrv3_register(void)
-+{
-+	int ret;
-+
-+	BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE);
-+
-+	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &tcp_bbrv3_kfunc_set);
-+	if (ret < 0)
-+		return ret;
-+	return tcp_register_congestion_control(&tcp_bbrv3_cong_ops);
-+}
-+
-+static void __exit bbrv3_unregister(void)
-+{
-+	tcp_unregister_congestion_control(&tcp_bbrv3_cong_ops);
-+}
-+
-+module_init(bbrv3_register);
-+module_exit(bbrv3_unregister);
-+
-+MODULE_AUTHOR("Van Jacobson <vanj@google.com>");
-+MODULE_AUTHOR("Neal Cardwell <ncardwell@google.com>");
-+MODULE_AUTHOR("Yuchung Cheng <ycheng@google.com>");
-+MODULE_AUTHOR("Soheil Hassas Yeganeh <soheil@google.com>");
-+MODULE_AUTHOR("Priyaranjan Jha <priyarjha@google.com>");
-+MODULE_AUTHOR("Yousuk Seung <ysseung@google.com>");
-+MODULE_AUTHOR("Kevin Yang <yyd@google.com>");
-+MODULE_AUTHOR("Arjun Roy <arjunroy@google.com>");
-+MODULE_AUTHOR("David Morley <morleyd@google.com>");
-+
-+MODULE_LICENSE("Dual BSD/GPL");
-+MODULE_DESCRIPTION("TCP BBRv3 (Bottleneck Bandwidth and RTT Version 3)");
-+MODULE_VERSION(__stringify(BBR_VERSION));

bbrv3.patch

@@ -1,2604 +0,0 @@
-diff --git a/include/net/tcp.h b/include/net/tcp.h
-index afe1ca2cc..8eebfafdd 100644
---- a/include/net/tcp.h
-+++ b/include/net/tcp.h
-@@ -1112,6 +1112,12 @@ struct tcp_congestion_ops {
- 	/* override sysctl_tcp_min_tso_segs */
- 	u32 (*min_tso_segs)(struct sock *sk);
- 
-+	/* call when skb is marked lost (optional) */
-+	void (*skb_marked_lost)(struct sock *sk, const struct sk_buff *skb);
-+
-+	/* set TSO segment count (optional, for new congestion controls) */
-+	u32 (*tso_segs)(struct sock *sk, unsigned int mss_now);
-+
- 	/* call when packets are delivered to update cwnd and pacing rate,
- 	 * after all the ca_state processing. (optional)
- 	 */
-diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
-index 50655de04..8d69bd9b7 100644
---- a/include/uapi/linux/inet_diag.h
-+++ b/include/uapi/linux/inet_diag.h
-@@ -223,12 +223,37 @@ struct tcp_dctcp_info {
- /* INET_DIAG_BBRINFO */
- 
- struct tcp_bbr_info {
-+	/* Original 6 fields - unchanged offsets for ABI backward compatibility */
- 	/* u64 bw: max-filtered BW (app throughput) estimate in Byte per sec: */
- 	__u32	bbr_bw_lo;		/* lower 32 bits of bw */
- 	__u32	bbr_bw_hi;		/* upper 32 bits of bw */
- 	__u32	bbr_min_rtt;		/* min-filtered RTT in uSec */
- 	__u32	bbr_pacing_gain;	/* pacing gain shifted left 8 bits */
- 	__u32	bbr_cwnd_gain;		/* cwnd gain shifted left 8 bits */
-+	/* BBRv3+ new fields - appended for extended information */
-+	__u32	bbr_bw_hi_lsb;		/* lower 32 bits of bw_hi */
-+	__u32	bbr_bw_hi_msb;		/* upper 32 bits of bw_hi */
-+	__u32	bbr_bw_lo_lsb;		/* lower 32 bits of bw_lo */
-+	__u32	bbr_bw_lo_msb;		/* upper 32 bits of bw_lo */
-+	__u8	bbr_mode;		/* current bbr_mode in state machine */
-+	__u8	bbr_phase;		/* current state machine phase */
-+	__u8	unused1;		/* alignment padding; not used yet */
-+	__u8	bbr_version;		/* BBR algorithm version */
-+	__u32	bbr_inflight_lo;	/* lower short-term data volume bound */
-+	__u32	bbr_inflight_hi;	/* higher long-term data volume bound */
-+	__u32	bbr_extra_acked;	/* max excess packets ACKed in epoch */
-+};
-+
-+/* TCP BBR congestion control bbr_phase as reported in netlink/ss stats */
-+enum tcp_bbr_phase {
-+	BBR_PHASE_INVALID		= 0,
-+	BBR_PHASE_STARTUP		= 1,
-+	BBR_PHASE_DRAIN			= 2,
-+	BBR_PHASE_PROBE_RTT		= 3,
-+	BBR_PHASE_PROBE_BW_UP		= 4,
-+	BBR_PHASE_PROBE_BW_DOWN		= 5,
-+	BBR_PHASE_PROBE_BW_CRUISE	= 6,
-+	BBR_PHASE_PROBE_BW_REFILL	= 7,
- };
- 
- union tcp_cc_info {
-diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
-index 2dfb12230..afc41f6f7 100644
---- a/net/ipv4/Kconfig
-+++ b/net/ipv4/Kconfig
-@@ -678,6 +678,27 @@ config TCP_CONG_BBR
- 	  AQM schemes that do not provide a delay signal. It requires the fq
- 	  ("Fair Queue") pacing packet scheduler.
- 
-+config TCP_CONG_BBRV3
-+	bool "BBRv3 TCP"
-+	default y
-+	depends on TCP_CONG_BBR || TCP_CONG_BBR=y
-+	help
-+	  BBRv3 (Bottleneck Bandwidth and RTT version 3) TCP congestion
-+	  control. This is an enhanced version of BBR with improved
-+	  fairness, ECN support, and loss handling.
-+
-+	  BBRv3 builds on BBRv1 with additional features:
-+	    - Rate probing with bounded risk of loss
-+	    - ECN-aware congestion avoidance
-+	    - Improved fairness with Reno/CUBIC flows
-+	    - Loss detection and recovery improvements
-+
-+	  To use this module, you must also have:
-+	    - FQ pacing scheduler (CONFIG_NET_SCH_FQ)
-+	    - Optionally: ECN support (CONFIG_TCP_ECN)
-+
-+	  If unsure, say Y.
-+
- choice
- 	prompt "Default TCP congestion control"
- 	default DEFAULT_CUBIC
-@@ -715,6 +736,9 @@ choice
- 	config DEFAULT_BBR
- 		bool "BBR" if TCP_CONG_BBR=y
- 
-+	config DEFAULT_BBRV3
-+		bool "BBRv3" if TCP_CONG_BBRV3=y
-+
- 	config DEFAULT_RENO
- 		bool "Reno"
- endchoice
-@@ -739,6 +763,7 @@ config DEFAULT_TCP_CONG
- 	default "dctcp" if DEFAULT_DCTCP
- 	default "cdg" if DEFAULT_CDG
- 	default "bbr" if DEFAULT_BBR
-+	default "bbrv3" if DEFAULT_BBRV3
- 	default "cubic"
- 
- config TCP_MD5SIG
-diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
-index bbdd9c44f..bd5d416a4 100644
---- a/net/ipv4/Makefile
-+++ b/net/ipv4/Makefile
-@@ -46,6 +46,7 @@ obj-$(CONFIG_INET_TCP_DIAG) += tcp_diag.o
- obj-$(CONFIG_INET_UDP_DIAG) += udp_diag.o
- obj-$(CONFIG_INET_RAW_DIAG) += raw_diag.o
- obj-$(CONFIG_TCP_CONG_BBR) += tcp_bbr.o
-+obj-$(CONFIG_TCP_CONG_BBRV3) += tcp_bbrv3.o
- obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
- obj-$(CONFIG_TCP_CONG_CDG) += tcp_cdg.o
- obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o
-diff --git a/net/ipv4/tcp_dctcp.h b/net/ipv4/tcp_dctcp.h
-index d69a77cbd..b99744ea9 100644
---- a/net/ipv4/tcp_dctcp.h
-+++ b/net/ipv4/tcp_dctcp.h
-@@ -1,6 +1,14 @@
-+/* SPDX-License-Identifier: GPL-2.0 */
- #ifndef _TCP_DCTCP_H
- #define _TCP_DCTCP_H
- 
-+/*
-+ * DCTCP ECE ACK helper functions for BBRv3
-+ *
-+ * These functions implement the minimal DCTP CE state machine needed
-+ * by BBRv3 for ECN-based congestion avoidance.
-+ */
-+
- static inline void dctcp_ece_ack_cwr(struct sock *sk, u32 ce_state)
- {
- 	struct tcp_sock *tp = tcp_sk(sk);
-@@ -37,4 +45,41 @@ static inline void dctcp_ece_ack_update(struct sock *sk, enum tcp_ca_event evt,
- 	dctcp_ece_ack_cwr(sk, new_ce_state);
- }
- 
--#endif
-+/*
-+ * State for PLB (Protective Load Balancing) for a single TCP connection.
-+ * PLB is an optional feature for datacenter load balancing.
-+ */
-+struct tcp_plb_state {
-+	u8	consec_cong_rounds:5, /* consecutive congested rounds */
-+		pause_until_set:1;	/* pause_until is valid */
-+	u32	pause_until;		/* don't rehash until this jiffie */
-+};
-+
-+static inline void tcp_plb_init(const struct sock *sk,
-+				struct tcp_plb_state *plb)
-+{
-+	memset(plb, 0, sizeof(*plb));
-+}
-+
-+static inline void tcp_plb_update_state(const struct sock *sk,
-+					struct tcp_plb_state *plb,
-+					const int cong_ratio)
-+{
-+	/* PLB is optional - stub implementation for kernels without
-+	 * the full PLB infrastructure (sysctl_tcp_plb_enabled, etc.)
-+	 */
-+}
-+
-+static inline void tcp_plb_check_rehash(struct sock *sk,
-+					struct tcp_plb_state *plb)
-+{
-+	/* Stub - PLB rehash not available without full infrastructure */
-+}
-+
-+static inline void tcp_plb_update_state_upon_rto(struct sock *sk,
-+						 struct tcp_plb_state *plb)
-+{
-+	/* Stub - RTO state update not available without full infrastructure */
-+}
-+
-+#endif /* _TCP_DCTCP_H */
-diff --git a/net/ipv4/tcp_bbrv3.c b/net/ipv4/tcp_bbrv3.c
-new file mode 100644
-index 000000000..b7e8825e1
---- /dev/null
-+++ b/net/ipv4/tcp_bbrv3.c
-@@ -0,0 +1,2415 @@
-+/* BBR (Bottleneck Bandwidth and RTT) congestion control
-+ *
-+ * BBR is a model-based congestion control algorithm that aims for low queues,
-+ * low loss, and (bounded) Reno/CUBIC coexistence. To maintain a model of the
-+ * network path, it uses measurements of bandwidth and RTT, as well as (if they
-+ * occur) packet loss and/or shallow-threshold ECN signals. Note that although
-+ * it can use ECN or loss signals explicitly, it does not require either; it
-+ * can bound its in-flight data based on its estimate of the BDP.
-+ *
-+ * The model has both higher and lower bounds for the operating range:
-+ *   lo: bw_lo, inflight_lo: conservative short-term lower bound
-+ *   hi: bw_hi, inflight_hi: robust long-term upper bound
-+ * The bandwidth-probing time scale is (a) extended dynamically based on
-+ * estimated BDP to improve coexistence with Reno/CUBIC; (b) bounded by
-+ * an interactive wall-clock time-scale to be more scalable and responsive
-+ * than Reno and CUBIC.
-+ *
-+ * Here is a state transition diagram for BBR:
-+ *
-+ *             |
-+ *             V
-+ *    +---> STARTUP  ----+
-+ *    |        |         |
-+ *    |        V         |
-+ *    |      DRAIN   ----+
-+ *    |        |         |
-+ *    |        V         |
-+ *    +---> PROBE_BW ----+
-+ *    |      ^    |      |
-+ *    |      |    |      |
-+ *    |      +----+      |
-+ *    |                  |
-+ *    +---- PROBE_RTT <--+
-+ *
-+ * A BBR flow starts in STARTUP, and ramps up its sending rate quickly.
-+ * When it estimates the pipe is full, it enters DRAIN to drain the queue.
-+ * In steady state a BBR flow only uses PROBE_BW and PROBE_RTT.
-+ * A long-lived BBR flow spends the vast majority of its time remaining
-+ * (repeatedly) in PROBE_BW, fully probing and utilizing the pipe's bandwidth
-+ * in a fair manner, with a small, bounded queue. *If* a flow has been
-+ * continuously sending for the entire min_rtt window, and hasn't seen an RTT
-+ * sample that matches or decreases its min_rtt estimate for 10 seconds, then
-+ * it briefly enters PROBE_RTT to cut inflight to a minimum value to re-probe
-+ * the path's two-way propagation delay (min_rtt). When exiting PROBE_RTT, if
-+ * we estimated that we reached the full bw of the pipe then we enter PROBE_BW;
-+ * otherwise we enter STARTUP to try to fill the pipe.
-+ *
-+ * BBR is described in detail in:
-+ *   "BBR: Congestion-Based Congestion Control",
-+ *   Neal Cardwell, Yuchung Cheng, C. Stephen Gunn, Soheil Hassas Yeganeh,
-+ *   Van Jacobson. ACM Queue, Vol. 14 No. 5, September-October 2016.
-+ *
-+ * There is a public e-mail list for discussing BBR development and testing:
-+ *   https://groups.google.com/forum/#!forum/bbr-dev
-+ *
-+ * NOTE: BBR might be used with the fq qdisc ("man tc-fq") with pacing enabled,
-+ * otherwise TCP stack falls back to an internal pacing using one high
-+ * resolution timer per TCP socket and may use more resources.
-+ */
-+#include <linux/btf.h>
-+#include <linux/btf_ids.h>
-+#include <linux/module.h>
-+#include <net/tcp.h>
-+#include <linux/inet_diag.h>
-+#include <linux/inet.h>
-+#include <linux/random.h>
-+#include <linux/win_minmax.h>
-+
-+#include <trace/events/tcp.h>
-+#include "tcp_dctcp.h"
-+
-+/* BTF kfunc compatibility macros for kernels that don't have the newer BTF API */
-+#ifndef BTF_KFUNCS_START
-+#define BTF_KFUNCS_START(name) BTF_SET8_START(name)
-+#define BTF_KFUNCS_END(name) BTF_SET8_END(name)
-+#define __bpf_kfunc static
-+#endif
-+
-+#define BBR_VERSION		3
-+
-+#define bbr_param(sk,name)	(bbr_ ## name)
-+
-+/* Scale factor for rate in pkt/uSec unit to avoid truncation in bandwidth
-+ * estimation. The rate unit ~= (1500 bytes / 1 usec / 2^24) ~= 715 bps.
