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-rw-r--r--SOURCES/tkg-BBRv2.patch3311
1 files changed, 0 insertions, 3311 deletions
diff --git a/SOURCES/tkg-BBRv2.patch b/SOURCES/tkg-BBRv2.patch
deleted file mode 100644
index 35640e3..0000000
--- a/SOURCES/tkg-BBRv2.patch
+++ /dev/null
@@ -1,3311 +0,0 @@
-From eff7e1edf2fec63bac1a81f8c86295dd3f48422a Mon Sep 17 00:00:00 2001
-From: Oleksandr Natalenko <oleksandr@natalenko.name>
-Date: Mon, 4 Apr 2022 08:23:19 +0200
-Subject: [PATCH] tcp_bbr2: introduce BBRv2
-
-Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
----
- include/linux/tcp.h | 3 +-
- include/net/inet_connection_sock.h | 3 +-
- include/net/tcp.h | 41 +-
- include/uapi/linux/inet_diag.h | 33 +
- net/ipv4/Kconfig | 22 +
- net/ipv4/Makefile | 1 +
- net/ipv4/tcp.c | 1 +
- net/ipv4/tcp_bbr.c | 38 +-
- net/ipv4/tcp_bbr2.c | 2674 ++++++++++++++++++++++++++++
- net/ipv4/tcp_cong.c | 1 +
- net/ipv4/tcp_input.c | 27 +-
- net/ipv4/tcp_output.c | 26 +-
- net/ipv4/tcp_rate.c | 30 +-
- net/ipv4/tcp_timer.c | 1 +
- 14 files changed, 2867 insertions(+), 34 deletions(-)
- create mode 100644 net/ipv4/tcp_bbr2.c
-
-diff --git a/include/linux/tcp.h b/include/linux/tcp.h
-index 41b1da621a45..d8f94ef1a297 100644
---- a/include/linux/tcp.h
-+++ b/include/linux/tcp.h
-@@ -255,7 +255,8 @@ struct tcp_sock {
- u8 compressed_ack;
- u8 dup_ack_counter:2,
- tlp_retrans:1, /* TLP is a retransmission */
-- unused:5;
-+ fast_ack_mode:2, /* which fast ack mode ? */
-+ unused:3;
- u32 chrono_start; /* Start time in jiffies of a TCP chrono */
- u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */
- u8 chrono_type:2, /* current chronograph type */
-diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
-index c2b15f7e5516..d85858efa571 100644
---- a/include/net/inet_connection_sock.h
-+++ b/include/net/inet_connection_sock.h
-@@ -135,7 +135,8 @@ struct inet_connection_sock {
- u32 icsk_probes_tstamp;
- u32 icsk_user_timeout;
-
-- u64 icsk_ca_priv[104 / sizeof(u64)];
-+/* XXX inflated by temporary internal debugging info */
-+ u64 icsk_ca_priv[216 / sizeof(u64)];
- #define ICSK_CA_PRIV_SIZE sizeof_field(struct inet_connection_sock, icsk_ca_priv)
- };
-
-diff --git a/include/net/tcp.h b/include/net/tcp.h
-index 14d45661a84d..7261fae79403 100644
---- a/include/net/tcp.h
-+++ b/include/net/tcp.h
-@@ -375,6 +375,7 @@ 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_ECT_PERMANENT 16
-
- enum tcp_tw_status {
- TCP_TW_SUCCESS = 0,
-@@ -823,6 +824,11 @@ static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
- return max_t(s64, t1 - t0, 0);
- }
-
-+static inline u32 tcp_stamp32_us_delta(u32 t1, u32 t0)
-+{
-+ return max_t(s32, t1 - t0, 0);
-+}
-+
- static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)
- {
- return tcp_ns_to_ts(skb->skb_mstamp_ns);
-@@ -898,9 +904,14 @@ struct tcp_skb_cb {
- /* pkts S/ACKed so far upon tx of skb, incl retrans: */
- __u32 delivered;
- /* start of send pipeline phase */
-- u64 first_tx_mstamp;
-+ u32 first_tx_mstamp;
- /* when we reached the "delivered" count */
-- u64 delivered_mstamp;
-+ u32 delivered_mstamp;
-+#define TCPCB_IN_FLIGHT_BITS 20
-+#define TCPCB_IN_FLIGHT_MAX ((1U << TCPCB_IN_FLIGHT_BITS) - 1)
-+ u32 in_flight:20, /* packets in flight at transmit */
-+ unused2:12;
-+ u32 lost; /* packets lost so far upon tx of skb */
- } tx; /* only used for outgoing skbs */
- union {
- struct inet_skb_parm h4;
-@@ -1026,7 +1037,11 @@ enum tcp_ca_ack_event_flags {
- #define TCP_CONG_NON_RESTRICTED 0x1
- /* Requires ECN/ECT set on all packets */
- #define TCP_CONG_NEEDS_ECN 0x2
--#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
-+/* Wants notification of CE events (CA_EVENT_ECN_IS_CE, CA_EVENT_ECN_NO_CE). */
-+#define TCP_CONG_WANTS_CE_EVENTS 0x4
-+#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | \
-+ TCP_CONG_NEEDS_ECN | \
-+ TCP_CONG_WANTS_CE_EVENTS)
-
- union tcp_cc_info;
-
-@@ -1046,8 +1061,11 @@ struct ack_sample {
- */
- struct rate_sample {
- u64 prior_mstamp; /* starting timestamp for interval */
-+ u32 prior_lost; /* tp->lost at "prior_mstamp" */
- u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
- u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */
-+ u32 tx_in_flight; /* packets in flight at starting timestamp */
-+ s32 lost; /* number of packets lost over interval */
- s32 delivered; /* number of packets delivered over interval */
- s32 delivered_ce; /* number of packets delivered w/ CE marks*/
- long interval_us; /* time for tp->delivered to incr "delivered" */
-@@ -1061,6 +1079,7 @@ struct rate_sample {
- bool is_app_limited; /* is sample from packet with bubble in pipe? */
- bool is_retrans; /* is sample from retransmission? */
- bool is_ack_delayed; /* is this (likely) a delayed ACK? */
-+ bool is_ece; /* did this ACK have ECN marked? */
- };
-
- struct tcp_congestion_ops {
-@@ -1084,8 +1103,11 @@ struct tcp_congestion_ops {
- /* hook for packet ack accounting (optional) */
- void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
-
-- /* override sysctl_tcp_min_tso_segs */
-- u32 (*min_tso_segs)(struct sock *sk);
-+ /* pick target number of segments per TSO/GSO skb (optional): */
-+ u32 (*tso_segs)(struct sock *sk, unsigned int mss_now);
-+
-+ /* react to a specific lost skb (optional) */
-+ void (*skb_marked_lost)(struct sock *sk, const struct sk_buff *skb);
-
- /* call when packets are delivered to update cwnd and pacing rate,
- * after all the ca_state processing. (optional)
-@@ -1148,6 +1170,14 @@ static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
- }
- #endif
-
-+static inline bool tcp_ca_wants_ce_events(const struct sock *sk)
-+{
-+ const struct inet_connection_sock *icsk = inet_csk(sk);
-+
-+ return icsk->icsk_ca_ops->flags & (TCP_CONG_NEEDS_ECN |
-+ TCP_CONG_WANTS_CE_EVENTS);
-+}
-+
- static inline bool tcp_ca_needs_ecn(const struct sock *sk)
- {
- const struct inet_connection_sock *icsk = inet_csk(sk);
-@@ -1167,6 +1197,7 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
- void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
-
- /* From tcp_rate.c */
-+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb);
- void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
- void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
- struct rate_sample *rs);
-diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
-index 50655de04c9b..0e24f11627d5 100644
---- a/include/uapi/linux/inet_diag.h
-+++ b/include/uapi/linux/inet_diag.h
-@@ -231,9 +231,42 @@ struct tcp_bbr_info {
- __u32 bbr_cwnd_gain; /* cwnd gain shifted left 8 bits */
- };
-
-+/* Phase as reported in netlink/ss stats. */
-+enum tcp_bbr2_phase {
-+ BBR2_PHASE_INVALID = 0,
-+ BBR2_PHASE_STARTUP = 1,
-+ BBR2_PHASE_DRAIN = 2,
-+ BBR2_PHASE_PROBE_RTT = 3,
-+ BBR2_PHASE_PROBE_BW_UP = 4,
-+ BBR2_PHASE_PROBE_BW_DOWN = 5,
-+ BBR2_PHASE_PROBE_BW_CRUISE = 6,
-+ BBR2_PHASE_PROBE_BW_REFILL = 7
-+};
-+
-+struct tcp_bbr2_info {
-+ /* u64 bw: bandwidth (app throughput) estimate in Byte per sec: */
-+ __u32 bbr_bw_lsb; /* lower 32 bits of bw */
-+ __u32 bbr_bw_msb; /* 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 */
-+ __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; /* MUST be at this offset in struct */
-+ __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 */
-+};
-+
- union tcp_cc_info {
- struct tcpvegas_info vegas;
- struct tcp_dctcp_info dctcp;
- struct tcp_bbr_info bbr;
-+ struct tcp_bbr2_info bbr2;
- };
- #endif /* _UAPI_INET_DIAG_H_ */
-diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
-index 2dfb12230f08..b6bec331a82e 100644
---- a/net/ipv4/Kconfig
-+++ b/net/ipv4/Kconfig
-@@ -678,6 +678,24 @@ 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_BBR2
-+ tristate "BBR2 TCP"
-+ default n
-+ help
-+
-+ BBR2 TCP congestion control is a model-based congestion control
-+ algorithm that aims to maximize network utilization, keep queues and
-+ retransmit rates low, and to be able to coexist with Reno/CUBIC in
-+ common scenarios. It builds an explicit model of the network path. It
-+ tolerates a targeted degree of random packet loss and delay that are
-+ unrelated to congestion. It can operate over LAN, WAN, cellular, wifi,
-+ or cable modem links, and can use DCTCP-L4S-style ECN signals. It can
-+ coexist with flows that use loss-based congestion control, and can
-+ operate with shallow buffers, deep buffers, bufferbloat, policers, or
-+ AQM schemes that do not provide a delay signal. It requires pacing,
-+ using either TCP internal pacing or the fq ("Fair Queue") pacing packet
-+ scheduler.