-+ * This handles bandwidths from 0.06pps (715bps) to 256Mpps (3Tbps) in a u32.
-+ * Since the minimum window is >=4 packets, the lower bound isn't
-+ * an issue. The upper bound isn't an issue with existing technologies.
-+ */
-+#define BW_SCALE 24
-+#define BW_UNIT (1 << BW_SCALE)
-+
-+#define BBR_SCALE 8	/* scaling factor for fractions in BBR (e.g. gains) */
-+#define BBR_UNIT (1 << BBR_SCALE)
-+
-+/* BBR has the following modes for deciding how fast to send: */
-+enum bbr_mode {
-+	BBR_STARTUP,	/* ramp up sending rate rapidly to fill pipe */
-+	BBR_DRAIN,	/* drain any queue created during startup */
-+	BBR_PROBE_BW,	/* discover, share bw: pace around estimated bw */
-+	BBR_PROBE_RTT,	/* cut inflight to min to probe min_rtt */
-+};
-+
-+/* How does the incoming ACK stream relate to our bandwidth probing? */
-+enum bbr_ack_phase {
-+	BBR_ACKS_INIT,		  /* not probing; not getting probe feedback */
-+	BBR_ACKS_REFILLING,	  /* sending at est. bw to fill pipe */
-+	BBR_ACKS_PROBE_STARTING,  /* inflight rising to probe bw */
-+	BBR_ACKS_PROBE_FEEDBACK,  /* getting feedback from bw probing */
-+	BBR_ACKS_PROBE_STOPPING,  /* stopped probing; still getting feedback */
-+};
-+
-+/* BBR congestion control block */
-+struct bbr {
-+	u32	min_rtt_us;	        /* min RTT in min_rtt_win_sec window */
-+	u32	min_rtt_stamp;	        /* timestamp of min_rtt_us */
-+	u32	probe_rtt_done_stamp;   /* end time for BBR_PROBE_RTT mode */
-+	u32	probe_rtt_min_us;	/* min RTT in probe_rtt_win_ms win */
-+	u32	probe_rtt_min_stamp;	/* timestamp of probe_rtt_min_us*/
-+	u32     next_rtt_delivered; /* scb->tx.delivered at end of round */
-+	u64	cycle_mstamp;	     /* time of this cycle phase start */
-+	u32     mode:2,		     /* current bbr_mode in state machine */
-+		prev_ca_state:3,     /* CA state on previous ACK */
-+		round_start:1,	     /* start of packet-timed tx->ack round? */
-+		ce_state:1,          /* If most recent data has CE bit set */
-+		bw_probe_up_rounds:5,   /* cwnd-limited rounds in PROBE_UP */
-+		try_fast_path:1,	/* can we take fast path? */
-+		idle_restart:1,	     /* restarting after idle? */
-+		probe_rtt_round_done:1,  /* a BBR_PROBE_RTT round at 4 pkts? */
-+		init_cwnd:7,         /* initial cwnd */
-+		unused_1:10;
-+	u32	pacing_gain:10,	/* current gain for setting pacing rate */
-+		cwnd_gain:10,	/* current gain for setting cwnd */
-+		full_bw_reached:1,   /* reached full bw in Startup? */
-+		full_bw_cnt:2,	/* number of rounds without large bw gains */
-+		cycle_idx:2,	/* current index in pacing_gain cycle array */
-+		has_seen_rtt:1, /* have we seen an RTT sample yet? */
-+		unused_2:6;
-+	u32	prior_cwnd;	/* prior cwnd upon entering loss recovery */
-+	u32	full_bw;	/* recent bw, to estimate if pipe is full */
-+
-+	/* For tracking ACK aggregation: */
-+	u64	ack_epoch_mstamp;	/* start of ACK sampling epoch */
-+	u16	extra_acked[2];		/* max excess data ACKed in epoch */
-+	u32	ack_epoch_acked:20,	/* packets (S)ACKed in sampling epoch */
-+		extra_acked_win_rtts:5,	/* age of extra_acked, in round trips */
-+		extra_acked_win_idx:1,	/* current index in extra_acked array */
-+	/* BBR v3 state: */
-+		full_bw_now:1,		/* recently reached full bw plateau? */
-+		startup_ecn_rounds:2,	/* consecutive hi ECN STARTUP rounds */
-+		loss_in_cycle:1,	/* packet loss in this cycle? */
-+		ecn_in_cycle:1,		/* ECN in this cycle? */
-+		unused_3:1;
-+	u32	loss_round_delivered; /* scb->tx.delivered ending loss round */
-+	u32	undo_bw_lo;	     /* bw_lo before latest losses */
-+	u32	undo_inflight_lo;    /* inflight_lo before latest losses */
-+	u32	undo_inflight_hi;    /* inflight_hi before latest losses */
-+	u32	bw_latest;	 /* max delivered bw in last round trip */
-+	u32	bw_lo;		 /* lower bound on sending bandwidth */
-+	u32	bw_hi[2];	 /* max recent measured bw sample */
-+	u32	inflight_latest; /* max delivered data in last round trip */
-+	u32	inflight_lo;	 /* lower bound of inflight data range */
-+	u32	inflight_hi;	 /* upper bound of inflight data range */
-+	u32	bw_probe_up_cnt; /* packets delivered per inflight_hi incr */
-+	u32	bw_probe_up_acks;  /* packets (S)ACKed since inflight_hi incr */
-+	u32	probe_wait_us;	 /* PROBE_DOWN until next clock-driven probe */
-+	u32	prior_rcv_nxt;	/* tp->rcv_nxt when CE state last changed */
-+	u32	ecn_eligible:1,	/* sender can use ECN (RTT, handshake)? */
-+		ecn_alpha:9,	/* EWMA delivered_ce/delivered; 0..256 */
-+		bw_probe_samples:1,    /* rate samples reflect bw probing? */
-+		prev_probe_too_high:1, /* did last PROBE_UP go too high? */
-+		stopped_risky_probe:1, /* last PROBE_UP stopped due to risk? */
-+		rounds_since_probe:8,  /* packet-timed rounds since probed bw */
-+		loss_round_start:1,    /* loss_round_delivered round trip? */
-+		loss_in_round:1,       /* loss marked in this round trip? */
-+		ecn_in_round:1,	       /* ECN marked in this round trip? */
-+		ack_phase:3,	       /* bbr_ack_phase: meaning of ACKs */
-+		loss_events_in_round:4,/* losses in STARTUP round */
-+		initialized:1;	       /* has bbr_init() been called? */
-+	u32	alpha_last_delivered;	 /* tp->delivered    at alpha update */
-+	u32	alpha_last_delivered_ce; /* tp->delivered_ce at alpha update */
-+
-+	u8	unused_4;		/* to preserve alignment */
-+	struct tcp_plb_state plb;
-+};
-+
-+struct bbr_context {
-+	u32 sample_bw;
-+};
-+
-+/* Window length of min_rtt filter (in sec): */
-+static const u32 bbr_min_rtt_win_sec = 10;
-+/* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode: */
-+static const u32 bbr_probe_rtt_mode_ms = 200;
-+/* Window length of probe_rtt_min_us filter (in ms), and consequently the
-+ * typical interval between PROBE_RTT mode entries. The default is 5000ms.
-+ * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC
-+ */
-+static const u32 bbr_probe_rtt_win_ms = 5000;
-+/* Proportion of cwnd to estimated BDP in PROBE_RTT, in units of BBR_UNIT: */
-+static const u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2;
-+
-+/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting
-+ * in bigger TSO bursts. We cut the RTT-based allowance in half
-+ * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance
-+ * is below 1500 bytes after 6 * ~500 usec = 3ms.
-+ */
-+static const u32 bbr_tso_rtt_shift = 9;
-+
-+/* Pace at ~1% below estimated bw, on average, to reduce queue at bottleneck.
-+ * In order to help drive the network toward lower queues and low latency while
-+ * maintaining high utilization, the average pacing rate aims to be slightly
-+ * lower than the estimated bandwidth. This is an important aspect of the
-+ * design.
-+ */
-+static const int bbr_pacing_margin_percent = 1;
-+
-+/* We use a startup_pacing_gain of 4*ln(2) because it's the smallest value
-+ * that will allow a smoothly increasing pacing rate that will double each RTT
-+ * and send the same number of packets per RTT that an un-paced, slow-starting
-+ * Reno or CUBIC flow would:
-+ */
-+static const int bbr_startup_pacing_gain = BBR_UNIT * 277 / 100 + 1;
-+/* The gain for deriving startup cwnd: */
-+static const int bbr_startup_cwnd_gain = BBR_UNIT * 2;
-+/* The pacing gain in BBR_DRAIN is calculated to typically drain
-+ * the queue created in BBR_STARTUP in a single round:
-+ */
-+static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885;
-+/* The gain for deriving steady-state cwnd tolerates delayed/stretched ACKs: */
-+static const int bbr_cwnd_gain  = BBR_UNIT * 2;
-+/* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw: */
-+static const int bbr_pacing_gain[] = {
-+	BBR_UNIT * 5 / 4,	/* UP: probe for more available bw */
-+	BBR_UNIT * 91 / 100,	/* DOWN: drain queue and/or yield bw */
-+	BBR_UNIT,		/* CRUISE: try to use pipe w/ some headroom */
-+	BBR_UNIT,		/* REFILL: refill pipe to estimated 100% */
-+};
-+enum bbr_pacing_gain_phase {
-+	BBR_BW_PROBE_UP		= 0,  /* push up inflight to probe for bw/vol */
-+	BBR_BW_PROBE_DOWN	= 1,  /* drain excess inflight from the queue */
-+	BBR_BW_PROBE_CRUISE	= 2,  /* use pipe, w/ headroom in queue/pipe */
-+	BBR_BW_PROBE_REFILL	= 3,  /* refill the pipe again to 100% */
-+};
-+
-+/* Try to keep at least this many packets in flight, if things go smoothly. For
-+ * smooth functioning, a sliding window protocol ACKing every other packet
-+ * needs at least 4 packets in flight:
-+ */
-+static const u32 bbr_cwnd_min_target = 4;
-+
-+/* To estimate if BBR_STARTUP or BBR_BW_PROBE_UP has filled pipe... */
-+/* If bw has increased significantly (1.25x), there may be more bw available: */
-+static const u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4;
-+/* But after 3 rounds w/o significant bw growth, estimate pipe is full: */
-+static const u32 bbr_full_bw_cnt = 3;
-+
-+/* Gain factor for adding extra_acked to target cwnd: */
-+static const int bbr_extra_acked_gain = BBR_UNIT;
-+/* Window length of extra_acked window. */
-+static const u32 bbr_extra_acked_win_rtts = 5;
-+/* Max allowed val for ack_epoch_acked, after which sampling epoch is reset */
-+static const u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20;
-+/* Time period for clamping cwnd increment due to ack aggregation */
-+static const u32 bbr_extra_acked_max_us = 100 * 1000;
-+
-+/* Flags to control BBR ECN-related behavior... */
-+
-+/* Ensure ACKs only ACK packets with consistent ECN CE status? */
-+static const bool bbr_precise_ece_ack = true;
-+
-+/* Max RTT (in usec) at which to use sender-side ECN logic.
-+ * Disabled when 0 (ECN allowed at any RTT).
-+ */
-+static const u32 bbr_ecn_max_rtt_us = 5000;
-+
-+/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE.
-+ * No loss response when 0.
-+ */
-+static const u32 bbr_beta = BBR_UNIT * 30 / 100;
-+
-+/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE (1/16 = 6.25%) */
-+static const u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16;
-+
-+/* The initial value for ecn_alpha; 1.0 allows a flow to respond quickly
-+ * to congestion if the bottleneck is congested when the flow starts up.
-+ */
-+static const u32 bbr_ecn_alpha_init = BBR_UNIT;
-+
-+/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE.
-+ * No ECN based bounding when 0.
-+ */
-+static const u32 bbr_ecn_factor = BBR_UNIT * 1 / 3;	 /* 1/3 = 33% */
-+
-+/* Estimate bw probing has gone too far if CE ratio exceeds this threshold.
-+ * Scaled by BBR_SCALE. Disabled when 0.
-+ */
-+static const u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2;  /* 1/2 = 50% */
-+
-+/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN
-+ * clears then make the first round's increment to inflight_hi the following
-+ * fraction of inflight_hi.
-+ */
-+static const u32 bbr_ecn_reprobe_gain = BBR_UNIT * 1 / 2;
-+
-+/* Estimate bw probing has gone too far if loss rate exceeds this level. */
-+static const u32 bbr_loss_thresh = BBR_UNIT * 2 / 100;  /* 2% loss */
-+
-+/* Slow down for a packet loss recovered by TLP? */
-+static const bool bbr_loss_probe_recovery = true;
-+
-+/* Exit STARTUP if number of loss marking events in a Recovery round is >= N,
-+ * and loss rate is higher than bbr_loss_thresh.
-+ * Disabled if 0.
-+ */
-+static const u32 bbr_full_loss_cnt = 6;
-+
-+/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh
-+ * meets this count.
-+ */
-+static const u32 bbr_full_ecn_cnt = 2;
-+
-+/* Fraction of unutilized headroom to try to leave in path upon high loss. */
-+static const u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100;
-+
-+/* How much do we increase cwnd_gain when probing for bandwidth in
-+ * BBR_BW_PROBE_UP? This specifies the increment in units of
-+ * BBR_UNIT/4. The default is 1, meaning 0.25.
-+ * The min value is 0 (meaning 0.0); max is 3 (meaning 0.75).
-+ */
-+static const u32 bbr_bw_probe_cwnd_gain = 1;
-+
-+/* Max number of packet-timed rounds to wait before probing for bandwidth.  If
-+ * we want to tolerate 1% random loss per round, and not have this cut our
-+ * inflight too much, we must probe for bw periodically on roughly this scale.
-+ * If low, limits Reno/CUBIC coexistence; if high, limits loss tolerance.
-+ * We aim to be fair with Reno/CUBIC up to a BDP of at least:
-+ *  BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets
-+ */
-+static const u32 bbr_bw_probe_max_rounds = 63;
-+
-+/* Max amount of randomness to inject in round counting for Reno-coexistence.
-+ */
-+static const u32 bbr_bw_probe_rand_rounds = 2;
-+
-+/* Use BBR-native probe time scale starting at this many usec.
-+ * We aim to be fair with Reno/CUBIC up to an inter-loss time epoch of at least:
-+ *  BDP*RTT = 25Mbps * .030sec /(1514bytes) * 0.030sec = 1.9 secs
-+ */
-+static const u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC;  /* 2 secs */
-+
-+/* Use BBR-native probes spread over this many usec: */
-+static const u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC;  /* 1 secs */
-+
-+/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */
-+static const bool bbr_fast_path = true;
-+
-+/* Use fast ack mode? */
-+static const bool bbr_fast_ack_mode = true;
-+
-+static u32 bbr_max_bw(const struct sock *sk);
-+static u32 bbr_bw(const struct sock *sk);
-+static void bbr_exit_probe_rtt(struct sock *sk);
-+static void bbr_reset_congestion_signals(struct sock *sk);
-+static void bbr_run_loss_probe_recovery(struct sock *sk);
-+
-+static void bbr_check_probe_rtt_done(struct sock *sk);
-+
-+/* This connection can use ECN if both endpoints have signaled ECN support in
-+ * the handshake and the per-route settings indicated this is a
-+ * shallow-threshold ECN environment, meaning both:
-+ *  (a) ECN CE marks indicate low-latency/shallow-threshold congestion, and
-+ *  (b) TCP endpoints provide precise ACKs that only ACK data segments
-+ *      with consistent ECN CE status
-+ */
-+static bool bbr_can_use_ecn(const struct sock *sk)
-+{
-+	return (tcp_sk(sk)->ecn_flags & TCP_ECN_OK) &&
-+	       (tcp_sk(sk)->ecn_flags & TCP_ECN_LOW);
-+}
-+
-+/* Do we estimate that STARTUP filled the pipe? */
-+static bool bbr_full_bw_reached(const struct sock *sk)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return bbr->full_bw_reached;
-+}
-+
-+/* Return the windowed max recent bandwidth sample, in pkts/uS << BW_SCALE. */
-+static u32 bbr_max_bw(const struct sock *sk)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return max(bbr->bw_hi[0], bbr->bw_hi[1]);
-+}
-+
-+/* Return the estimated bandwidth of the path, in pkts/uS << BW_SCALE. */
-+static u32 bbr_bw(const struct sock *sk)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return min(bbr_max_bw(sk), bbr->bw_lo);
-+}
-+
-+/* Return maximum extra acked in past k-2k round trips,
-+ * where k = bbr_extra_acked_win_rtts.
-+ */
-+static u16 bbr_extra_acked(const struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return max(bbr->extra_acked[0], bbr->extra_acked[1]);
-+}
-+
-+/* Return rate in bytes per second, optionally with a gain.
-+ * The order here is chosen carefully to avoid overflow of u64. This should
-+ * work for input rates of up to 2.9Tbit/sec and gain of 2.89x.
-+ */
-+static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain,
-+				  int margin)
-+{
-+	unsigned int mss = tcp_sk(sk)->mss_cache;
-+
-+	rate *= mss;
-+	rate *= gain;
-+	rate >>= BBR_SCALE;
-+	rate *= USEC_PER_SEC / 100 * (100 - margin);
-+	rate >>= BW_SCALE;
-+	rate = max(rate, 1ULL);
-+	return rate;
-+}
-+
-+static u64 bbr_bw_bytes_per_sec(struct sock *sk, u64 rate)
-+{
-+	return bbr_rate_bytes_per_sec(sk, rate, BBR_UNIT, 0);
-+}
-+
-+/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */
-+static unsigned long bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain)
-+{
-+	u64 rate = bw;
-+
-+	rate = bbr_rate_bytes_per_sec(sk, rate, gain,
-+				      bbr_pacing_margin_percent);
-+	rate = min_t(u64, rate, READ_ONCE(sk->sk_max_pacing_rate));
-+	return rate;
-+}
-+
-+/* Initialize pacing rate to: startup_pacing_gain * init_cwnd / RTT. */
-+static void bbr_init_pacing_rate_from_rtt(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u64 bw;
-+	u32 rtt_us;
-+
-+	if (tp->srtt_us) {		/* any RTT sample yet? */
-+		rtt_us = max(tp->srtt_us >> 3, 1U);
-+		bbr->has_seen_rtt = 1;
-+	} else {			 /* no RTT sample yet */
-+		rtt_us = USEC_PER_MSEC;	 /* use nominal default RTT */
-+	}
-+	bw = (u64)tcp_snd_cwnd(tp) * BW_UNIT;
-+	do_div(bw, rtt_us);
-+	WRITE_ONCE(sk->sk_pacing_rate,
-+		   bbr_bw_to_pacing_rate(sk, bw,
-+					 bbr_param(sk, startup_pacing_gain)));
-+}
-+
-+/* Pace using current bw estimate and a gain factor. */
-+static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	unsigned long rate = bbr_bw_to_pacing_rate(sk, bw, gain);
-+
-+	if (unlikely(!bbr->has_seen_rtt && tp->srtt_us))
-+		bbr_init_pacing_rate_from_rtt(sk);
-+	if (bbr_full_bw_reached(sk) || rate > READ_ONCE(sk->sk_pacing_rate))
-+		WRITE_ONCE(sk->sk_pacing_rate, rate);
-+}
-+
-+/* Return the number of segments BBR would like in a TSO/GSO skb, given a
-+ * particular max gso size as a constraint. TODO: make this simpler and more
-+ * consistent by switching bbr to just call tcp_tso_autosize().
-+ */
-+static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now,
-+				u32 gso_max_size)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 segs, r;
-+	u64 bytes;
-+
-+	/* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */
-+	bytes = READ_ONCE(sk->sk_pacing_rate) >> READ_ONCE(sk->sk_pacing_shift);
-+
-+	/* Budget a TSO/GSO burst size allowance based on min_rtt. For every
-+	 * K = 2^tso_rtt_shift microseconds of min_rtt, halve the burst.
-+	 * The min_rtt-based burst allowance is: 64 KBytes / 2^(min_rtt/K)
-+	 */
-+	if (bbr_param(sk, tso_rtt_shift)) {
-+		r = bbr->min_rtt_us >> bbr_param(sk, tso_rtt_shift);
-+		if (r < BITS_PER_TYPE(u32))   /* prevent undefined behavior */
-+			bytes += GSO_LEGACY_MAX_SIZE >> r;
-+	}
-+
-+	bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER);
-+	segs = max_t(u32, bytes / mss_now,
-+		     sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs);
-+	return segs;
-+}
-+
-+/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */
-+__bpf_kfunc static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now)
-+{
-+	return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size);
-+}
-+
-+/* Like bbr_tso_segs(), using mss_cache, ignoring driver's sk_gso_max_size. */
-+static u32 bbr_tso_segs_goal(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+
-+	return  bbr_tso_segs_generic(sk, tp->mss_cache, GSO_LEGACY_MAX_SIZE);
-+}
-+
-+/* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */
-+static void bbr_save_cwnd(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->prev_ca_state < TCP_CA_Recovery && bbr->mode != BBR_PROBE_RTT)
-+		bbr->prior_cwnd = tcp_snd_cwnd(tp);  /* this cwnd is good enough */
-+	else  /* loss recovery or BBR_PROBE_RTT have temporarily cut cwnd */
-+		bbr->prior_cwnd = max(bbr->prior_cwnd, tcp_snd_cwnd(tp));
-+}
-+
-+__bpf_kfunc static void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (event == CA_EVENT_TX_START) {
-+		if (!tp->app_limited)
-+			return;
-+		bbr->idle_restart = 1;
-+		bbr->ack_epoch_mstamp = tp->tcp_mstamp;
-+		bbr->ack_epoch_acked = 0;
-+		/* Avoid pointless buffer overflows: pace at est. bw if we don't
-+		 * need more speed (we're restarting from idle and app-limited).
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW)
-+			bbr_set_pacing_rate(sk, bbr_bw(sk), BBR_UNIT);
-+		else if (bbr->mode == BBR_PROBE_RTT)
-+			bbr_check_probe_rtt_done(sk);
-+	} else if ((event == CA_EVENT_ECN_IS_CE ||
-+		    event == CA_EVENT_ECN_NO_CE) &&
-+		   bbr_can_use_ecn(sk) &&
-+		   bbr_param(sk, precise_ece_ack)) {
-+		u32 state = bbr->ce_state;
-+		dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state);
-+		bbr->ce_state = state;
-+	} else if (event == CA_EVENT_TLP_RECOVERY &&
-+		   bbr_param(sk, loss_probe_recovery)) {
-+		bbr_run_loss_probe_recovery(sk);
-+	}
-+}
-+
-+/* Calculate bdp based on min RTT and the estimated bottleneck bandwidth:
-+ *
-+ * bdp = ceil(bw * min_rtt * gain)
-+ *
-+ * The key factor, gain, controls the amount of queue. While a small gain
-+ * builds a smaller queue, it becomes more vulnerable to noise in RTT
-+ * measurements (e.g., delayed ACKs or other ACK compression effects). This
-+ * noise may cause BBR to under-estimate the rate.
-+ */
-+static u32 bbr_bdp(struct sock *sk, u32 bw, int gain)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bdp;
-+	u64 w;
-+
-+	/* If we've never had a valid RTT sample, cap cwnd at the initial
-+	 * default. This should only happen when the connection is not using TCP
-+	 * timestamps and has retransmitted all of the SYN/SYNACK/data packets
-+	 * ACKed so far. In this case, an RTO can cut cwnd to 1, in which
-+	 * case we need to slow-start up toward something safe: initial cwnd.
-+	 */
-+	if (unlikely(bbr->min_rtt_us == ~0U))	 /* no valid RTT samples yet? */
-+		return bbr->init_cwnd;  /* be safe: cap at initial cwnd */
-+
-+	w = (u64)bw * bbr->min_rtt_us;
-+
-+	/* Apply a gain to the given value, remove the BW_SCALE shift, and
-+	 * round the value up to avoid a negative feedback loop.
-+	 */
-+	bdp = (((w * gain) >> BBR_SCALE) + BW_UNIT - 1) / BW_UNIT;
-+
-+	return bdp;
-+}
-+
-+/* To achieve full performance in high-speed paths, we budget enough cwnd to
-+ * fit full-sized skbs in-flight on both end hosts to fully utilize the path:
-+ *   - one skb in sending host Qdisc,
-+ *   - one skb in sending host TSO/GSO engine
-+ *   - one skb being received by receiver host LRO/GRO/delayed-ACK engine
-+ * Don't worry, at low rates this won't bloat cwnd because
-+ * in such cases tso_segs_goal is small. The minimum cwnd is 4 packets,
-+ * which allows 2 outstanding 2-packet sequences, to try to keep pipe
-+ * full even with ACK-every-other-packet delayed ACKs.
-+ */
-+static u32 bbr_quantization_budget(struct sock *sk, u32 cwnd)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 tso_segs_goal;
-+
-+	tso_segs_goal = 3 * bbr_tso_segs_goal(sk);
-+
-+	/* Allow enough full-sized skbs in flight to utilize end systems. */
-+	cwnd = max_t(u32, cwnd, tso_segs_goal);
-+	cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target));
-+	/* Ensure gain cycling gets inflight above BDP even for small BDPs. */
-+	if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP)
-+		cwnd += 2;
-+
-+	return cwnd;
-+}
-+
-+/* Find inflight based on min RTT and the estimated bottleneck bandwidth. */
-+static u32 bbr_inflight(struct sock *sk, u32 bw, int gain)
-+{
-+	u32 inflight;
-+
-+	inflight = bbr_bdp(sk, bw, gain);
-+	inflight = bbr_quantization_budget(sk, inflight);
-+
-+	return inflight;
-+}
-+
-+/* With pacing at lower layers, there's often less data "in the network" than
-+ * "in flight". With TSQ and departure time pacing at lower layers (e.g. fq),
-+ * we often have several skbs queued in the pacing layer with a pre-scheduled
-+ * earliest departure time (EDT). BBR adapts its pacing rate based on the
-+ * inflight level that it estimates has already been "baked in" by previous
-+ * departure time decisions. We calculate a rough estimate of the number of our
-+ * packets that might be in the network at the earliest departure time for the
-+ * next skb scheduled:
-+ *   in_network_at_edt = inflight_at_edt - (EDT - now) * bw
-+ * If we're increasing inflight, then we want to know if the transmit of the
-+ * EDT skb will push inflight above the target, so inflight_at_edt includes
-+ * bbr_tso_segs_goal() from the skb departing at EDT. If decreasing inflight,
-+ * then estimate if inflight will sink too low just before the EDT transmit.
-+ */
-+static u32 bbr_packets_in_net_at_edt(struct sock *sk, u32 inflight_now)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u64 now_ns, edt_ns, interval_us;
-+	u32 interval_delivered, inflight_at_edt;
-+
-+	now_ns = tp->tcp_clock_cache;
-+	edt_ns = max(tp->tcp_wstamp_ns, now_ns);
-+	interval_us = div_u64(edt_ns - now_ns, NSEC_PER_USEC);
-+	interval_delivered = (u64)bbr_bw(sk) * interval_us >> BW_SCALE;
-+	inflight_at_edt = inflight_now;
-+	if (bbr->pacing_gain > BBR_UNIT)              /* increasing inflight */
-+		inflight_at_edt += bbr_tso_segs_goal(sk);  /* include EDT skb */
-+	if (interval_delivered >= inflight_at_edt)
-+		return 0;
-+	return inflight_at_edt - interval_delivered;
-+}
-+
-+/* Find the cwnd increment based on estimate of ack aggregation */
-+static u32 bbr_ack_aggregation_cwnd(struct sock *sk)
-+{
-+	u32 max_aggr_cwnd, aggr_cwnd = 0;
-+
-+	if (bbr_param(sk, extra_acked_gain)) {
-+		max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us)
-+				/ BW_UNIT;
-+		aggr_cwnd = (bbr_param(sk, extra_acked_gain) * bbr_extra_acked(sk))
-+			     >> BBR_SCALE;
-+		aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd);
-+	}
-+
-+	return aggr_cwnd;
-+}
-+
-+/* Returns the cwnd for PROBE_RTT mode. */
-+static u32 bbr_probe_rtt_cwnd(struct sock *sk)
-+{
-+	return max_t(u32, bbr_param(sk, cwnd_min_target),
-+		     bbr_bdp(sk, bbr_bw(sk), bbr_param(sk, probe_rtt_cwnd_gain)));
-+}
-+
-+/* Slow-start up toward target cwnd (if bw estimate is growing, or packet loss
-+ * has drawn us down below target), or snap down to target if we're above it.