-+
- choice
- prompt "Default TCP congestion control"
- default DEFAULT_CUBIC
-@@ -715,6 +733,9 @@ choice
- config DEFAULT_BBR
- bool "BBR" if TCP_CONG_BBR=y
-
-+ config DEFAULT_BBR2
-+ bool "BBR2" if TCP_CONG_BBR2=y
-+
- config DEFAULT_RENO
- bool "Reno"
- endchoice
-@@ -739,6 +760,7 @@ config DEFAULT_TCP_CONG
- default "dctcp" if DEFAULT_DCTCP
- default "cdg" if DEFAULT_CDG
- default "bbr" if DEFAULT_BBR
-+ default "bbr2" if DEFAULT_BBR2
- default "cubic"
-
- config TCP_MD5SIG
-diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
-index bbdd9c44f14e..8dee1547d820 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-$(CONFIG_TCP_CONG_BBR2) += tcp_bbr2.o
- obj-$(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.c b/net/ipv4/tcp.c
-index 4f2205756cfe..c139747666dd 100644
---- a/net/ipv4/tcp.c
-+++ b/net/ipv4/tcp.c
-@@ -3188,6 +3188,7 @@ int tcp_disconnect(struct sock *sk, int flags)
- tp->rx_opt.dsack = 0;
- tp->rx_opt.num_sacks = 0;
- tp->rcv_ooopack = 0;
-+ tp->fast_ack_mode = 0;
-
-
- /* Clean up fastopen related fields */
-diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
-index 54eec33c6e1c..bfbf158c71f4 100644
---- a/net/ipv4/tcp_bbr.c
-+++ b/net/ipv4/tcp_bbr.c
-@@ -294,26 +294,40 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
- sk->sk_pacing_rate = rate;
- }
-
--/* override sysctl_tcp_min_tso_segs */
- __bpf_kfunc static u32 bbr_min_tso_segs(struct sock *sk)
- {
- return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2;
- }
-
-+/* Return the number of segments BBR would like in a TSO/GSO skb, given
-+ * a particular max gso size as a constraint.
-+ */
-+static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now,
-+ u32 gso_max_size)
-+{
-+ u32 segs;
-+ u64 bytes;
-+
-+ /* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */
-+ bytes = sk->sk_pacing_rate >> sk->sk_pacing_shift;
-+
-+ bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER);
-+ segs = max_t(u32, div_u64(bytes, mss_now), bbr_min_tso_segs(sk));
-+ return segs;
-+}
-+
-+/* 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 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);
-- 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 */
-@@ -1149,7 +1163,7 @@ static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = {
- .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,
- };
-diff --git a/net/ipv4/tcp_bbr2.c b/net/ipv4/tcp_bbr2.c
-new file mode 100644
-index 000000000000..488429f0f3d0
---- /dev/null
-+++ b/net/ipv4/tcp_bbr2.c
-@@ -0,0 +1,2674 @@
-+/* BBR (Bottleneck Bandwidth and RTT) congestion control, v2
-+ *
-+ * BBRv2 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 DCTCP/L4S-style 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/module.h>
-+#include <net/tcp.h>
-+#include <linux/inet_diag.h>
-+#include <linux/inet.h>
-+#include <linux/random.h>
-+
-+#include "tcp_dctcp.h"
-+
-+/* 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)
-+
-+#define FLAG_DEBUG_VERBOSE 0x1 /* Verbose debugging messages */
-+#define FLAG_DEBUG_LOOPBACK 0x2 /* Do NOT skip loopback addr */
-+
-+#define CYCLE_LEN 8 /* number of phases in a pacing gain cycle */
-+
-+/* 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 bbr_probe_rtt_win_ms window */
-+ u32 probe_rtt_min_stamp; /* timestamp of probe_rtt_min_us*/
-+ u32 next_rtt_delivered; /* scb->tx.delivered at end of round */
-+ u32 prior_rcv_nxt; /* tp->rcv_nxt when CE state last changed */
-+ u64 cycle_mstamp; /* time of this cycle phase start */
-+ u32 mode:3, /* 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? */
-+ unused2:11,
-+ idle_restart:1, /* restarting after idle? */
-+ probe_rtt_round_done:1, /* a BBR_PROBE_RTT round at 4 pkts? */
-+ cycle_idx:3, /* current index in pacing_gain cycle array */
-+ has_seen_rtt:1; /* have we seen an RTT sample yet? */
-+ u32 pacing_gain:11, /* current gain for setting pacing rate */
-+ cwnd_gain:11, /* 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 */
-+ init_cwnd:7; /* initial cwnd */
-+ 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 v2 state: */
-+ unused1:2,
-+ 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? */
-+ 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]; /* upper bound of sending bandwidth range*/
-+ 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 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 */
-+
-+ /* Params configurable using setsockopt. Refer to correspoding
-+ * module param for detailed description of params.