-+ */
-+static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs,
-+			 u32 acked, u32 bw, int gain, u32 cwnd,
-+			 struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 target_cwnd = 0;
-+
-+	if (!acked)
-+		goto done;  /* no packet fully ACKed; just apply caps */
-+
-+	target_cwnd = bbr_bdp(sk, bw, gain);
-+
-+	/* Increment the cwnd to account for excess ACKed data that seems
-+	 * due to aggregation (of data and/or ACKs) visible in the ACK stream.
-+	 */
-+	target_cwnd += bbr_ack_aggregation_cwnd(sk);
-+	target_cwnd = bbr_quantization_budget(sk, target_cwnd);
-+
-+	/* Update cwnd and enable fast path if cwnd reaches target_cwnd. */
-+	bbr->try_fast_path = 0;
-+	if (bbr_full_bw_reached(sk)) { /* only cut cwnd if we filled the pipe */
-+		cwnd += acked;
-+		if (cwnd >= target_cwnd) {
-+			cwnd = target_cwnd;
-+			bbr->try_fast_path = 1;
-+		}
-+	} else if (cwnd < target_cwnd || cwnd  < 2 * bbr->init_cwnd) {
-+		cwnd += acked;
-+	} else {
-+		bbr->try_fast_path = 1;
-+	}
-+
-+	cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target));
-+done:
-+	tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp));  /* global cap */
-+	if (bbr->mode == BBR_PROBE_RTT)  /* drain queue, refresh min_rtt */
-+		tcp_snd_cwnd_set(tp, min_t(u32, tcp_snd_cwnd(tp),
-+					   bbr_probe_rtt_cwnd(sk)));
-+}
-+
-+static void bbr_reset_startup_mode(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->mode = BBR_STARTUP;
-+}
-+
-+/* See if we have reached next round trip. Upon start of the new round,
-+ * returns packets delivered since previous round start plus this ACK.
-+ */
-+static u32 bbr_update_round_start(struct sock *sk,
-+		const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 round_delivered = 0;
-+
-+	bbr->round_start = 0;
-+
-+	/* See if we've reached the next RTT */
-+	if (rs->interval_us > 0 &&
-+	    !before(rs->prior_delivered, bbr->next_rtt_delivered)) {
-+		round_delivered = tp->delivered - bbr->next_rtt_delivered;
-+		bbr->next_rtt_delivered = tp->delivered;
-+		bbr->round_start = 1;
-+	}
-+	return round_delivered;
-+}
-+
-+/* Calculate the bandwidth based on how fast packets are delivered */
-+static void bbr_calculate_bw_sample(struct sock *sk,
-+			const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	u64 bw = 0;
-+
-+	/* Divide delivered by the interval to find a (lower bound) bottleneck
-+	 * bandwidth sample. Delivered is in packets and interval_us in uS and
-+	 * ratio will be <<1 for most connections. So delivered is first scaled.
-+	 * Round up to allow growth at low rates, even with integer division.
-+	 */
-+	if (rs->interval_us > 0) {
-+		if (WARN_ONCE(rs->delivered < 0,
-+			      "negative delivered: %d interval_us: %ld\n",
-+			      rs->delivered, rs->interval_us))
-+			return;
-+
-+		bw = DIV_ROUND_UP_ULL((u64)rs->delivered * BW_UNIT, rs->interval_us);
-+	}
-+
-+	ctx->sample_bw = bw;
-+}
-+
-+/* Estimates the windowed max degree of ack aggregation.
-+ * This is used to provision extra in-flight data to keep sending during
-+ * inter-ACK silences.
-+ *
-+ * Degree of ack aggregation is estimated as extra data acked beyond expected.
-+ *
-+ * max_extra_acked = "maximum recent excess data ACKed beyond max_bw * interval"
-+ * cwnd += max_extra_acked
-+ *
-+ * Max extra_acked is clamped by cwnd and bw * bbr_extra_acked_max_us (100 ms).
-+ * Max filter is an approximate sliding window of 5-10 (packet timed) round
-+ * trips for non-startup phase, and 1-2 round trips for startup.
-+ */
-+static void bbr_update_ack_aggregation(struct sock *sk,
-+				       const struct rate_sample *rs)
-+{
-+	u32 epoch_us, expected_acked, extra_acked;
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	u32 extra_acked_win_rtts_thresh = bbr_param(sk, extra_acked_win_rtts);
-+
-+	if (!bbr_param(sk, extra_acked_gain) || rs->acked_sacked <= 0 ||
-+	    rs->delivered < 0 || rs->interval_us <= 0)
-+		return;
-+
-+	if (bbr->round_start) {
-+		bbr->extra_acked_win_rtts = min(0x1F,
-+						bbr->extra_acked_win_rtts + 1);
-+		if (!bbr_full_bw_reached(sk))
-+			extra_acked_win_rtts_thresh = 1;
-+		if (bbr->extra_acked_win_rtts >=
-+		    extra_acked_win_rtts_thresh) {
-+			bbr->extra_acked_win_rtts = 0;
-+			bbr->extra_acked_win_idx = bbr->extra_acked_win_idx ?
-+						   0 : 1;
-+			bbr->extra_acked[bbr->extra_acked_win_idx] = 0;
-+		}
-+	}
-+
-+	/* Compute how many packets we expected to be delivered over epoch. */
-+	epoch_us = tcp_stamp_us_delta(tp->delivered_mstamp,
-+				      bbr->ack_epoch_mstamp);
-+	expected_acked = ((u64)bbr_bw(sk) * epoch_us) / BW_UNIT;
-+
-+	/* Reset the aggregation epoch if ACK rate is below expected rate or
-+	 * significantly large no. of ack received since epoch (potentially
-+	 * quite old epoch).
-+	 */
-+	if (bbr->ack_epoch_acked <= expected_acked ||
-+	    (bbr->ack_epoch_acked + rs->acked_sacked >=
-+	     bbr_ack_epoch_acked_reset_thresh)) {
-+		bbr->ack_epoch_acked = 0;
-+		bbr->ack_epoch_mstamp = tp->delivered_mstamp;
-+		expected_acked = 0;
-+	}
-+
-+	/* Compute excess data delivered, beyond what was expected. */
-+	bbr->ack_epoch_acked = min_t(u32, 0xFFFFF,
-+				     bbr->ack_epoch_acked + rs->acked_sacked);
-+	extra_acked = bbr->ack_epoch_acked - expected_acked;
-+	extra_acked = min(extra_acked, tcp_snd_cwnd(tp));
-+	if (extra_acked > bbr->extra_acked[bbr->extra_acked_win_idx])
-+		bbr->extra_acked[bbr->extra_acked_win_idx] = extra_acked;
-+}
-+
-+static void bbr_check_probe_rtt_done(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (!(bbr->probe_rtt_done_stamp &&
-+	      after(tcp_jiffies32, bbr->probe_rtt_done_stamp)))
-+		return;
-+
-+	bbr->probe_rtt_min_stamp = tcp_jiffies32; /* schedule next PROBE_RTT */
-+	tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd));
-+	bbr_exit_probe_rtt(sk);
-+}
-+
-+/* The goal of PROBE_RTT mode is to have BBR flows cooperatively and
-+ * periodically drain the bottleneck queue, to converge to measure the true
-+ * min_rtt (unloaded propagation delay). This allows the flows to keep queues
-+ * small (reducing queuing delay and packet loss) and achieve fairness among
-+ * BBR flows.
-+ *
-+ * The min_rtt filter window is 10 seconds. When the min_rtt estimate expires,
-+ * we enter PROBE_RTT mode and cap the cwnd at bbr_cwnd_min_target=4 packets.
-+ * After at least bbr_probe_rtt_mode_ms=200ms and at least one packet-timed
-+ * round trip elapsed with that flight size <= 4, we leave PROBE_RTT mode and
-+ * re-enter the previous mode. BBR uses 200ms to approximately bound the
-+ * performance penalty of PROBE_RTT's cwnd capping to roughly 2% (200ms/10s).
-+ *
-+ * Note that flows need only pay 2% if they are busy sending over the last 10
-+ * seconds. Interactive applications (e.g., Web, RPCs, video chunks) often have
-+ * natural silences or low-rate periods within 10 seconds where the rate is low
-+ * enough for long enough to drain its queue in the bottleneck. We pick up
-+ * these min RTT measurements opportunistically with our min_rtt filter. :-)
-+ */
-+static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	bool probe_rtt_expired, min_rtt_expired;
-+	u32 expire;
-+
-+	/* Track min RTT in probe_rtt_win_ms to time next PROBE_RTT state. */
-+	expire = bbr->probe_rtt_min_stamp +
-+		 msecs_to_jiffies(bbr_param(sk, probe_rtt_win_ms));
-+	probe_rtt_expired = after(tcp_jiffies32, expire);
-+	if (rs->rtt_us >= 0 &&
-+	    (rs->rtt_us < bbr->probe_rtt_min_us ||
-+	     (probe_rtt_expired && !rs->is_ack_delayed))) {
-+		bbr->probe_rtt_min_us = rs->rtt_us;
-+		bbr->probe_rtt_min_stamp = tcp_jiffies32;
-+	}
-+	/* Track min RTT seen in the min_rtt_win_sec filter window: */
-+	expire = bbr->min_rtt_stamp + bbr_param(sk, min_rtt_win_sec) * HZ;
-+	min_rtt_expired = after(tcp_jiffies32, expire);
-+	if (bbr->probe_rtt_min_us <= bbr->min_rtt_us ||
-+	    min_rtt_expired) {
-+		bbr->min_rtt_us = bbr->probe_rtt_min_us;
-+		bbr->min_rtt_stamp = bbr->probe_rtt_min_stamp;
-+	}
-+
-+	if (bbr_param(sk, probe_rtt_mode_ms) > 0 && probe_rtt_expired &&
-+	    !bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) {
-+		bbr->mode = BBR_PROBE_RTT;  /* dip, drain queue */
-+		bbr_save_cwnd(sk);  /* note cwnd so we can restore it */
-+		bbr->probe_rtt_done_stamp = 0;
-+		bbr->ack_phase = BBR_ACKS_PROBE_STOPPING;
-+		bbr->next_rtt_delivered = tp->delivered;
-+	}
-+
-+	if (bbr->mode == BBR_PROBE_RTT) {
-+		/* Ignore low rate samples during this mode. */
-+		tp->app_limited =
-+			(tp->delivered + tcp_packets_in_flight(tp)) ? : 1;
-+		/* Maintain min packets in flight for max(200 ms, 1 round). */
-+		if (!bbr->probe_rtt_done_stamp &&
-+		    tcp_packets_in_flight(tp) <= bbr_probe_rtt_cwnd(sk)) {
-+			bbr->probe_rtt_done_stamp = tcp_jiffies32 +
-+				msecs_to_jiffies(bbr_param(sk, probe_rtt_mode_ms));
-+			bbr->probe_rtt_round_done = 0;
-+			bbr->next_rtt_delivered = tp->delivered;
-+		} else if (bbr->probe_rtt_done_stamp) {
-+			if (bbr->round_start)
-+				bbr->probe_rtt_round_done = 1;
-+			if (bbr->probe_rtt_round_done)
-+				bbr_check_probe_rtt_done(sk);
-+		}
-+	}
-+	/* Restart after idle ends only once we process a new S/ACK for data */
-+	if (rs->delivered > 0)
-+		bbr->idle_restart = 0;
-+}
-+
-+static void bbr_update_gains(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	switch (bbr->mode) {
-+	case BBR_STARTUP:
-+		bbr->pacing_gain = bbr_param(sk, startup_pacing_gain);
-+		bbr->cwnd_gain	 = bbr_param(sk, startup_cwnd_gain);
-+		break;
-+	case BBR_DRAIN:
-+		bbr->pacing_gain = bbr_param(sk, drain_gain);  /* slow, to drain */
-+		bbr->cwnd_gain	 = bbr_param(sk, startup_cwnd_gain);  /* keep cwnd */
-+		break;
-+	case BBR_PROBE_BW:
-+		bbr->pacing_gain = bbr_pacing_gain[bbr->cycle_idx];
-+		bbr->cwnd_gain	 = bbr_param(sk, cwnd_gain);
-+		if (bbr_param(sk, bw_probe_cwnd_gain) &&
-+		    bbr->cycle_idx == BBR_BW_PROBE_UP)
-+			bbr->cwnd_gain +=
-+				BBR_UNIT * bbr_param(sk, bw_probe_cwnd_gain) / 4;
-+		break;
-+	case BBR_PROBE_RTT:
-+		bbr->pacing_gain = BBR_UNIT;
-+		bbr->cwnd_gain	 = BBR_UNIT;
-+		break;
-+	default:
-+		WARN_ONCE(1, "BBR bad mode: %u\n", bbr->mode);
-+		break;
-+	}
-+}
-+
-+__bpf_kfunc static u32 bbr_sndbuf_expand(struct sock *sk)
-+{
-+	/* Provision 3 * cwnd since BBR may slow-start even during recovery. */
-+	return 3;
-+}
-+
-+/* Incorporate a new bw sample into the current window of our max filter. */
-+static void bbr_take_max_bw_sample(struct sock *sk, u32 bw)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->bw_hi[1] = max(bw, bbr->bw_hi[1]);
-+}
-+
-+/* Keep max of last 1-2 cycles. Each PROBE_BW cycle, flip filter window. */
-+static void bbr_advance_max_bw_filter(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (!bbr->bw_hi[1])
-+		return;  /* no samples in this window; remember old window */
-+	bbr->bw_hi[0] = bbr->bw_hi[1];
-+	bbr->bw_hi[1] = 0;
-+}
-+
-+/* Reset the estimator for reaching full bandwidth based on bw plateau. */
-+static void bbr_reset_full_bw(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->full_bw = 0;
-+	bbr->full_bw_cnt = 0;
-+	bbr->full_bw_now = 0;
-+}
-+
-+/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */
-+static u32 bbr_target_inflight(struct sock *sk)
-+{
-+	u32 bdp = bbr_inflight(sk, bbr_bw(sk), BBR_UNIT);
-+
-+	return min(bdp, tcp_sk(sk)->snd_cwnd);
-+}
-+
-+static bool bbr_is_probing_bandwidth(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return (bbr->mode == BBR_STARTUP) ||
-+		(bbr->mode == BBR_PROBE_BW &&
-+		 (bbr->cycle_idx == BBR_BW_PROBE_REFILL ||
-+		  bbr->cycle_idx == BBR_BW_PROBE_UP));
-+}
-+
-+/* Has the given amount of time elapsed since we marked the phase start? */
-+static bool bbr_has_elapsed_in_phase(const struct sock *sk, u32 interval_us)
-+{
-+	const struct tcp_sock *tp = tcp_sk(sk);
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return tcp_stamp_us_delta(tp->tcp_mstamp,
-+				  bbr->cycle_mstamp + interval_us) > 0;
-+}
-+
-+static void bbr_handle_queue_too_high_in_startup(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bdp;  /* estimated BDP in packets, with quantization budget */
-+
-+	bbr->full_bw_reached = 1;
-+
-+	bdp = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+	bbr->inflight_hi = max(bdp, bbr->inflight_latest);
-+}
-+
-+/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */
-+static void bbr_check_ecn_too_high_in_startup(struct sock *sk, u32 ce_ratio)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr_full_bw_reached(sk) || !bbr->ecn_eligible ||
-+	    !bbr_param(sk, full_ecn_cnt) || !bbr_param(sk, ecn_thresh))
-+		return;
-+
-+	if (ce_ratio >= bbr_param(sk, ecn_thresh))
-+		bbr->startup_ecn_rounds++;
-+	else
-+		bbr->startup_ecn_rounds = 0;
-+
-+	if (bbr->startup_ecn_rounds >= bbr_param(sk, full_ecn_cnt)) {
-+		bbr_handle_queue_too_high_in_startup(sk);
-+		return;
-+	}
-+}
-+
-+/* Updates ecn_alpha and returns ce_ratio. -1 if not available. */
-+static int bbr_update_ecn_alpha(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct net *net = sock_net(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	s32 delivered, delivered_ce;
-+	u64 alpha, ce_ratio;
-+	u32 gain;
-+	bool want_ecn_alpha;
-+
-+	/* See if we should use ECN sender logic for this connection. */
-+	if (!bbr->ecn_eligible && bbr_can_use_ecn(sk) &&
-+	    !!bbr_param(sk, ecn_factor) &&
-+	    (bbr->min_rtt_us <= bbr_ecn_max_rtt_us ||
-+	     !bbr_ecn_max_rtt_us))
-+		bbr->ecn_eligible = 1;
-+
-+	/* Skip updating alpha only if not ECN-eligible and PLB is disabled. */
-+	want_ecn_alpha = (bbr->ecn_eligible ||
-+			  (bbr_can_use_ecn(sk) &&
-+			   READ_ONCE(net->ipv4.sysctl_tcp_plb_enabled)));
-+	if (!want_ecn_alpha)
-+		return -1;
-+
-+	delivered = tp->delivered - bbr->alpha_last_delivered;
-+	delivered_ce = tp->delivered_ce - bbr->alpha_last_delivered_ce;
-+
-+	if (delivered == 0 ||		/* avoid divide by zero */
-+	    WARN_ON_ONCE(delivered < 0 || delivered_ce < 0))  /* backwards? */
-+		return -1;
-+
-+	BUILD_BUG_ON(BBR_SCALE != TCP_PLB_SCALE);
-+	ce_ratio = (u64)delivered_ce << BBR_SCALE;
-+	do_div(ce_ratio, delivered);
-+
-+	gain = bbr_param(sk, ecn_alpha_gain);
-+	alpha = ((BBR_UNIT - gain) * bbr->ecn_alpha) >> BBR_SCALE;
-+	alpha += (gain * ce_ratio) >> BBR_SCALE;
-+	bbr->ecn_alpha = min_t(u32, alpha, BBR_UNIT);
-+
-+	bbr->alpha_last_delivered = tp->delivered;
-+	bbr->alpha_last_delivered_ce = tp->delivered_ce;
-+
-+	bbr_check_ecn_too_high_in_startup(sk, ce_ratio);
-+	return (int)ce_ratio;
-+}
-+
-+/* Protective Load Balancing (PLB). PLB rehashes outgoing data (to a new IPv6
-+ * flow label) if it encounters sustained congestion in the form of ECN marks.
-+ */
-+static void bbr_plb(struct sock *sk, const struct rate_sample *rs, int ce_ratio)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->round_start && ce_ratio >= 0)
-+		tcp_plb_update_state(sk, &bbr->plb, ce_ratio);
-+
-+	tcp_plb_check_rehash(sk, &bbr->plb);
-+}
-+
-+/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */
-+static void bbr_raise_inflight_hi_slope(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 growth_this_round, cnt;
-+
-+	/* Calculate "slope": packets S/Acked per inflight_hi increment. */
-+	growth_this_round = 1 << bbr->bw_probe_up_rounds;
-+	bbr->bw_probe_up_rounds = min(bbr->bw_probe_up_rounds + 1, 30);
-+	cnt = tcp_snd_cwnd(tp) / growth_this_round;
-+	cnt = max(cnt, 1U);
-+	bbr->bw_probe_up_cnt = cnt;
-+}
-+
-+/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */
-+static void bbr_probe_inflight_hi_upward(struct sock *sk,
-+					  const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 delta;
-+
-+	if (!tp->is_cwnd_limited || tcp_snd_cwnd(tp) < bbr->inflight_hi)
-+		return;  /* not fully using inflight_hi, so don't grow it */
-+
-+	/* For each bw_probe_up_cnt packets ACKed, increase inflight_hi by 1. */
-+	bbr->bw_probe_up_acks += rs->acked_sacked;
-+	if (bbr->bw_probe_up_acks >=  bbr->bw_probe_up_cnt) {
-+		delta = bbr->bw_probe_up_acks / bbr->bw_probe_up_cnt;
-+		bbr->bw_probe_up_acks -= delta * bbr->bw_probe_up_cnt;
-+		bbr->inflight_hi += delta;
-+		bbr->try_fast_path = 0;  /* Need to update cwnd */
-+	}
-+
-+	if (bbr->round_start)
-+		bbr_raise_inflight_hi_slope(sk);
-+}
-+
-+/* Does loss/ECN rate for this sample say inflight is "too high"?
-+ * This is used by both the bbr_check_loss_too_high_in_startup() function,
-+ * and in PROBE_UP.
-+ */
-+static bool bbr_is_inflight_too_high(const struct sock *sk,
-+				      const struct rate_sample *rs)
-+{
-+	const struct bbr *bbr = inet_csk_ca(sk);
-+	u32 loss_thresh, ecn_thresh;
-+
-+	if (rs->lost > 0 && rs->tx_in_flight) {
-+		loss_thresh = (u64)rs->tx_in_flight * bbr_param(sk, loss_thresh) >>
-+				BBR_SCALE;
-+		if (rs->lost > loss_thresh) {
-+			return true;
-+		}
-+	}
-+
-+	if (rs->delivered_ce > 0 && rs->delivered > 0 &&
-+	    bbr->ecn_eligible && !!bbr_param(sk, ecn_thresh)) {
-+		ecn_thresh = (u64)rs->delivered * bbr_param(sk, ecn_thresh) >>
-+				BBR_SCALE;
-+		if (rs->delivered_ce > ecn_thresh) {
-+			return true;
-+		}
-+	}
-+
-+	return false;
-+}
-+
-+/* Calculate the tx_in_flight level that corresponded to excessive loss.
-+ * We find "lost_prefix" segs of the skb where loss rate went too high,
-+ * by solving for "lost_prefix" in the following equation:
-+ *   lost                     /  inflight                     >= loss_thresh
-+ *  (lost_prev + lost_prefix) / (inflight_prev + lost_prefix) >= loss_thresh
-+ * Then we take that equation, convert it to fixed point, and
-+ * round up to the nearest packet.
-+ */
-+static u32 bbr_inflight_hi_from_lost_skb(const struct sock *sk,
-+					  const struct rate_sample *rs,
-+					  const struct sk_buff *skb)
-+{
-+	const struct tcp_sock *tp = tcp_sk(sk);
-+	u32 loss_thresh  = bbr_param(sk, loss_thresh);
-+	u32 pcount, divisor, inflight_hi;
-+	s32 inflight_prev, lost_prev;
-+	u64 loss_budget, lost_prefix;
-+
-+	pcount = tcp_skb_pcount(skb);
-+
-+	/* How much data was in flight before this skb? */
-+	inflight_prev = rs->tx_in_flight - pcount;
-+	if (inflight_prev < 0) {
-+		WARN_ONCE(tcp_skb_tx_in_flight_is_suspicious(
-+				  pcount,
-+				  TCP_SKB_CB(skb)->sacked,
-+				  rs->tx_in_flight),
-+			  "tx_in_flight: %u pcount: %u reneg: %u",
-+			  rs->tx_in_flight, pcount, tcp_sk(sk)->is_sack_reneg);
-+		return ~0U;
-+	}
-+
-+	/* How much inflight data was marked lost before this skb? */
-+	lost_prev = rs->lost - pcount;
-+	if (WARN_ONCE(lost_prev < 0,
-+		      "cwnd: %u ca: %d out: %u lost: %u pif: %u "
-+		      "tx_in_flight: %u tx.lost: %u tp->lost: %u rs->lost: %d "
-+		      "lost_prev: %d pcount: %d seq: %u end_seq: %u reneg: %u",
-+		      tcp_snd_cwnd(tp), inet_csk(sk)->icsk_ca_state,
-+		      tp->packets_out, tp->lost_out, tcp_packets_in_flight(tp),
-+		      rs->tx_in_flight, TCP_SKB_CB(skb)->tx.lost, tp->lost,
-+		      rs->lost, lost_prev, pcount,
-+		      TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
-+		      tp->is_sack_reneg))
-+		return ~0U;
-+
-+	/* At what prefix of this lost skb did losss rate exceed loss_thresh? */
-+	loss_budget = (u64)inflight_prev * loss_thresh + BBR_UNIT - 1;
-+	loss_budget >>= BBR_SCALE;
-+	if (lost_prev >= loss_budget) {
-+		lost_prefix = 0;   /* previous losses crossed loss_thresh */
-+	} else {
-+		lost_prefix = loss_budget - lost_prev;
-+		lost_prefix <<= BBR_SCALE;
-+		divisor = BBR_UNIT - loss_thresh;
-+		if (WARN_ON_ONCE(!divisor))  /* loss_thresh is 8 bits */
-+			return ~0U;
-+		do_div(lost_prefix, divisor);
-+	}
-+
-+	inflight_hi = inflight_prev + lost_prefix;
-+	return inflight_hi;
-+}
-+
-+/* If loss/ECN rates during probing indicated we may have overfilled a
-+ * buffer, return an operating point that tries to leave unutilized headroom in
-+ * the path for other flows, for fairness convergence and lower RTTs and loss.
-+ */
-+static u32 bbr_inflight_with_headroom(const struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 headroom, headroom_fraction;
-+
-+	if (bbr->inflight_hi == ~0U)
-+		return ~0U;
-+
-+	headroom_fraction = bbr_param(sk, inflight_headroom);
-+	headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE;
-+	headroom = max(headroom, 1U);
-+	return max_t(s32, bbr->inflight_hi - headroom,
-+		     bbr_param(sk, cwnd_min_target));
-+}
-+
-+/* Bound cwnd to a sensible level, based on our current probing state
-+ * machine phase and model of a good inflight level (inflight_lo, inflight_hi).
-+ */
-+static void bbr_bound_cwnd_for_inflight_model(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 cap;
-+
-+	/* tcp_rcv_synsent_state_process() currently calls tcp_ack()
-+	 * and thus cong_control() without first initializing us(!).
-+	 */
-+	if (!bbr->initialized)
-+		return;
-+
-+	cap = ~0U;
-+	if (bbr->mode == BBR_PROBE_BW &&
-+	    bbr->cycle_idx != BBR_BW_PROBE_CRUISE) {
-+		/* Probe to see if more packets fit in the path. */
-+		cap = bbr->inflight_hi;
-+	} else {
-+		if (bbr->mode == BBR_PROBE_RTT ||
-+		    (bbr->mode == BBR_PROBE_BW &&
-+		     bbr->cycle_idx == BBR_BW_PROBE_CRUISE))
-+			cap = bbr_inflight_with_headroom(sk);
-+	}
-+	/* Adapt to any loss/ECN since our last bw probe. */
-+	cap = min(cap, bbr->inflight_lo);
-+
-+	cap = max_t(u32, cap, bbr_param(sk, cwnd_min_target));
-+	tcp_snd_cwnd_set(tp, min(cap, tcp_snd_cwnd(tp)));
-+}
-+
-+/* How should we multiplicatively cut bw or inflight limits based on ECN? */
-+static u32 bbr_ecn_cut(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	return BBR_UNIT -
-+		((bbr->ecn_alpha * bbr_param(sk, ecn_factor)) >> BBR_SCALE);
-+}
-+
-+/* Init lower bounds if have not inited yet. */
-+static void bbr_init_lower_bounds(struct sock *sk, bool init_bw)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (init_bw && bbr->bw_lo == ~0U)
-+		bbr->bw_lo = bbr_max_bw(sk);
-+	if (bbr->inflight_lo == ~0U)
-+		bbr->inflight_lo = tcp_snd_cwnd(tp);
-+}
-+
-+/* Reduce bw and inflight to (1 - beta). */
-+static void bbr_loss_lower_bounds(struct sock *sk, u32 *bw, u32 *inflight)
-+{
-+	struct bbr* bbr = inet_csk_ca(sk);
-+	u32 loss_cut = BBR_UNIT - bbr_param(sk, beta);
-+
-+	*bw = max_t(u32, bbr->bw_latest,
-+		    (u64)bbr->bw_lo * loss_cut >> BBR_SCALE);
-+	*inflight = max_t(u32, bbr->inflight_latest,
-+			  (u64)bbr->inflight_lo * loss_cut >> BBR_SCALE);
-+}
-+
-+/* Reduce inflight to (1 - alpha*ecn_factor). */
-+static void bbr_ecn_lower_bounds(struct sock *sk, u32 *inflight)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 ecn_cut = bbr_ecn_cut(sk);
-+
-+	*inflight = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE;
-+}
-+
-+/* Estimate a short-term lower bound on the capacity available now, based
-+ * on measurements of the current delivery process and recent history. When we
-+ * are seeing loss/ECN at times when we are not probing bw, then conservatively
-+ * move toward flow balance by multiplicatively cutting our short-term
-+ * estimated safe rate and volume of data (bw_lo and inflight_lo). We use a
-+ * multiplicative decrease in order to converge to a lower capacity in time
-+ * logarithmic in the magnitude of the decrease.
-+ *
-+ * However, we do not cut our short-term estimates lower than the current rate
-+ * and volume of delivered data from this round trip, since from the current
-+ * delivery process we can estimate the measured capacity available now.
-+ *
-+ * Anything faster than that approach would knowingly risk high loss, which can
-+ * cause low bw for Reno/CUBIC and high loss recovery latency for
-+ * request/response flows using any congestion control.