-+ */
-+ struct bbr_params {
-+ u32 high_gain:11, /* max allowed value: 2047 */
-+ drain_gain:10, /* max allowed value: 1023 */
-+ cwnd_gain:11; /* max allowed value: 2047 */
-+ u32 cwnd_min_target:4, /* max allowed value: 15 */
-+ min_rtt_win_sec:5, /* max allowed value: 31 */
-+ probe_rtt_mode_ms:9, /* max allowed value: 511 */
-+ full_bw_cnt:3, /* max allowed value: 7 */
-+ cwnd_tso_budget:1, /* allowed values: {0, 1} */
-+ unused3:6,
-+ drain_to_target:1, /* boolean */
-+ precise_ece_ack:1, /* boolean */
-+ extra_acked_in_startup:1, /* allowed values: {0, 1} */
-+ fast_path:1; /* boolean */
-+ u32 full_bw_thresh:10, /* max allowed value: 1023 */
-+ startup_cwnd_gain:11, /* max allowed value: 2047 */
-+ bw_probe_pif_gain:9, /* max allowed value: 511 */
-+ usage_based_cwnd:1, /* boolean */
-+ unused2:1;
-+ u16 probe_rtt_win_ms:14, /* max allowed value: 16383 */
-+ refill_add_inc:2; /* max allowed value: 3 */
-+ u16 extra_acked_gain:11, /* max allowed value: 2047 */
-+ extra_acked_win_rtts:5; /* max allowed value: 31*/
-+ u16 pacing_gain[CYCLE_LEN]; /* max allowed value: 1023 */
-+ /* Mostly BBR v2 parameters below here: */
-+ u32 ecn_alpha_gain:8, /* max allowed value: 255 */
-+ ecn_factor:8, /* max allowed value: 255 */
-+ ecn_thresh:8, /* max allowed value: 255 */
-+ beta:8; /* max allowed value: 255 */
-+ u32 ecn_max_rtt_us:19, /* max allowed value: 524287 */
-+ bw_probe_reno_gain:9, /* max allowed value: 511 */
-+ full_loss_cnt:4; /* max allowed value: 15 */
-+ u32 probe_rtt_cwnd_gain:8, /* max allowed value: 255 */
-+ inflight_headroom:8, /* max allowed value: 255 */
-+ loss_thresh:8, /* max allowed value: 255 */
-+ bw_probe_max_rounds:8; /* max allowed value: 255 */
-+ u32 bw_probe_rand_rounds:4, /* max allowed value: 15 */
-+ bw_probe_base_us:26, /* usecs: 0..2^26-1 (67 secs) */
-+ full_ecn_cnt:2; /* max allowed value: 3 */
-+ u32 bw_probe_rand_us:26, /* usecs: 0..2^26-1 (67 secs) */
-+ undo:1, /* boolean */
-+ tso_rtt_shift:4, /* max allowed value: 15 */
-+ unused5:1;
-+ u32 ecn_reprobe_gain:9, /* max allowed value: 511 */
-+ unused1:14,
-+ ecn_alpha_init:9; /* max allowed value: 256 */
-+ } params;
-+
-+ struct {
-+ u32 snd_isn; /* Initial sequence number */
-+ u32 rs_bw; /* last valid rate sample bw */
-+ u32 target_cwnd; /* target cwnd, based on BDP */
-+ u8 undo:1, /* Undo even happened but not yet logged */
-+ unused:7;
-+ char event; /* single-letter event debug codes */
-+ u16 unused2;
-+ } debug;
-+};
-+
-+struct bbr_context {
-+ u32 sample_bw;
-+ u32 target_cwnd;
-+ u32 log:1;
-+};
-+
-+/* Window length of min_rtt filter (in sec). Max allowed value is 31 (0x1F) */
-+static u32 bbr_min_rtt_win_sec = 10;
-+/* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode.
-+ * Max allowed value is 511 (0x1FF).
-+ */
-+static 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.
-+ * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC
-+ */
-+static u32 bbr_probe_rtt_win_ms = 5000;
-+/* Skip TSO below the following bandwidth (bits/sec): */
-+static int bbr_min_tso_rate = 1200000;
-+
-+/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting
-+ * in bigger TSO bursts. By default 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 u32 bbr_tso_rtt_shift = 9; /* halve allowance per 2^9 usecs, 512us */
-+
-+/* Select cwnd TSO budget approach:
-+ * 0: padding
-+ * 1: flooring
-+ */
-+static uint bbr_cwnd_tso_budget = 1;
-+
-+/* 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 high_gain value of 2/ln(2) because it's the smallest pacing gain
-+ * 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. Max allowed value is 2047 (0x7FF).
-+ */
-+static int bbr_high_gain = BBR_UNIT * 2885 / 1000 + 1;
-+/* The gain for deriving startup cwnd. Max allowed value is 2047 (0x7FF). */
-+static int bbr_startup_cwnd_gain = BBR_UNIT * 2885 / 1000 + 1;
-+/* The pacing gain of 1/high_gain in BBR_DRAIN is calculated to typically drain
-+ * the queue created in BBR_STARTUP in a single round. Max allowed value
-+ * is 1023 (0x3FF).
-+ */
-+static int bbr_drain_gain = BBR_UNIT * 1000 / 2885;
-+/* The gain for deriving steady-state cwnd tolerates delayed/stretched ACKs.
-+ * Max allowed value is 2047 (0x7FF).
-+ */
-+static int bbr_cwnd_gain = BBR_UNIT * 2;
-+/* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw.
-+ * Max allowed value for each element is 1023 (0x3FF).
-+ */
-+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, /* v2: refill the pipe again to 100% */
-+};
-+static 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... */
-+};
-+
-+/* 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. Max allowed value is 15 (0xF).
-+ */
-+static u32 bbr_cwnd_min_target = 4;
-+
-+/* Cwnd to BDP proportion in PROBE_RTT mode scaled by BBR_UNIT. Default: 50%.
-+ * Use 0 to disable. Max allowed value is 255.
-+ */
-+static u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2;
-+
-+/* To estimate if BBR_STARTUP mode (i.e. high_gain) has filled pipe... */
-+/* If bw has increased significantly (1.25x), there may be more bw available.
-+ * Max allowed value is 1023 (0x3FF).
-+ */
-+static u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4;
-+/* But after 3 rounds w/o significant bw growth, estimate pipe is full.
-+ * Max allowed value is 7 (0x7).
-+ */
-+static u32 bbr_full_bw_cnt = 3;
-+
-+static u32 bbr_flags; /* Debugging related stuff */
-+
-+/* Whether to debug using printk.
-+ */
-+static bool bbr_debug_with_printk;
-+
-+/* Whether to debug using ftrace event tcp:tcp_bbr_event.
-+ * Ignored when bbr_debug_with_printk is set.
-+ */
-+static bool bbr_debug_ftrace;
-+
-+/* Experiment: each cycle, try to hold sub-unity gain until inflight <= BDP. */
-+static bool bbr_drain_to_target = true; /* default: enabled */
-+
-+/* Experiment: Flags to control BBR with ECN behavior.
-+ */
-+static bool bbr_precise_ece_ack = true; /* default: enabled */
-+
-+/* The max rwin scaling shift factor is 14 (RFC 1323), so the max sane rwin is
-+ * (2^(16+14) B)/(1024 B/packet) = 1M packets.
-+ */
-+static u32 bbr_cwnd_warn_val = 1U << 20;
-+
-+static u16 bbr_debug_port_mask;
-+
-+/* BBR module parameters. These are module parameters only in Google prod.
-+ * Upstream these are intentionally not module parameters.
-+ */
-+static int bbr_pacing_gain_size = CYCLE_LEN;
-+
-+/* Gain factor for adding extra_acked to target cwnd: */
-+static int bbr_extra_acked_gain = 256;
-+
-+/* Window length of extra_acked window. Max allowed val is 31. */
-+static u32 bbr_extra_acked_win_rtts = 5;
-+
-+/* Max allowed val for ack_epoch_acked, after which sampling epoch is reset */
-+static u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20;
-+
-+/* Time period for clamping cwnd increment due to ack aggregation */
-+static u32 bbr_extra_acked_max_us = 100 * 1000;
-+
-+/* Use extra acked in startup ?
-+ * 0: disabled
-+ * 1: use latest extra_acked value from 1-2 rtt in startup
-+ */
-+static int bbr_extra_acked_in_startup = 1; /* default: enabled */
-+
-+/* Experiment: don't grow cwnd beyond twice of what we just probed. */
-+static bool bbr_usage_based_cwnd; /* default: disabled */
-+
-+/* For lab testing, researchers can enable BBRv2 ECN support with this flag,
-+ * when they know that any ECN marks that the connections experience will be
-+ * DCTCP/L4S-style ECN marks, rather than RFC3168 ECN marks.
-+ * TODO(ncardwell): Production use of the BBRv2 ECN functionality depends on
-+ * negotiation or configuration that is outside the scope of the BBRv2
-+ * alpha release.