-+ */
-+static void bbr_adapt_lower_bounds(struct sock *sk,
-+				    const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 ecn_inflight_lo = ~0U;
-+
-+	/* We only use lower-bound estimates when not probing bw.
-+	 * When probing we need to push inflight higher to probe bw.
-+	 */
-+	if (bbr_is_probing_bandwidth(sk))
-+		return;
-+
-+	/* ECN response. */
-+	if (bbr->ecn_in_round && !!bbr_param(sk, ecn_factor)) {
-+		bbr_init_lower_bounds(sk, false);
-+		bbr_ecn_lower_bounds(sk, &ecn_inflight_lo);
-+	}
-+
-+	/* Loss response. */
-+	if (bbr->loss_in_round) {
-+		bbr_init_lower_bounds(sk, true);
-+		bbr_loss_lower_bounds(sk, &bbr->bw_lo, &bbr->inflight_lo);
-+	}
-+
-+	/* Adjust to the lower of the levels implied by loss/ECN. */
-+	bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo);
-+	bbr->bw_lo = max(1U, bbr->bw_lo);
-+}
-+
-+/* Reset any short-term lower-bound adaptation to congestion, so that we can
-+ * push our inflight up.
-+ */
-+static void bbr_reset_lower_bounds(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->bw_lo = ~0U;
-+	bbr->inflight_lo = ~0U;
-+}
-+
-+/* After bw probing (STARTUP/PROBE_UP), reset signals before entering a state
-+ * machine phase where we adapt our lower bound based on congestion signals.
-+ */
-+static void bbr_reset_congestion_signals(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->loss_in_round = 0;
-+	bbr->ecn_in_round = 0;
-+	bbr->loss_in_cycle = 0;
-+	bbr->ecn_in_cycle = 0;
-+	bbr->bw_latest = 0;
-+	bbr->inflight_latest = 0;
-+}
-+
-+static void bbr_exit_loss_recovery(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd));
-+	bbr->try_fast_path = 0; /* bound cwnd using latest model */
-+}
-+
-+/* Update rate and volume of delivered data from latest round trip. */
-+static void bbr_update_latest_delivery_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->loss_round_start = 0;
-+	if (rs->interval_us <= 0 || !rs->acked_sacked)
-+		return; /* Not a valid observation */
-+
-+	bbr->bw_latest       = max_t(u32, bbr->bw_latest,       ctx->sample_bw);
-+	bbr->inflight_latest = max_t(u32, bbr->inflight_latest, rs->delivered);
-+
-+	if (!before(rs->prior_delivered, bbr->loss_round_delivered)) {
-+		bbr->loss_round_delivered = tp->delivered;
-+		bbr->loss_round_start = 1;  /* mark start of new round trip */
-+	}
-+}
-+
-+/* Once per round, reset filter for latest rate and volume of delivered data. */
-+static void bbr_advance_latest_delivery_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* If ACK matches a TLP retransmit, persist the filter. If we detect
-+	 * that a TLP retransmit plugged a tail loss, we'll want to remember
-+	 * how much data the path delivered before the tail loss.
-+	 */
-+	if (bbr->loss_round_start && !rs->is_acking_tlp_retrans_seq) {
-+		bbr->bw_latest = ctx->sample_bw;
-+		bbr->inflight_latest = rs->delivered;
-+	}
-+}
-+
-+/* Update (most of) our congestion signals: track the recent rate and volume of
-+ * delivered data, presence of loss, and EWMA degree of ECN marking.
-+ */
-+static void bbr_update_congestion_signals(
-+	struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u64 bw;
-+
-+	if (rs->interval_us <= 0 || !rs->acked_sacked)
-+		return; /* Not a valid observation */
-+	bw = ctx->sample_bw;
-+
-+	if (!rs->is_app_limited || bw >= bbr_max_bw(sk))
-+		bbr_take_max_bw_sample(sk, bw);
-+
-+	bbr->loss_in_round |= (rs->losses > 0);
-+
-+	if (!bbr->loss_round_start)
-+		return;		/* skip the per-round-trip updates */
-+	/* Now do per-round-trip updates. */
-+	bbr_adapt_lower_bounds(sk, rs);
-+
-+	bbr->loss_in_round = 0;
-+	bbr->ecn_in_round  = 0;
-+}
-+
-+/* Bandwidth probing can cause loss. To help coexistence with loss-based
-+ * congestion control we spread out our probing in a Reno-conscious way. Due to
-+ * the shape of the Reno sawtooth, the time required between loss epochs for an
-+ * idealized Reno flow is a number of round trips that is the BDP of that
-+ * flow. We count packet-timed round trips directly, since measured RTT can
-+ * vary widely, and Reno is driven by packet-timed round trips.
-+ */
-+static bool bbr_is_reno_coexistence_probe_time(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 rounds;
-+
-+	/* Random loss can shave some small percentage off of our inflight
-+	 * in each round. To survive this, flows need robust periodic probes.
-+	 */
-+	rounds = min_t(u32, bbr_param(sk, bw_probe_max_rounds), bbr_target_inflight(sk));
-+	return bbr->rounds_since_probe >= rounds;
-+}
-+
-+/* How long do we want to wait before probing for bandwidth (and risking
-+ * loss)? We randomize the wait, for better mixing and fairness convergence.
-+ *
-+ * We bound the Reno-coexistence inter-bw-probe time to be 62-63 round trips.
-+ * This is calculated to allow fairness with a 25Mbps, 30ms Reno flow,
-+ * (eg 4K video to a broadband user):
-+ *   BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets
-+ *
-+ * We bound the BBR-native inter-bw-probe wall clock time to be:
-+ *  (a) higher than 2 sec: to try to avoid causing loss for a long enough time
-+ *      to allow Reno at 30ms to get 4K video bw, the inter-bw-probe time must
-+ *      be at least: 25Mbps * .030sec / (1514bytes) * 0.030sec = 1.9secs
-+ *  (b) lower than 3 sec: to ensure flows can start probing in a reasonable
-+ *      amount of time to discover unutilized bw on human-scale interactive
-+ *      time-scales (e.g. perhaps traffic from a web page download that we
-+ *      were competing with is now complete).
-+ */
-+static void bbr_pick_probe_wait(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Decide the random round-trip bound for wait until probe: */
-+	bbr->rounds_since_probe =
-+		get_random_u32_below(bbr_param(sk, bw_probe_rand_rounds));
-+	/* Decide the random wall clock bound for wait until probe: */
-+	bbr->probe_wait_us = bbr_param(sk, bw_probe_base_us) +
-+			     get_random_u32_below(bbr_param(sk, bw_probe_rand_us));
-+}
-+
-+static void bbr_set_cycle_idx(struct sock *sk, int cycle_idx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->cycle_idx = cycle_idx;
-+	/* New phase, so need to update cwnd and pacing rate. */
-+	bbr->try_fast_path = 0;
-+}
-+
-+/* Send at estimated bw to fill the pipe, but not queue. We need this phase
-+ * before PROBE_UP, because as soon as we send faster than the available bw
-+ * we will start building a queue, and if the buffer is shallow we can cause
-+ * loss. If we do not fill the pipe before we cause this loss, our bw_hi and
-+ * inflight_hi estimates will underestimate.
-+ */
-+static void bbr_start_bw_probe_refill(struct sock *sk, u32 bw_probe_up_rounds)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_lower_bounds(sk);
-+	bbr->bw_probe_up_rounds = bw_probe_up_rounds;
-+	bbr->bw_probe_up_acks = 0;
-+	bbr->stopped_risky_probe = 0;
-+	bbr->ack_phase = BBR_ACKS_REFILLING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_REFILL);
-+}
-+
-+/* Now probe max deliverable data rate and volume. */
-+static void bbr_start_bw_probe_up(struct sock *sk, struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->ack_phase = BBR_ACKS_PROBE_STARTING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr->cycle_mstamp = tp->tcp_mstamp;
-+	bbr_reset_full_bw(sk);
-+	bbr->full_bw = ctx->sample_bw;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_UP);
-+	bbr_raise_inflight_hi_slope(sk);
-+}
-+
-+/* Start a new PROBE_BW probing cycle of some wall clock length. Pick a wall
-+ * clock time at which to probe beyond an inflight that we think to be
-+ * safe. This will knowingly risk packet loss, so we want to do this rarely, to
-+ * keep packet loss rates low. Also start a round-trip counter, to probe faster
-+ * if we estimate a Reno flow at our BDP would probe faster.
-+ */
-+static void bbr_start_bw_probe_down(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_congestion_signals(sk);
-+	bbr->bw_probe_up_cnt = ~0U;     /* not growing inflight_hi any more */
-+	bbr_pick_probe_wait(sk);
-+	bbr->cycle_mstamp = tp->tcp_mstamp;		/* start wall clock */
-+	bbr->ack_phase = BBR_ACKS_PROBE_STOPPING;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_DOWN);
-+}
-+
-+/* Cruise: maintain what we estimate to be a neutral, conservative
-+ * operating point, without attempting to probe up for bandwidth or down for
-+ * RTT, and only reducing inflight in response to loss/ECN signals.
-+ */
-+static void bbr_start_bw_probe_cruise(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->inflight_lo != ~0U)
-+		bbr->inflight_lo = min(bbr->inflight_lo, bbr->inflight_hi);
-+
-+	bbr_set_cycle_idx(sk, BBR_BW_PROBE_CRUISE);
-+}
-+
-+/* Loss and/or ECN rate is too high while probing.
-+ * Adapt (once per bw probe) by cutting inflight_hi and then restarting cycle.
-+ */
-+static void bbr_handle_inflight_too_high(struct sock *sk,
-+					  const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	const u32 beta = bbr_param(sk, beta);
-+
-+	bbr->prev_probe_too_high = 1;
-+	bbr->bw_probe_samples = 0;  /* only react once per probe */
-+	/* If we are app-limited then we are not robustly
-+	 * probing the max volume of inflight data we think
-+	 * might be safe (analogous to how app-limited bw
-+	 * samples are not known to be robustly probing bw).
-+	 */
-+	if (!rs->is_app_limited) {
-+		bbr->inflight_hi = max_t(u32, rs->tx_in_flight,
-+					 (u64)bbr_target_inflight(sk) *
-+					 (BBR_UNIT - beta) >> BBR_SCALE);
-+	}
-+	if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP)
-+		bbr_start_bw_probe_down(sk);
-+}
-+
-+/* If we're seeing bw and loss samples reflecting our bw probing, adapt
-+ * using the signals we see. If loss or ECN mark rate gets too high, then adapt
-+ * inflight_hi downward. If we're able to push inflight higher without such
-+ * signals, push higher: adapt inflight_hi upward.
-+ */
-+static bool bbr_adapt_upper_bounds(struct sock *sk,
-+				    const struct rate_sample *rs,
-+				    struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Track when we'll see bw/loss samples resulting from our bw probes. */
-+	if (bbr->ack_phase == BBR_ACKS_PROBE_STARTING && bbr->round_start)
-+		bbr->ack_phase = BBR_ACKS_PROBE_FEEDBACK;
-+	if (bbr->ack_phase == BBR_ACKS_PROBE_STOPPING && bbr->round_start) {
-+		/* End of samples from bw probing phase. */
-+		bbr->bw_probe_samples = 0;
-+		bbr->ack_phase = BBR_ACKS_INIT;
-+		/* At this point in the cycle, our current bw sample is also
-+		 * our best recent chance at finding the highest available bw
-+		 * for this flow. So now is the best time to forget the bw
-+		 * samples from the previous cycle, by advancing the window.
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW && !rs->is_app_limited)
-+			bbr_advance_max_bw_filter(sk);
-+		/* If we had an inflight_hi, then probed and pushed inflight all
-+		 * the way up to hit that inflight_hi without seeing any
-+		 * high loss/ECN in all the resulting ACKs from that probing,
-+		 * then probe up again, this time letting inflight persist at
-+		 * inflight_hi for a round trip, then accelerating beyond.
-+		 */
-+		if (bbr->mode == BBR_PROBE_BW &&
-+		    bbr->stopped_risky_probe && !bbr->prev_probe_too_high) {
-+			bbr_start_bw_probe_refill(sk, 0);
-+			return true;  /* yes, decided state transition */
-+		}
-+	}
-+	if (bbr_is_inflight_too_high(sk, rs)) {
-+		if (bbr->bw_probe_samples)  /*  sample is from bw probing? */
-+			bbr_handle_inflight_too_high(sk, rs);
-+	} else {
-+		/* Loss/ECN rate is declared safe. Adjust upper bound upward. */
-+
-+		if (bbr->inflight_hi == ~0U)
-+			return false;   /* no excess queue signals yet */
-+
-+		/* To be resilient to random loss, we must raise bw/inflight_hi
-+		 * if we observe in any phase that a higher level is safe.
-+		 */
-+		if (rs->tx_in_flight > bbr->inflight_hi) {
-+			bbr->inflight_hi = rs->tx_in_flight;
-+		}
-+
-+		if (bbr->mode == BBR_PROBE_BW &&
-+		    bbr->cycle_idx == BBR_BW_PROBE_UP)
-+			bbr_probe_inflight_hi_upward(sk, rs);
-+	}
-+
-+	return false;
-+}
-+
-+/* Check if it's time to probe for bandwidth now, and if so, kick it off. */
-+static bool bbr_check_time_to_probe_bw(struct sock *sk,
-+					const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 n;
-+
-+	/* If we seem to be at an operating point where we are not seeing loss
-+	 * but we are seeing ECN marks, then when the ECN marks cease we reprobe
-+	 * quickly (in case cross-traffic has ceased and freed up bw).
-+	 */
-+	if (bbr_param(sk, ecn_reprobe_gain) && bbr->ecn_eligible &&
-+	    bbr->ecn_in_cycle && !bbr->loss_in_cycle &&
-+	    inet_csk(sk)->icsk_ca_state == TCP_CA_Open) {
-+		/* Calculate n so that when bbr_raise_inflight_hi_slope()
-+		 * computes growth_this_round as 2^n it will be roughly the
-+		 * desired volume of data (inflight_hi*ecn_reprobe_gain).