-+ */
-+static bool bbr_ecn_enable = false;
-+
-+module_param_named(min_tso_rate, bbr_min_tso_rate, int, 0644);
-+module_param_named(tso_rtt_shift, bbr_tso_rtt_shift, int, 0644);
-+module_param_named(high_gain, bbr_high_gain, int, 0644);
-+module_param_named(drain_gain, bbr_drain_gain, int, 0644);
-+module_param_named(startup_cwnd_gain, bbr_startup_cwnd_gain, int, 0644);
-+module_param_named(cwnd_gain, bbr_cwnd_gain, int, 0644);
-+module_param_array_named(pacing_gain, bbr_pacing_gain, int,
-+ &bbr_pacing_gain_size, 0644);
-+module_param_named(cwnd_min_target, bbr_cwnd_min_target, uint, 0644);
-+module_param_named(probe_rtt_cwnd_gain,
-+ bbr_probe_rtt_cwnd_gain, uint, 0664);
-+module_param_named(cwnd_warn_val, bbr_cwnd_warn_val, uint, 0664);
-+module_param_named(debug_port_mask, bbr_debug_port_mask, ushort, 0644);
-+module_param_named(flags, bbr_flags, uint, 0644);
-+module_param_named(debug_ftrace, bbr_debug_ftrace, bool, 0644);
-+module_param_named(debug_with_printk, bbr_debug_with_printk, bool, 0644);
-+module_param_named(min_rtt_win_sec, bbr_min_rtt_win_sec, uint, 0644);
-+module_param_named(probe_rtt_mode_ms, bbr_probe_rtt_mode_ms, uint, 0644);
-+module_param_named(probe_rtt_win_ms, bbr_probe_rtt_win_ms, uint, 0644);
-+module_param_named(full_bw_thresh, bbr_full_bw_thresh, uint, 0644);
-+module_param_named(full_bw_cnt, bbr_full_bw_cnt, uint, 0644);
-+module_param_named(cwnd_tso_bduget, bbr_cwnd_tso_budget, uint, 0664);
-+module_param_named(extra_acked_gain, bbr_extra_acked_gain, int, 0664);
-+module_param_named(extra_acked_win_rtts,
-+ bbr_extra_acked_win_rtts, uint, 0664);
-+module_param_named(extra_acked_max_us,
-+ bbr_extra_acked_max_us, uint, 0664);
-+module_param_named(ack_epoch_acked_reset_thresh,
-+ bbr_ack_epoch_acked_reset_thresh, uint, 0664);
-+module_param_named(drain_to_target, bbr_drain_to_target, bool, 0664);
-+module_param_named(precise_ece_ack, bbr_precise_ece_ack, bool, 0664);
-+module_param_named(extra_acked_in_startup,
-+ bbr_extra_acked_in_startup, int, 0664);
-+module_param_named(usage_based_cwnd, bbr_usage_based_cwnd, bool, 0664);
-+module_param_named(ecn_enable, bbr_ecn_enable, bool, 0664);
-+
-+static void bbr2_exit_probe_rtt(struct sock *sk);
-+static void bbr2_reset_congestion_signals(struct sock *sk);
-+
-+static void bbr_check_probe_rtt_done(struct sock *sk);
-+
-+/* 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)
-+{
-+ 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)
-+{
-+ 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);
-+}
-+
-+static u64 bbr_rate_kbps(struct sock *sk, u64 rate)
-+{
-+ rate = bbr_bw_bytes_per_sec(sk, rate);
-+ rate *= 8;
-+ do_div(rate, 1000);
-+ return rate;
-+}
-+
-+static u32 bbr_tso_segs_goal(struct sock *sk);
-+static void bbr_debug(struct sock *sk, u32 acked,
-+ const struct rate_sample *rs, struct bbr_context *ctx)
-+{
-+ static const char ca_states[] = {
-+ [TCP_CA_Open] = 'O',
-+ [TCP_CA_Disorder] = 'D',
-+ [TCP_CA_CWR] = 'C',
-+ [TCP_CA_Recovery] = 'R',
-+ [TCP_CA_Loss] = 'L',
-+ };
-+ static const char mode[] = {
-+ 'G', /* Growing - BBR_STARTUP */
-+ 'D', /* Drain - BBR_DRAIN */
-+ 'W', /* Window - BBR_PROBE_BW */
-+ 'M', /* Min RTT - BBR_PROBE_RTT */
-+ };
-+ static const char ack_phase[] = { /* bbr_ack_phase strings */
-+ 'I', /* BBR_ACKS_INIT - 'Init' */
-+ 'R', /* BBR_ACKS_REFILLING - 'Refilling' */
-+ 'B', /* BBR_ACKS_PROBE_STARTING - 'Before' */
-+ 'F', /* BBR_ACKS_PROBE_FEEDBACK - 'Feedback' */
-+ 'A', /* BBR_ACKS_PROBE_STOPPING - 'After' */
-+ };
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ const u32 una = tp->snd_una - bbr->debug.snd_isn;
-+ const u32 fack = tcp_highest_sack_seq(tp);
-+ const u16 dport = ntohs(inet_sk(sk)->inet_dport);
-+ bool is_port_match = (bbr_debug_port_mask &&
-+ ((dport & bbr_debug_port_mask) == 0));
-+ char debugmsg[320];
-+
-+ if (sk->sk_state == TCP_SYN_SENT)
-+ return; /* no bbr_init() yet if SYN retransmit -> CA_Loss */
-+
-+ if (!tp->snd_cwnd || tp->snd_cwnd > bbr_cwnd_warn_val) {
-+ char addr[INET6_ADDRSTRLEN + 10] = { 0 };
-+
-+ if (sk->sk_family == AF_INET)
-+ snprintf(addr, sizeof(addr), "%pI4:%u",
-+ &inet_sk(sk)->inet_daddr, dport);
-+ else if (sk->sk_family == AF_INET6)
-+ snprintf(addr, sizeof(addr), "%pI6:%u",
-+ &sk->sk_v6_daddr, dport);
-+
-+ WARN_ONCE(1,
-+ "BBR %s cwnd alert: %u "
-+ "snd_una: %u ca: %d pacing_gain: %u cwnd_gain: %u "
-+ "bw: %u rtt: %u min_rtt: %u "
-+ "acked: %u tso_segs: %u "
-+ "bw: %d %ld %d pif: %u\n",
-+ addr, tp->snd_cwnd,
-+ una, inet_csk(sk)->icsk_ca_state,
-+ bbr->pacing_gain, bbr->cwnd_gain,
-+ bbr_max_bw(sk), (tp->srtt_us >> 3), bbr->min_rtt_us,
-+ acked, bbr_tso_segs_goal(sk),
-+ rs->delivered, rs->interval_us, rs->is_retrans,
-+ tcp_packets_in_flight(tp));
-+ }
-+
-+ if (likely(!bbr_debug_with_printk && !bbr_debug_ftrace))
-+ return;
-+
-+ if (!sock_flag(sk, SOCK_DBG) && !is_port_match)
-+ return;
-+
-+ if (!ctx->log && !tp->app_limited && !(bbr_flags & FLAG_DEBUG_VERBOSE))
-+ return;
-+
-+ if (ipv4_is_loopback(inet_sk(sk)->inet_daddr) &&
-+ !(bbr_flags & FLAG_DEBUG_LOOPBACK))
-+ return;
-+
-+ snprintf(debugmsg, sizeof(debugmsg) - 1,
-+ "BBR %pI4:%-5u %5u,%03u:%-7u %c "
-+ "%c %2u br %2u cr %2d rtt %5ld d %2d i %5ld mrtt %d %cbw %llu "
-+ "bw %llu lb %llu ib %llu qb %llu "
-+ "a %u if %2u %c %c dl %u l %u al %u # %u t %u %c %c "
-+ "lr %d er %d ea %d bwl %lld il %d ih %d c %d "
-+ "v %d %c %u %c %s\n",
-+ &inet_sk(sk)->inet_daddr, dport,
-+ una / 1000, una % 1000, fack - tp->snd_una,
-+ ca_states[inet_csk(sk)->icsk_ca_state],
-+ bbr->debug.undo ? '@' : mode[bbr->mode],
-+ tp->snd_cwnd,
-+ bbr_extra_acked(sk), /* br (legacy): extra_acked */
-+ rs->tx_in_flight, /* cr (legacy): tx_inflight */
-+ rs->rtt_us,
-+ rs->delivered,
-+ rs->interval_us,
-+ bbr->min_rtt_us,
-+ rs->is_app_limited ? '_' : 'l',
-+ bbr_rate_kbps(sk, ctx->sample_bw), /* lbw: latest sample bw */
-+ bbr_rate_kbps(sk, bbr_max_bw(sk)), /* bw: max bw */
-+ 0ULL, /* lb: [obsolete] */
-+ 0ULL, /* ib: [obsolete] */
-+ div_u64((u64)sk->sk_pacing_rate * 8, 1000),
-+ acked,
-+ tcp_packets_in_flight(tp),
-+ rs->is_ack_delayed ? 'd' : '.',
-+ bbr->round_start ? '*' : '.',
-+ tp->delivered, tp->lost,
-+ tp->app_limited,
-+ 0, /* #: [obsolete] */
-+ ctx->target_cwnd,
-+ tp->reord_seen ? 'r' : '.', /* r: reordering seen? */
-+ ca_states[bbr->prev_ca_state],
-+ (rs->lost + rs->delivered) > 0 ?
-+ (1000 * rs->lost /
-+ (rs->lost + rs->delivered)) : 0, /* lr: loss rate x1000 */
-+ (rs->delivered) > 0 ?
-+ (1000 * rs->delivered_ce /
-+ (rs->delivered)) : 0, /* er: ECN rate x1000 */
-+ 1000 * bbr->ecn_alpha >> BBR_SCALE, /* ea: ECN alpha x1000 */
-+ bbr->bw_lo == ~0U ?
-+ -1 : (s64)bbr_rate_kbps(sk, bbr->bw_lo), /* bwl */
-+ bbr->inflight_lo, /* il */
-+ bbr->inflight_hi, /* ih */
-+ bbr->bw_probe_up_cnt, /* c */
-+ 2, /* v: version */
-+ bbr->debug.event,
-+ bbr->cycle_idx,
-+ ack_phase[bbr->ack_phase],
-+ bbr->bw_probe_samples ? "Y" : "N");
-+ debugmsg[sizeof(debugmsg) - 1] = 0;
-+
-+ /* printk takes a higher precedence. */
-+ if (bbr_debug_with_printk)
-+ printk(KERN_DEBUG "%s", debugmsg);
-+
-+ if (unlikely(bbr->debug.undo))
-+ bbr->debug.undo = 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, sk->sk_max_pacing_rate);
-+ return rate;
-+}
-+
-+/* Initialize pacing rate to: high_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)tp->snd_cwnd * BW_UNIT;
-+ do_div(bw, rtt_us);
-+ sk->sk_pacing_rate = bbr_bw_to_pacing_rate(sk, bw, bbr->params.high_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 > sk->sk_pacing_rate)
-+ sk->sk_pacing_rate = rate;
-+}
-+
-+static u32 bbr_min_tso_segs(struct sock *sk)
-+{
-+ return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2;
-+}
-+
-+/* Return the number of segments BBR would like in a TSO/GSO skb, given
-+ * a particular max gso size as a constraint.
-+ */
-+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 = sk->sk_pacing_rate >> 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->params.tso_rtt_shift) {
-+ r = bbr->min_rtt_us >> bbr->params.tso_rtt_shift;
-+ if (r < BITS_PER_TYPE(u32)) /* prevent undefined behavior */
-+ bytes += GSO_MAX_SIZE >> r;
-+ }
-+
-+ bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER);
-+ segs = max_t(u32, div_u64(bytes, mss_now), bbr_min_tso_segs(sk));
-+ return segs;
-+}
-+
-+/* 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 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_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 = tp->snd_cwnd; /* this cwnd is good enough */
-+ else /* loss recovery or BBR_PROBE_RTT have temporarily cut cwnd */
-+ bbr->prior_cwnd = max(bbr->prior_cwnd, tp->snd_cwnd);
-+}
-+
-+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) {
-+ 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_ecn_enable &&
-+ bbr->params.precise_ece_ack) {
-+ u32 state = bbr->ce_state;
-+ dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state);
-+ bbr->ce_state = state;
-+ if (tp->fast_ack_mode == 2 && event == CA_EVENT_ECN_IS_CE)
-+ tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS);
-+ }
-+}
-+
-+/* 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 (bbr_min_tso_rate) this won't bloat cwnd because
-+ * in such cases tso_segs_goal is 1. 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. */
-+ if (bbr->params.cwnd_tso_budget == 1) {
-+ cwnd = max_t(u32, cwnd, tso_segs_goal);
-+ cwnd = max_t(u32, cwnd, bbr->params.cwnd_min_target);
-+ } else {
-+ cwnd += tso_segs_goal;
-+ cwnd = (cwnd + 1) & ~1U;
-+ }
-+ /* 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)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ u32 max_aggr_cwnd, aggr_cwnd = 0;
-+
-+ if (bbr->params.extra_acked_gain &&
-+ (bbr_full_bw_reached(sk) || bbr->params.extra_acked_in_startup)) {
-+ max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us)
-+ / BW_UNIT;
-+ aggr_cwnd = (bbr->params.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)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+
-+ if (bbr->params.probe_rtt_cwnd_gain == 0)
-+ return bbr->params.cwnd_min_target;
-+ return max_t(u32, bbr->params.cwnd_min_target,
-+ bbr_bdp(sk, bbr_bw(sk), bbr->params.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, prev_cwnd = tp->snd_cwnd, max_probe;
-+
-+ 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);
-+
-+ /* If we're below target cwnd, slow start cwnd toward target cwnd. */
-+ bbr->debug.target_cwnd = 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;
-+ }
-+
-+ /* When growing cwnd, don't grow beyond twice what we just probed. */
-+ if (bbr->params.usage_based_cwnd) {
-+ max_probe = max(2 * tp->max_packets_out, tp->snd_cwnd);
-+ cwnd = min(cwnd, max_probe);
-+ }
-+
-+ cwnd = max_t(u32, cwnd, bbr->params.cwnd_min_target);
-+done:
-+ tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp); /* apply global cap */
-+ if (bbr->mode == BBR_PROBE_RTT) /* drain queue, refresh min_rtt */
-+ tp->snd_cwnd = min_t(u32, tp->snd_cwnd, bbr_probe_rtt_cwnd(sk));
-+
-+ ctx->target_cwnd = target_cwnd;
-+ ctx->log = (tp->snd_cwnd != prev_cwnd);
-+}
-+
-+/* See if we have reached next round trip */
-+static void 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);
-+
-+ 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)) {
-+ bbr->next_rtt_delivered = tp->delivered;
-+ bbr->round_start = 1;
-+ }
-+}
-+
-+/* 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)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ 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;
-+ bbr->debug.rs_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->params.extra_acked_win_rtts;
-+
-+ if (!bbr->params.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->params.extra_acked_in_startup &&
-+ !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, tp->snd_cwnd);
-+ if (extra_acked > bbr->extra_acked[bbr->extra_acked_win_idx])
-+ 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->params.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->params.full_bw_cnt;
-+}
-+
-+/* If pipe is probably full, drain the queue and then enter steady-state. */
-+static bool 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 */
-+ tcp_sk(sk)->snd_ssthresh =
-+ bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+ bbr2_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))
-+ return true; /* exiting DRAIN now */
-+ return false;
-+}
-+
-+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 */
-+ tp->snd_cwnd = max(tp->snd_cwnd, bbr->prior_cwnd);
-+ bbr2_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->params.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->params.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->params.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->params.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->params.high_gain;
-+ bbr->cwnd_gain = bbr->params.startup_cwnd_gain;
-+ break;
-+ case BBR_DRAIN:
-+ bbr->pacing_gain = bbr->params.drain_gain; /* slow, to drain */
-+ bbr->cwnd_gain = bbr->params.startup_cwnd_gain; /* keep cwnd */
-+ break;
-+ case BBR_PROBE_BW:
-+ bbr->pacing_gain = bbr->params.pacing_gain[bbr->cycle_idx];
-+ bbr->cwnd_gain = bbr->params.cwnd_gain;
-+ 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;
-+ }
-+}
-+
-+static void bbr_init(struct sock *sk)
-+{
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ int i;