-+		 */
-+		n = ilog2((((u64)bbr->inflight_hi *
-+			    bbr_param(sk, ecn_reprobe_gain)) >> BBR_SCALE));
-+		bbr_start_bw_probe_refill(sk, n);
-+		return true;
-+	}
-+
-+	if (bbr_has_elapsed_in_phase(sk, bbr->probe_wait_us) ||
-+	    bbr_is_reno_coexistence_probe_time(sk)) {
-+		bbr_start_bw_probe_refill(sk, 0);
-+		return true;
-+	}
-+	return false;
-+}
-+
-+/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */
-+static bool bbr_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw)
-+{
-+	/* Always need to pull inflight down to leave headroom in queue. */
-+	if (inflight > bbr_inflight_with_headroom(sk))
-+		return false;
-+
-+	return inflight <= bbr_inflight(sk, bw, BBR_UNIT);
-+}
-+
-+/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */
-+static void bbr_update_cycle_phase(struct sock *sk,
-+				    const struct rate_sample *rs,
-+				    struct bbr_context *ctx)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	bool is_bw_probe_done = false;
-+	u32 inflight, bw;
-+
-+	if (!bbr_full_bw_reached(sk))
-+		return;
-+
-+	/* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */
-+	if (bbr_adapt_upper_bounds(sk, rs, ctx))
-+		return;		/* already decided state transition */
-+
-+	if (bbr->mode != BBR_PROBE_BW)
-+		return;
-+
-+	inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight);
-+	bw = bbr_max_bw(sk);
-+
-+	switch (bbr->cycle_idx) {
-+	/* First we spend most of our time cruising with a pacing_gain of 1.0,
-+	 * which paces at the estimated bw, to try to fully use the pipe
-+	 * without building queue. If we encounter loss/ECN marks, we adapt
-+	 * by slowing down.
-+	 */
-+	case BBR_BW_PROBE_CRUISE:
-+		if (bbr_check_time_to_probe_bw(sk, rs))
-+			return;		/* already decided state transition */
-+		break;
-+
-+	/* After cruising, when it's time to probe, we first "refill": we send
-+	 * at the estimated bw to fill the pipe, before probing higher and
-+	 * knowingly risking overflowing the bottleneck buffer (causing loss).
-+	 */
-+	case BBR_BW_PROBE_REFILL:
-+		if (bbr->round_start) {
-+			/* After one full round trip of sending in REFILL, we
-+			 * start to see bw samples reflecting our REFILL, which
-+			 * may be putting too much data in flight.
-+			 */
-+			bbr->bw_probe_samples = 1;
-+			bbr_start_bw_probe_up(sk, ctx);
-+		}
-+		break;
-+
-+	/* After we refill the pipe, we probe by using a pacing_gain > 1.0, to
-+	 * probe for bw. If we have not seen loss/ECN, we try to raise inflight
-+	 * to at least pacing_gain*BDP; note that this may take more than
-+	 * min_rtt if min_rtt is small (e.g. on a LAN).
-+	 *
-+	 * We terminate PROBE_UP bandwidth probing upon any of the following:
-+	 *
-+	 * (1) We've pushed inflight up to hit the inflight_hi target set in the
-+	 *     most recent previous bw probe phase. Thus we want to start
-+	 *     draining the queue immediately because it's very likely the most
-+	 *     recently sent packets will fill the queue and cause drops.
-+	 * (2) If inflight_hi has not limited bandwidth growth recently, and
-+	 *     yet delivered bandwidth has not increased much recently
-+	 *     (bbr->full_bw_now).
-+	 * (3) Loss filter says loss rate is "too high".
-+	 * (4) ECN filter says ECN mark rate is "too high".
-+	 *
-+	 * (1) (2) checked here, (3) (4) checked in bbr_is_inflight_too_high()
-+	 */
-+	case BBR_BW_PROBE_UP:
-+		if (bbr->prev_probe_too_high &&
-+		    inflight >= bbr->inflight_hi) {
-+			bbr->stopped_risky_probe = 1;
-+			is_bw_probe_done = true;
-+		} else {
-+			if (tp->is_cwnd_limited &&
-+			    tcp_snd_cwnd(tp) >= bbr->inflight_hi) {
-+				/* inflight_hi is limiting bw growth */
-+				bbr_reset_full_bw(sk);
-+				bbr->full_bw = ctx->sample_bw;
-+			} else if (bbr->full_bw_now) {
-+				/* Plateau in estimated bw. Pipe looks full. */
-+				is_bw_probe_done = true;
-+			}
-+		}
-+		if (is_bw_probe_done) {
-+			bbr->prev_probe_too_high = 0;  /* no loss/ECN (yet) */
-+			bbr_start_bw_probe_down(sk);  /* restart w/ down */
-+		}
-+		break;
-+
-+	/* After probing in PROBE_UP, we have usually accumulated some data in
-+	 * the bottleneck buffer (if bw probing didn't find more bw). We next
-+	 * enter PROBE_DOWN to try to drain any excess data from the queue. To
-+	 * do this, we use a pacing_gain < 1.0. We hold this pacing gain until
-+	 * our inflight is less then that target cruising point, which is the
-+	 * minimum of (a) the amount needed to leave headroom, and (b) the
-+	 * estimated BDP. Once inflight falls to match the target, we estimate
-+	 * the queue is drained; persisting would underutilize the pipe.
-+	 */
-+	case BBR_BW_PROBE_DOWN:
-+		if (bbr_check_time_to_probe_bw(sk, rs))
-+			return;		/* already decided state transition */
-+		if (bbr_check_time_to_cruise(sk, inflight, bw))
-+			bbr_start_bw_probe_cruise(sk);
-+		break;
-+
-+	default:
-+		WARN_ONCE(1, "BBR invalid cycle index %u\n", bbr->cycle_idx);
-+	}
-+}
-+
-+/* Exiting PROBE_RTT, so return to bandwidth probing in STARTUP or PROBE_BW. */
-+static void bbr_exit_probe_rtt(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_lower_bounds(sk);
-+	if (bbr_full_bw_reached(sk)) {
-+		bbr->mode = BBR_PROBE_BW;
-+		/* Raising inflight after PROBE_RTT may cause loss, so reset
-+		 * the PROBE_BW clock and schedule the next bandwidth probe for
-+		 * a friendly and randomized future point in time.
-+		 */
-+		bbr_start_bw_probe_down(sk);
-+		/* Since we are exiting PROBE_RTT, we know inflight is
-+		 * below our estimated BDP, so it is reasonable to cruise.
-+		 */
-+		bbr_start_bw_probe_cruise(sk);
-+	} else {
-+		bbr->mode = BBR_STARTUP;
-+	}
-+}
-+
-+/* Exit STARTUP based on loss rate > 1% and loss gaps in round >= N. Wait until
-+ * the end of the round in recovery to get a good estimate of how many packets
-+ * have been lost, and how many we need to drain with a low pacing rate.
-+ */
-+static void bbr_check_loss_too_high_in_startup(struct sock *sk,
-+						const struct rate_sample *rs)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr_full_bw_reached(sk))
-+		return;
-+
-+	/* For STARTUP exit, check the loss rate at the end of each round trip
-+	 * of Recovery episodes in STARTUP. We check the loss rate at the end
-+	 * of the round trip to filter out noisy/low loss and have a better
-+	 * sense of inflight (extent of loss), so we can drain more accurately.
-+	 */
-+	if (rs->losses && bbr->loss_events_in_round < 0xf)
-+		bbr->loss_events_in_round++;  /* update saturating counter */
-+	if (bbr_param(sk, full_loss_cnt) && bbr->loss_round_start &&
-+	    inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery &&
-+	    bbr->loss_events_in_round >= bbr_param(sk, full_loss_cnt) &&
-+	    bbr_is_inflight_too_high(sk, rs)) {
-+		bbr_handle_queue_too_high_in_startup(sk);
-+		return;
-+	}
-+	if (bbr->loss_round_start)
-+		bbr->loss_events_in_round = 0;
-+}
-+
-+/* Estimate when the pipe is full, using the change in delivery rate: BBR
-+ * estimates bw probing filled the pipe if the estimated bw hasn't changed by
-+ * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited
-+ * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the
-+ * higher rwin, 3: we get higher delivery rate samples. Or transient
-+ * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar
-+ * design goal, but uses delay and inter-ACK spacing instead of bandwidth.
-+ */
-+static void bbr_check_full_bw_reached(struct sock *sk,
-+				       const struct rate_sample *rs,
-+				       struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 bw_thresh, full_cnt, thresh;
-+
-+	if (bbr->full_bw_now || rs->is_app_limited)
-+		return;
-+
-+	thresh = bbr_param(sk, full_bw_thresh);
-+	full_cnt = bbr_param(sk, full_bw_cnt);
-+	bw_thresh = (u64)bbr->full_bw * thresh >> BBR_SCALE;
-+	if (ctx->sample_bw >= bw_thresh) {
-+		bbr_reset_full_bw(sk);
-+		bbr->full_bw = ctx->sample_bw;
-+		return;
-+	}
-+	if (!bbr->round_start)
-+		return;
-+	++bbr->full_bw_cnt;
-+	bbr->full_bw_now = bbr->full_bw_cnt >= full_cnt;
-+	bbr->full_bw_reached |= bbr->full_bw_now;
-+}
-+
-+/* If pipe is probably full, drain the queue and then enter steady-state. */
-+static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs,
-+			    struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) {
-+		bbr->mode = BBR_DRAIN;	/* drain queue we created */
-+		/* Set ssthresh to export purely for monitoring, to signal
-+		 * completion of initial STARTUP by setting to a non-
-+		 * TCP_INFINITE_SSTHRESH value (ssthresh is not used by BBR).
-+		 */
-+		tcp_sk(sk)->snd_ssthresh =
-+				bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+		bbr_reset_congestion_signals(sk);
-+	}	/* fall through to check if in-flight is already small: */
-+	if (bbr->mode == BBR_DRAIN &&
-+	    bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <=
-+	    bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) {
-+		bbr->mode = BBR_PROBE_BW;
-+		bbr_start_bw_probe_down(sk);
-+	}
-+}
-+
-+static void bbr_update_model(struct sock *sk, const struct rate_sample *rs,
-+			      struct bbr_context *ctx)
-+{
-+	bbr_update_congestion_signals(sk, rs, ctx);
-+	bbr_update_ack_aggregation(sk, rs);
-+	bbr_check_loss_too_high_in_startup(sk, rs);
-+	bbr_check_full_bw_reached(sk, rs, ctx);
-+	bbr_check_drain(sk, rs, ctx);
-+	bbr_update_cycle_phase(sk, rs, ctx);
-+	bbr_update_min_rtt(sk, rs);
-+}
-+
-+/* Fast path for app-limited case.
-+ *
-+ * On each ack, we execute bbr state machine, which primarily consists of:
-+ * 1) update model based on new rate sample, and
-+ * 2) update control based on updated model or state change.
-+ *
-+ * There are certain workload/scenarios, e.g. app-limited case, where
-+ * either we can skip updating model or we can skip update of both model
-+ * as well as control. This provides signifcant softirq cpu savings for
-+ * processing incoming acks.
-+ *
-+ * In case of app-limited, if there is no congestion (loss/ecn) and
-+ * if observed bw sample is less than current estimated bw, then we can
-+ * skip some of the computation in bbr state processing:
-+ *
-+ * - if there is no rtt/mode/phase change: In this case, since all the
-+ *   parameters of the network model are constant, we can skip model
-+ *   as well control update.
-+ *
-+ * - else we can skip rest of the model update. But we still need to
-+ *   update the control to account for the new rtt/mode/phase.
-+ *
-+ * Returns whether we can take fast path or not.
-+ */
-+static bool bbr_run_fast_path(struct sock *sk, bool *update_model,
-+		const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	u32 prev_min_rtt_us, prev_mode;
-+
-+	if (bbr_param(sk, fast_path) && bbr->try_fast_path &&
-+	    rs->is_app_limited && ctx->sample_bw < bbr_max_bw(sk) &&
-+	    !bbr->loss_in_round && !bbr->ecn_in_round ) {
-+		prev_mode = bbr->mode;
-+		prev_min_rtt_us = bbr->min_rtt_us;
-+		bbr_check_drain(sk, rs, ctx);
-+		bbr_update_cycle_phase(sk, rs, ctx);
-+		bbr_update_min_rtt(sk, rs);
-+
-+		if (bbr->mode == prev_mode &&
-+		    bbr->min_rtt_us == prev_min_rtt_us &&
-+		    bbr->try_fast_path) {
-+			return true;
-+		}
-+
-+		/* Skip model update, but control still needs to be updated */
-+		*update_model = false;
-+	}
-+	return false;
-+}
-+
-+__bpf_kfunc static void bbr_main(struct sock *sk, u32 ack, int flag,
-+				 const struct rate_sample *rs)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct bbr_context ctx = { 0 };
-+	bool update_model = true;
-+	u32 bw, round_delivered;
-+	int ce_ratio = -1;
-+
-+	round_delivered = bbr_update_round_start(sk, rs, &ctx);
-+	if (bbr->round_start) {
-+		bbr->rounds_since_probe =
-+			min_t(s32, bbr->rounds_since_probe + 1, 0xFF);
-+		ce_ratio = bbr_update_ecn_alpha(sk);
-+	}
-+	bbr_plb(sk, rs, ce_ratio);
-+
-+	bbr->ecn_in_round  |= (bbr->ecn_eligible && rs->is_ece);
-+	bbr_calculate_bw_sample(sk, rs, &ctx);
-+	bbr_update_latest_delivery_signals(sk, rs, &ctx);
-+
-+	if (bbr_run_fast_path(sk, &update_model, rs, &ctx))
-+		goto out;
-+
-+	if (update_model)
-+		bbr_update_model(sk, rs, &ctx);
-+
-+	bbr_update_gains(sk);
-+	bw = bbr_bw(sk);
-+	bbr_set_pacing_rate(sk, bw, bbr->pacing_gain);
-+	bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain,
-+		     tcp_snd_cwnd(tp), &ctx);
-+	bbr_bound_cwnd_for_inflight_model(sk);
-+
-+out:
-+	bbr_advance_latest_delivery_signals(sk, rs, &ctx);
-+	bbr->prev_ca_state = inet_csk(sk)->icsk_ca_state;
-+	bbr->loss_in_cycle |= rs->lost > 0;
-+	bbr->ecn_in_cycle  |= rs->delivered_ce > 0;
-+}
-+
-+__bpf_kfunc static void bbr_init(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr->initialized = 1;
-+
-+	bbr->init_cwnd = min(0x7FU, tcp_snd_cwnd(tp));
-+	bbr->prior_cwnd = tp->prior_cwnd;
-+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
-+	bbr->next_rtt_delivered = tp->delivered;
-+	bbr->prev_ca_state = TCP_CA_Open;
-+
-+	bbr->probe_rtt_done_stamp = 0;
-+	bbr->probe_rtt_round_done = 0;
-+	bbr->probe_rtt_min_us = tcp_min_rtt(tp);
-+	bbr->probe_rtt_min_stamp = tcp_jiffies32;
-+	bbr->min_rtt_us = tcp_min_rtt(tp);
-+	bbr->min_rtt_stamp = tcp_jiffies32;
-+
-+	bbr->has_seen_rtt = 0;
-+	bbr_init_pacing_rate_from_rtt(sk);
-+
-+	bbr->round_start = 0;
-+	bbr->idle_restart = 0;
-+	bbr->full_bw_reached = 0;
-+	bbr->full_bw = 0;
-+	bbr->full_bw_cnt = 0;
-+	bbr->cycle_mstamp = 0;
-+	bbr->cycle_idx = 0;
-+
-+	bbr_reset_startup_mode(sk);
-+
-+	bbr->ack_epoch_mstamp = tp->tcp_mstamp;
-+	bbr->ack_epoch_acked = 0;
-+	bbr->extra_acked_win_rtts = 0;
-+	bbr->extra_acked_win_idx = 0;
-+	bbr->extra_acked[0] = 0;
-+	bbr->extra_acked[1] = 0;
-+
-+	bbr->ce_state = 0;
-+	bbr->prior_rcv_nxt = tp->rcv_nxt;
-+	bbr->try_fast_path = 0;
-+
-+	cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED);
-+
-+	/* Start sampling ECN mark rate after first full flight is ACKed: */
-+	bbr->loss_round_delivered = tp->delivered + 1;
-+	bbr->loss_round_start = 0;
-+	bbr->undo_bw_lo = 0;
-+	bbr->undo_inflight_lo = 0;
-+	bbr->undo_inflight_hi = 0;
-+	bbr->loss_events_in_round = 0;
-+	bbr->startup_ecn_rounds = 0;
-+	bbr_reset_congestion_signals(sk);
-+	bbr->bw_lo = ~0U;
-+	bbr->bw_hi[0] = 0;
-+	bbr->bw_hi[1] = 0;
-+	bbr->inflight_lo = ~0U;
-+	bbr->inflight_hi = ~0U;
-+	bbr_reset_full_bw(sk);
-+	bbr->bw_probe_up_cnt = ~0U;
-+	bbr->bw_probe_up_acks = 0;
-+	bbr->bw_probe_up_rounds = 0;
-+	bbr->probe_wait_us = 0;
-+	bbr->stopped_risky_probe = 0;
-+	bbr->ack_phase = BBR_ACKS_INIT;
-+	bbr->rounds_since_probe = 0;
-+	bbr->bw_probe_samples = 0;
-+	bbr->prev_probe_too_high = 0;
-+	bbr->ecn_eligible = 0;
-+	bbr->ecn_alpha = bbr_param(sk, ecn_alpha_init);
-+	bbr->alpha_last_delivered = 0;
-+	bbr->alpha_last_delivered_ce = 0;
-+	bbr->plb.pause_until = 0;
-+
-+	tp->fast_ack_mode = bbr_fast_ack_mode ? 1 : 0;
-+
-+	if (bbr_can_use_ecn(sk))
-+		tp->ecn_flags |= TCP_ECN_ECT_PERMANENT;
-+}
-+
-+/* BBR marks the current round trip as a loss round. */
-+static void bbr_note_loss(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	/* Capture "current" data over the full round trip of loss, to
-+	 * have a better chance of observing the full capacity of the path.