-+
-+ WARN_ON_ONCE(tp->snd_cwnd >= bbr_cwnd_warn_val);
-+
-+ bbr->initialized = 1;
-+ bbr->params.high_gain = min(0x7FF, bbr_high_gain);
-+ bbr->params.drain_gain = min(0x3FF, bbr_drain_gain);
-+ bbr->params.startup_cwnd_gain = min(0x7FF, bbr_startup_cwnd_gain);
-+ bbr->params.cwnd_gain = min(0x7FF, bbr_cwnd_gain);
-+ bbr->params.cwnd_tso_budget = min(0x1U, bbr_cwnd_tso_budget);
-+ bbr->params.cwnd_min_target = min(0xFU, bbr_cwnd_min_target);
-+ bbr->params.min_rtt_win_sec = min(0x1FU, bbr_min_rtt_win_sec);
-+ bbr->params.probe_rtt_mode_ms = min(0x1FFU, bbr_probe_rtt_mode_ms);
-+ bbr->params.full_bw_cnt = min(0x7U, bbr_full_bw_cnt);
-+ bbr->params.full_bw_thresh = min(0x3FFU, bbr_full_bw_thresh);
-+ bbr->params.extra_acked_gain = min(0x7FF, bbr_extra_acked_gain);
-+ bbr->params.extra_acked_win_rtts = min(0x1FU, bbr_extra_acked_win_rtts);
-+ bbr->params.drain_to_target = bbr_drain_to_target ? 1 : 0;
-+ bbr->params.precise_ece_ack = bbr_precise_ece_ack ? 1 : 0;
-+ bbr->params.extra_acked_in_startup = bbr_extra_acked_in_startup ? 1 : 0;
-+ bbr->params.probe_rtt_cwnd_gain = min(0xFFU, bbr_probe_rtt_cwnd_gain);
-+ bbr->params.probe_rtt_win_ms =
-+ min(0x3FFFU,
-+ min_t(u32, bbr_probe_rtt_win_ms,
-+ bbr->params.min_rtt_win_sec * MSEC_PER_SEC));
-+ for (i = 0; i < CYCLE_LEN; i++)
-+ bbr->params.pacing_gain[i] = min(0x3FF, bbr_pacing_gain[i]);
-+ bbr->params.usage_based_cwnd = bbr_usage_based_cwnd ? 1 : 0;
-+ bbr->params.tso_rtt_shift = min(0xFU, bbr_tso_rtt_shift);
-+
-+ bbr->debug.snd_isn = tp->snd_una;
-+ bbr->debug.target_cwnd = 0;
-+ bbr->debug.undo = 0;
-+
-+ bbr->init_cwnd = min(0x7FU, tp->snd_cwnd);
-+ bbr->prior_cwnd = tp->prior_cwnd;
-+ tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
-+ bbr->next_rtt_delivered = 0;
-+ bbr->prev_ca_state = TCP_CA_Open;
-+ bbr->packet_conservation = 0;
-+
-+ 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->mode = BBR_STARTUP;
-+ bbr->debug.rs_bw = 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;
-+
-+ 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);
-+}
-+
-+static u32 bbr_sndbuf_expand(struct sock *sk)
-+{
-+ /* Provision 3 * cwnd since BBR may slow-start even during recovery. */
-+ return 3;
-+}
-+
-+/* __________________________________________________________________________
-+ *
-+ * Functions new to BBR v2 ("bbr") congestion control are below here.
-+ * __________________________________________________________________________
-+ */
-+
-+/* Incorporate a new bw sample into the current window of our max filter. */
-+static void bbr2_take_bw_hi_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 bbr2_advance_bw_hi_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;
-+}
-+
-+/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */
-+static u32 bbr2_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 bbr2_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 bbr2_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 bbr2_handle_queue_too_high_in_startup(struct sock *sk)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+
-+ bbr->full_bw_reached = 1;
-+ bbr->inflight_hi = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT);
-+}
-+
-+/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */
-+static void bbr2_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->params.full_ecn_cnt || !bbr->params.ecn_thresh)
-+ return;
-+
-+ if (ce_ratio >= bbr->params.ecn_thresh)
-+ bbr->startup_ecn_rounds++;
-+ else
-+ bbr->startup_ecn_rounds = 0;
-+
-+ if (bbr->startup_ecn_rounds >= bbr->params.full_ecn_cnt) {
-+ bbr->debug.event = 'E'; /* ECN caused STARTUP exit */
-+ bbr2_handle_queue_too_high_in_startup(sk);
-+ return;
-+ }
-+}
-+
-+static void bbr2_update_ecn_alpha(struct sock *sk)
-+{
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ s32 delivered, delivered_ce;
-+ u64 alpha, ce_ratio;
-+ u32 gain;
-+
-+ if (bbr->params.ecn_factor == 0)
-+ return;
-+
-+ 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;
-+
-+ /* See if we should use ECN sender logic for this connection. */
-+ if (!bbr->ecn_eligible && bbr_ecn_enable &&
-+ (bbr->min_rtt_us <= bbr->params.ecn_max_rtt_us ||
-+ !bbr->params.ecn_max_rtt_us))
-+ bbr->ecn_eligible = 1;
-+
-+ ce_ratio = (u64)delivered_ce << BBR_SCALE;
-+ do_div(ce_ratio, delivered);
-+ gain = bbr->params.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;
-+
-+ bbr2_check_ecn_too_high_in_startup(sk, ce_ratio);
-+}
-+
-+/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */
-+static void bbr2_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 = tp->snd_cwnd / growth_this_round;
-+ cnt = max(cnt, 1U);
-+ bbr->bw_probe_up_cnt = cnt;
-+ bbr->debug.event = 'G'; /* Grow inflight_hi slope */
-+}
-+
-+/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */
-+static void bbr2_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 || tp->snd_cwnd < bbr->inflight_hi) {
-+ bbr->bw_probe_up_acks = 0; /* don't accmulate unused credits */
-+ 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->debug.event = 'I'; /* Increment inflight_hi */
-+ }
-+
-+ if (bbr->round_start)
-+ bbr2_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,
-+ * which can be used in either v1 or v2, and the PROBE_UP phase of v2, which
-+ * uses it to notice when loss/ECN rates suggest inflight is too high.
-+ */
-+static bool bbr2_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->params.loss_thresh >>
-+ BBR_SCALE;
-+ if (rs->lost > loss_thresh)
-+ return true;
-+ }
-+
-+ if (rs->delivered_ce > 0 && rs->delivered > 0 &&
-+ bbr->ecn_eligible && bbr->params.ecn_thresh) {
-+ ecn_thresh = (u64)rs->delivered * bbr->params.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 bbr2_inflight_hi_from_lost_skb(const struct sock *sk,
-+ const struct rate_sample *rs,
-+ const struct sk_buff *skb)
-+{
-+ const struct bbr *bbr = inet_csk_ca(sk);
-+ u32 loss_thresh = bbr->params.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 (WARN_ONCE(inflight_prev < 0,
-+ "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_ON_ONCE(lost_prev < 0))
-+ 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 bbr2_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->params.inflight_headroom;
-+ headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE;
-+ headroom = max(headroom, 1U);
-+ return max_t(s32, bbr->inflight_hi - headroom,
-+ bbr->params.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 bbr2_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 = bbr2_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->params.cwnd_min_target);
-+ tp->snd_cwnd = min(cap, tp->snd_cwnd);
-+}
-+
-+/* 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 bbr2_adapt_lower_bounds(struct sock *sk)
-+{
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ u32 ecn_cut, ecn_inflight_lo, beta;
-+
-+ /* We only use lower-bound estimates when not probing bw.
-+ * When probing we need to push inflight higher to probe bw.
-+ */
-+ if (bbr2_is_probing_bandwidth(sk))
-+ return;
-+
-+ /* ECN response. */
-+ if (bbr->ecn_in_round && bbr->ecn_eligible && bbr->params.ecn_factor) {
-+ /* Reduce inflight to (1 - alpha*ecn_factor). */
-+ ecn_cut = (BBR_UNIT -
-+ ((bbr->ecn_alpha * bbr->params.ecn_factor) >>
-+ BBR_SCALE));
-+ if (bbr->inflight_lo == ~0U)
-+ bbr->inflight_lo = tp->snd_cwnd;
-+ ecn_inflight_lo = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE;
-+ } else {
-+ ecn_inflight_lo = ~0U;
-+ }
-+
-+ /* Loss response. */
-+ if (bbr->loss_in_round) {
-+ /* Reduce bw and inflight to (1 - beta). */
-+ if (bbr->bw_lo == ~0U)
-+ bbr->bw_lo = bbr_max_bw(sk);
-+ if (bbr->inflight_lo == ~0U)
-+ bbr->inflight_lo = tp->snd_cwnd;
-+ beta = bbr->params.beta;
-+ bbr->bw_lo =
-+ max_t(u32, bbr->bw_latest,
-+ (u64)bbr->bw_lo *
-+ (BBR_UNIT - beta) >> BBR_SCALE);
-+ bbr->inflight_lo =
-+ max_t(u32, bbr->inflight_latest,
-+ (u64)bbr->inflight_lo *
-+ (BBR_UNIT - beta) >> BBR_SCALE);
-+ }
-+
-+ /* Adjust to the lower of the levels implied by loss or ECN. */
-+ bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo);
-+}
-+
-+/* Reset any short-term lower-bound adaptation to congestion, so that we can
-+ * push our inflight up.
-+ */
-+static void bbr2_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 bbr2_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;
-+}
-+
-+/* 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 bbr2_update_congestion_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);
-+ u64 bw;
-+
-+ bbr->loss_round_start = 0;
-+ 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))
-+ bbr2_take_bw_hi_sample(sk, bw);
-+
-+ bbr->loss_in_round |= (rs->losses > 0);
-+
-+ /* Update rate and volume of delivered data from latest round trip: */
-+ 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))
-+ return; /* skip the per-round-trip updates */
-+ /* Now do per-round-trip updates. */
-+ bbr->loss_round_delivered = tp->delivered; /* mark round trip */
-+ bbr->loss_round_start = 1;
-+ bbr2_adapt_lower_bounds(sk);
-+
-+ /* Update windowed "latest" (single-round-trip) filters. */
-+ bbr->loss_in_round = 0;
-+ bbr->ecn_in_round = 0;
-+ bbr->bw_latest = ctx->sample_bw;
-+ bbr->inflight_latest = rs->delivered;
-+}
-+
-+/* 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 bbr2_is_reno_coexistence_probe_time(struct sock *sk)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ u32 inflight, rounds, reno_gain, reno_rounds;
-+
-+ /* Random loss can shave some small percentage off of our inflight
-+ * in each round. To survive this, flows need robust periodic probes.
-+ */
-+ rounds = bbr->params.bw_probe_max_rounds;
-+
-+ reno_gain = bbr->params.bw_probe_reno_gain;
-+ if (reno_gain) {
-+ inflight = bbr2_target_inflight(sk);
-+ reno_rounds = ((u64)inflight * reno_gain) >> BBR_SCALE;
-+ rounds = min(rounds, reno_rounds);
-+ }
-+ 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 bbr2_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->params.bw_probe_rand_rounds);
-+ /* Decide the random wall clock bound for wait until probe: */
-+ bbr->probe_wait_us = bbr->params.bw_probe_base_us +
-+ get_random_u32_below(bbr->params.bw_probe_rand_us);
-+}
-+
-+static void bbr2_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 bbr2_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);
-+
-+ bbr2_reset_lower_bounds(sk);
-+ if (bbr->inflight_hi != ~0U)
-+ bbr->inflight_hi += bbr->params.refill_add_inc;
-+ 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;
-+ bbr2_set_cycle_idx(sk, BBR_BW_PROBE_REFILL);
-+}
-+
-+/* Now probe max deliverable data rate and volume. */
-+static void bbr2_start_bw_probe_up(struct sock *sk)
-+{
-+ 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;
-+ bbr2_set_cycle_idx(sk, BBR_BW_PROBE_UP);
-+ bbr2_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 bbr2_start_bw_probe_down(struct sock *sk)
-+{
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ struct bbr *bbr = inet_csk_ca(sk);
-+
-+ bbr2_reset_congestion_signals(sk);
-+ bbr->bw_probe_up_cnt = ~0U; /* not growing inflight_hi any more */
-+ bbr2_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;
-+ bbr2_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 bbr2_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);
-+
-+ bbr2_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 bbr2_handle_inflight_too_high(struct sock *sk,
-+ const struct rate_sample *rs)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ const u32 beta = bbr->params.beta;
-+
-+ bbr->prev_probe_too_high = 1;
-+ bbr->bw_probe_samples = 0; /* only react once per probe */
-+ bbr->debug.event = 'L'; /* Loss/ECN too high */
-+ /* 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)bbr2_target_inflight(sk) *
-+ (BBR_UNIT - beta) >> BBR_SCALE);
-+ if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP)
-+ bbr2_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 bbr2_adapt_upper_bounds(struct sock *sk,
-+ const struct rate_sample *rs)
-+{
-+ 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)
-+ bbr2_advance_bw_hi_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->debug.event = 'R'; /* reprobe */
-+ bbr2_start_bw_probe_refill(sk, 0);
-+ return true; /* yes, decided state transition */
-+ }
-+ }
-+
-+ if (bbr2_is_inflight_too_high(sk, rs)) {
-+ if (bbr->bw_probe_samples) /* sample is from bw probing? */
-+ bbr2_handle_inflight_too_high(sk, rs);
-+ } else {
-+ /* Loss/ECN rate is declared safe. Adjust upper bound upward. */
-+ if (bbr->inflight_hi == ~0U) /* no excess queue signals yet? */
-+ return false;
-+
-+ /* To be resilient to random loss, we must raise 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;
-+ bbr->debug.event = 'U'; /* raise up inflight_hi */
-+ }
-+
-+ if (bbr->mode == BBR_PROBE_BW &&
-+ bbr->cycle_idx == BBR_BW_PROBE_UP)
-+ bbr2_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 bbr2_check_time_to_probe_bw(struct sock *sk)
-+{
-+ 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 a burst of cross-traffic has ceased and freed up bw,
-+ * or in case we are sharing with multiplicatively probing traffic).
-+ */
-+ if (bbr->params.ecn_reprobe_gain && bbr->ecn_eligible &&
-+ bbr->ecn_in_cycle && !bbr->loss_in_cycle &&
-+ inet_csk(sk)->icsk_ca_state == TCP_CA_Open) {
-+ bbr->debug.event = 'A'; /* *A*ll clear to probe *A*gain */
-+ /* Calculate n so that when bbr2_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->params.ecn_reprobe_gain) >> BBR_SCALE));
-+ bbr2_start_bw_probe_refill(sk, n);
-+ return true;
-+ }
-+
-+ if (bbr2_has_elapsed_in_phase(sk, bbr->probe_wait_us) ||
-+ bbr2_is_reno_coexistence_probe_time(sk)) {
-+ bbr2_start_bw_probe_refill(sk, 0);
-+ return true;
-+ }
-+ return false;
-+}
-+
-+/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */
-+static bool bbr2_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ bool is_under_bdp, is_long_enough;
-+
-+ /* Always need to pull inflight down to leave headroom in queue. */
-+ if (inflight > bbr2_inflight_with_headroom(sk))
-+ return false;
-+
-+ is_under_bdp = inflight <= bbr_inflight(sk, bw, BBR_UNIT);
-+ if (bbr->params.drain_to_target)
-+ return is_under_bdp;
-+
-+ is_long_enough = bbr2_has_elapsed_in_phase(sk, bbr->min_rtt_us);
-+ return is_under_bdp || is_long_enough;
-+}
-+
-+/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */
-+static void bbr2_update_cycle_phase(struct sock *sk,
-+ const struct rate_sample *rs)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+ bool is_risky = false, is_queuing = false;
-+ u32 inflight, bw;
-+
-+ if (!bbr_full_bw_reached(sk))
-+ return;
-+
-+ /* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */
-+ if (bbr2_adapt_upper_bounds(sk, rs))
-+ 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 (bbr2_check_time_to_probe_bw(sk))
-+ 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;
-+ bbr2_start_bw_probe_up(sk);
-+ }
-+ 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.