-+	 */
-+	if (!bbr->loss_in_round)  /* first loss in this round trip? */
-+		bbr->loss_round_delivered = tp->delivered;  /* set round trip */
-+	bbr->loss_in_round = 1;
-+	bbr->loss_in_cycle = 1;
-+}
-+
-+/* Core TCP stack informs us that the given skb was just marked lost. */
-+__bpf_kfunc static void bbr_skb_marked_lost(struct sock *sk,
-+					    const struct sk_buff *skb)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
-+	struct rate_sample rs = {};
-+
-+	bbr_note_loss(sk);
-+
-+	if (!bbr->bw_probe_samples)
-+		return;  /* not an skb sent while probing for bandwidth */
-+	if (unlikely(!scb->tx.delivered_mstamp))
-+		return;  /* skb was SACKed, reneged, marked lost; ignore it */
-+	/* We are probing for bandwidth. Construct a rate sample that
-+	 * estimates what happened in the flight leading up to this lost skb,
-+	 * then see if the loss rate went too high, and if so at which packet.
-+	 */
-+	rs.tx_in_flight = scb->tx.in_flight;
-+	rs.lost = tp->lost - scb->tx.lost;
-+	rs.is_app_limited = scb->tx.is_app_limited;
-+	if (bbr_is_inflight_too_high(sk, &rs)) {
-+		rs.tx_in_flight = bbr_inflight_hi_from_lost_skb(sk, &rs, skb);
-+		bbr_handle_inflight_too_high(sk, &rs);
-+	}
-+}
-+
-+static void bbr_run_loss_probe_recovery(struct sock *sk)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+	struct rate_sample rs = {0};
-+
-+	bbr_note_loss(sk);
-+
-+	if (!bbr->bw_probe_samples)
-+		return;  /* not sent while probing for bandwidth */
-+	/* We are probing for bandwidth. Construct a rate sample that
-+	 * estimates what happened in the flight leading up to this
-+	 * loss, then see if the loss rate went too high.
-+	 */
-+	rs.lost = 1;	/* TLP probe repaired loss of a single segment */
-+	rs.tx_in_flight = bbr->inflight_latest + rs.lost;
-+	rs.is_app_limited = tp->tlp_orig_data_app_limited;
-+	if (bbr_is_inflight_too_high(sk, &rs))
-+		bbr_handle_inflight_too_high(sk, &rs);
-+}
-+
-+/* Revert short-term model if current loss recovery event was spurious. */
-+__bpf_kfunc static u32 bbr_undo_cwnd(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_reset_full_bw(sk); /* spurious slow-down; reset full bw detector */
-+	bbr->loss_in_round = 0;
-+
-+	/* Revert to cwnd and other state saved before loss episode. */
-+	bbr->bw_lo = max(bbr->bw_lo, bbr->undo_bw_lo);
-+	bbr->inflight_lo = max(bbr->inflight_lo, bbr->undo_inflight_lo);
-+	bbr->inflight_hi = max(bbr->inflight_hi, bbr->undo_inflight_hi);
-+	bbr->try_fast_path = 0;  /* take slow path to set proper cwnd, pacing */
-+	return bbr->prior_cwnd;
-+}
-+
-+/* Entering loss recovery, so save state for when we undo recovery. */
-+__bpf_kfunc static u32 bbr_ssthresh(struct sock *sk)
-+{
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	bbr_save_cwnd(sk);
-+	/* For undo, save state that adapts based on loss signal. */
-+	bbr->undo_bw_lo		= bbr->bw_lo;
-+	bbr->undo_inflight_lo	= bbr->inflight_lo;
-+	bbr->undo_inflight_hi	= bbr->inflight_hi;
-+	return tcp_sk(sk)->snd_ssthresh;
-+}
-+
-+static enum tcp_bbr_phase bbr_get_phase(struct bbr *bbr)
-+{
-+	switch (bbr->mode) {
-+	case BBR_STARTUP:
-+		return BBR_PHASE_STARTUP;
-+	case BBR_DRAIN:
-+		return BBR_PHASE_DRAIN;
-+	case BBR_PROBE_BW:
-+		break;
-+	case BBR_PROBE_RTT:
-+		return BBR_PHASE_PROBE_RTT;
-+	default:
-+		return BBR_PHASE_INVALID;
-+	}
-+	switch (bbr->cycle_idx) {
-+	case BBR_BW_PROBE_UP:
-+		return BBR_PHASE_PROBE_BW_UP;
-+	case BBR_BW_PROBE_DOWN:
-+		return BBR_PHASE_PROBE_BW_DOWN;
-+	case BBR_BW_PROBE_CRUISE:
-+		return BBR_PHASE_PROBE_BW_CRUISE;
-+	case BBR_BW_PROBE_REFILL:
-+		return BBR_PHASE_PROBE_BW_REFILL;
-+	default:
-+		return BBR_PHASE_INVALID;
-+	}
-+}
-+
-+static size_t bbr_get_info(struct sock *sk, u32 ext, int *attr,
-+			    union tcp_cc_info *info)
-+{
-+	if (ext & (1 << (INET_DIAG_BBRINFO - 1)) ||
-+	    ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
-+		struct bbr *bbr = inet_csk_ca(sk);
-+		u64 bw = bbr_bw_bytes_per_sec(sk, bbr_bw(sk));
-+		u64 bw_hi = bbr_bw_bytes_per_sec(sk, bbr_max_bw(sk));
-+		u64 bw_lo = bbr->bw_lo == ~0U ?
-+			~0ULL : bbr_bw_bytes_per_sec(sk, bbr->bw_lo);
-+		struct tcp_bbr_info *bbr_info = &info->bbr;
-+
-+		memset(bbr_info, 0, sizeof(*bbr_info));
-+		bbr_info->bbr_bw_lo		= (u32)bw;
-+		bbr_info->bbr_bw_hi		= (u32)(bw >> 32);
-+		bbr_info->bbr_min_rtt		= bbr->min_rtt_us;
-+		bbr_info->bbr_pacing_gain	= bbr->pacing_gain;
-+		bbr_info->bbr_cwnd_gain		= bbr->cwnd_gain;
-+		bbr_info->bbr_bw_hi_lsb		= (u32)bw_hi;
-+		bbr_info->bbr_bw_hi_msb		= (u32)(bw_hi >> 32);
-+		bbr_info->bbr_bw_lo_lsb		= (u32)bw_lo;
-+		bbr_info->bbr_bw_lo_msb		= (u32)(bw_lo >> 32);
-+		bbr_info->bbr_mode		= bbr->mode;
-+		bbr_info->bbr_phase		= (__u8)bbr_get_phase(bbr);
-+		bbr_info->bbr_version		= (__u8)BBR_VERSION;
-+		bbr_info->bbr_inflight_lo	= bbr->inflight_lo;
-+		bbr_info->bbr_inflight_hi	= bbr->inflight_hi;
-+		bbr_info->bbr_extra_acked	= bbr_extra_acked(sk);
-+		*attr = INET_DIAG_BBRINFO;
-+		return sizeof(*bbr_info);
-+	}
-+	return 0;
-+}
-+
-+__bpf_kfunc static void bbr_set_state(struct sock *sk, u8 new_state)
-+{
-+	struct tcp_sock *tp = tcp_sk(sk);
-+	struct bbr *bbr = inet_csk_ca(sk);
-+
-+	if (new_state == TCP_CA_Loss) {
-+
-+		bbr->prev_ca_state = TCP_CA_Loss;
-+		tcp_plb_update_state_upon_rto(sk, &bbr->plb);
-+		/* The tcp_write_timeout() call to sk_rethink_txhash() likely
-+		 * repathed this flow, so re-learn the min network RTT on the
-+		 * new path:
-+		 */
-+		bbr_reset_full_bw(sk);
-+		if (!bbr_is_probing_bandwidth(sk) && bbr->inflight_lo == ~0U) {
-+			/* bbr_adapt_lower_bounds() needs cwnd before
-+			 * we suffered an RTO, to update inflight_lo:
-+			 */
-+			bbr->inflight_lo =
-+				max(tcp_snd_cwnd(tp), bbr->prior_cwnd);
-+		}
-+	} else if (bbr->prev_ca_state == TCP_CA_Loss &&
-+		   new_state != TCP_CA_Loss) {
-+		bbr_exit_loss_recovery(sk);
-+	}
-+}
-+
-+
-+static struct tcp_congestion_ops tcp_bbrv3_cong_ops __read_mostly = {
-+	.flags		= TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS,
-+	.name		= "bbrv3",
-+	.owner		= THIS_MODULE,
-+	.init		= bbr_init,
-+	.cong_control	= bbr_main,
-+	.sndbuf_expand	= bbr_sndbuf_expand,
-+	.skb_marked_lost = bbr_skb_marked_lost,
-+	.undo_cwnd	= bbr_undo_cwnd,
-+	.cwnd_event	= bbr_cwnd_event,
-+	.ssthresh	= bbr_ssthresh,
-+	.tso_segs	= bbr_tso_segs,
-+	.get_info	= bbr_get_info,
-+	.set_state	= bbr_set_state,
-+};
-+
-+BTF_KFUNCS_START(tcp_bbrv3_check_kfunc_ids)
-+BTF_ID_FLAGS(func, bbr_init)
-+BTF_ID_FLAGS(func, bbr_main)
-+BTF_ID_FLAGS(func, bbr_sndbuf_expand)
-+BTF_ID_FLAGS(func, bbr_skb_marked_lost)
-+BTF_ID_FLAGS(func, bbr_undo_cwnd)
-+BTF_ID_FLAGS(func, bbr_cwnd_event)
-+BTF_ID_FLAGS(func, bbr_ssthresh)
-+BTF_ID_FLAGS(func, bbr_tso_segs)
-+BTF_ID_FLAGS(func, bbr_set_state)
-+BTF_KFUNCS_END(tcp_bbrv3_check_kfunc_ids)
-+
-+static const struct btf_kfunc_id_set tcp_bbrv3_kfunc_set = {
-+	.owner = THIS_MODULE,
-+	.set   = &tcp_bbrv3_check_kfunc_ids,
-+};
-+
-+static int __init bbrv3_register(void)
-+{
-+	int ret;
-+
-+	BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE);
-+
-+	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &tcp_bbrv3_kfunc_set);
-+	if (ret < 0)
-+		return ret;
-+	return tcp_register_congestion_control(&tcp_bbrv3_cong_ops);
-+}
-+
-+static void __exit bbrv3_unregister(void)
-+{
-+	tcp_unregister_congestion_control(&tcp_bbrv3_cong_ops);
-+}
-+
-+module_init(bbrv3_register);
-+module_exit(bbrv3_unregister);
-+
-+MODULE_AUTHOR("Van Jacobson <vanj@google.com>");
-+MODULE_AUTHOR("Neal Cardwell <ncardwell@google.com>");
-+MODULE_AUTHOR("Yuchung Cheng <ycheng@google.com>");
-+MODULE_AUTHOR("Soheil Hassas Yeganeh <soheil@google.com>");
-+MODULE_AUTHOR("Priyaranjan Jha <priyarjha@google.com>");
-+MODULE_AUTHOR("Yousuk Seung <ysseung@google.com>");
-+MODULE_AUTHOR("Kevin Yang <yyd@google.com>");
-+MODULE_AUTHOR("Arjun Roy <arjunroy@google.com>");
-+MODULE_AUTHOR("David Morley <morleyd@google.com>");
-+
-+MODULE_LICENSE("Dual BSD/GPL");
-+MODULE_DESCRIPTION("TCP BBRv3 (Bottleneck Bandwidth and RTT Version 3)");
-+MODULE_VERSION(__stringify(BBR_VERSION));