-+ * (checked here)
-+ * (2) We have probed for at least 1*min_rtt_us, and the
-+ * estimated queue is high enough (inflight > 1.25 * estimated_bdp).
-+ * (checked here)
-+ * (3) Loss filter says loss rate is "too high".
-+ * (checked in bbr_is_inflight_too_high())
-+ * (4) ECN filter says ECN mark rate is "too high".
-+ * (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_risky = true;
-+ bbr->debug.event = 'D'; /* D for danger */
-+ } else if (bbr2_has_elapsed_in_phase(sk, bbr->min_rtt_us) &&
-+ inflight >=
-+ bbr_inflight(sk, bw,
-+ bbr->params.bw_probe_pif_gain)) {
-+ is_queuing = true;
-+ bbr->debug.event = 'Q'; /* building Queue */
-+ }
-+ if (is_risky || is_queuing) {
-+ bbr->prev_probe_too_high = 0; /* no loss/ECN (yet) */
-+ bbr2_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 (bbr2_check_time_to_probe_bw(sk))
-+ return; /* already decided state transition */
-+ if (bbr2_check_time_to_cruise(sk, inflight, bw))
-+ bbr2_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 bbr2_exit_probe_rtt(struct sock *sk)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+
-+ bbr2_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.
-+ */
-+ bbr2_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.
-+ */
-+ bbr2_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 bbr2_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->params.full_loss_cnt && bbr->loss_round_start &&
-+ inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery &&
-+ bbr->loss_events_in_round >= bbr->params.full_loss_cnt &&
-+ bbr2_is_inflight_too_high(sk, rs)) {
-+ bbr->debug.event = 'P'; /* Packet loss caused STARTUP exit */
-+ bbr2_handle_queue_too_high_in_startup(sk);
-+ return;
-+ }
-+ if (bbr->loss_round_start)
-+ bbr->loss_events_in_round = 0;
-+}
-+
-+/* If we are done draining, advance into steady state operation in PROBE_BW. */
-+static void bbr2_check_drain(struct sock *sk, const struct rate_sample *rs,
-+ struct bbr_context *ctx)
-+{
-+ struct bbr *bbr = inet_csk_ca(sk);
-+
-+ if (bbr_check_drain(sk, rs, ctx)) {
-+ bbr->mode = BBR_PROBE_BW;
-+ bbr2_start_bw_probe_down(sk);
-+ }
-+}
-+
-+static void bbr2_update_model(struct sock *sk, const struct rate_sample *rs,
-+ struct bbr_context *ctx)
-+{
-+ bbr2_update_congestion_signals(sk, rs, ctx);
-+ bbr_update_ack_aggregation(sk, rs);
-+ bbr2_check_loss_too_high_in_startup(sk, rs);
-+ bbr_check_full_bw_reached(sk, rs);
-+ bbr2_check_drain(sk, rs, ctx);
-+ bbr2_update_cycle_phase(sk, rs);
-+ 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 bbr2_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->params.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;
-+ bbr2_check_drain(sk, rs, ctx);
-+ bbr2_update_cycle_phase(sk, rs);
-+ 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 bbr2_main(struct sock *sk, 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;
-+
-+ bbr->debug.event = '.'; /* init to default NOP (no event yet) */
-+
-+ bbr_update_round_start(sk, rs, &ctx);
-+ if (bbr->round_start) {
-+ bbr->rounds_since_probe =
-+ min_t(s32, bbr->rounds_since_probe + 1, 0xFF);
-+ bbr2_update_ecn_alpha(sk);
-+ }
-+
-+ bbr->ecn_in_round |= rs->is_ece;
-+ bbr_calculate_bw_sample(sk, rs, &ctx);
-+
-+ if (bbr2_fast_path(sk, &update_model, rs, &ctx))
-+ goto out;
-+
-+ if (update_model)
-+ bbr2_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,
-+ tp->snd_cwnd, &ctx);
-+ bbr2_bound_cwnd_for_inflight_model(sk);
-+
-+out:
-+ 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;
-+
-+ bbr_debug(sk, rs->acked_sacked, rs, &ctx);
-+}
-+
-+/* Module parameters that are settable by TCP_CONGESTION_PARAMS are declared
-+ * down here, so that the algorithm functions that use the parameters must use
-+ * the per-socket parameters; if they accidentally use the global version
-+ * then there will be a compile error.
-+ * TODO(ncardwell): move all per-socket parameters down to this section.
-+ */
-+
-+/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE.
-+ * No loss response when 0. Max allwed value is 255.
-+ */
-+static u32 bbr_beta = BBR_UNIT * 30 / 100;
-+
-+/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE.
-+ * Max allowed value is 255.
-+ */
-+static u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16; /* 1/16 = 6.25% */
-+
-+/* The initial value for the ecn_alpha state variable. Default and max
-+ * BBR_UNIT (256), representing 1.0. This allows a flow to respond quickly
-+ * to congestion if the bottleneck is congested when the flow starts up.
-+ */
-+static u32 bbr_ecn_alpha_init = BBR_UNIT; /* 1.0, to respond quickly */
-+
-+/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE.
-+ * No ECN based bounding when 0. Max allwed value is 255.
-+ */
-+static 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. Max allowed is 255.
-+ */
-+static u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2; /* 1/2 = 50% */
-+
-+/* Max RTT (in usec) at which to use sender-side ECN logic.
-+ * Disabled when 0 (ECN allowed at any RTT).
-+ * Max allowed for the parameter is 524287 (0x7ffff) us, ~524 ms.
-+ */
-+static u32 bbr_ecn_max_rtt_us = 5000;
-+
-+/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN
-+ * clears then use a multiplicative increase to quickly reprobe bw by
-+ * starting inflight probing at the given multiple of inflight_hi.
-+ * Default for this experimental knob is 0 (disabled).
-+ * Planned value for experiments: BBR_UNIT * 1 / 2 = 128, representing 0.5.
-+ */
-+static u32 bbr_ecn_reprobe_gain;
-+
-+/* Estimate bw probing has gone too far if loss rate exceeds this level. */
-+static u32 bbr_loss_thresh = BBR_UNIT * 2 / 100; /* 2% loss */
-+
-+/* 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. Max allowed value is 15 (0xF).
-+ */
-+static u32 bbr_full_loss_cnt = 8;
-+
-+/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh
-+ * meets this count. Max allowed value is 3.
-+ */
-+static u32 bbr_full_ecn_cnt = 2;
-+
-+/* Fraction of unutilized headroom to try to leave in path upon high loss. */
-+static u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100;
-+
-+/* Multiplier to get target inflight (as multiple of BDP) for PROBE_UP phase.
-+ * Default is 1.25x, as in BBR v1. Max allowed is 511.
-+ */
-+static u32 bbr_bw_probe_pif_gain = BBR_UNIT * 5 / 4;
-+
-+/* Multiplier to get Reno-style probe epoch duration as: k * BDP round trips.
-+ * If zero, disables this BBR v2 Reno-style BDP-scaled coexistence mechanism.
-+ * Max allowed is 511.
-+ */
-+static u32 bbr_bw_probe_reno_gain = BBR_UNIT;
-+
-+/* 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 u32 bbr_bw_probe_max_rounds = 63;
-+
-+/* Max amount of randomness to inject in round counting for Reno-coexistence.
-+ * Max value is 15.
-+ */
-+static 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 u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC; /* 2 secs */
-+
-+/* Use BBR-native probes spread over this many usec: */
-+static u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC; /* 1 secs */
-+
-+/* Undo the model changes made in loss recovery if recovery was spurious? */
-+static bool bbr_undo = true;
-+
-+/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */
-+static bool bbr_fast_path = true; /* default: enabled */
-+
-+/* Use fast ack mode ? */
-+static int bbr_fast_ack_mode = 1; /* default: rwnd check off */
-+
-+/* How much to additively increase inflight_hi when entering REFILL? */
-+static u32 bbr_refill_add_inc; /* default: disabled */
-+
-+module_param_named(beta, bbr_beta, uint, 0644);
-+module_param_named(ecn_alpha_gain, bbr_ecn_alpha_gain, uint, 0644);
-+module_param_named(ecn_alpha_init, bbr_ecn_alpha_init, uint, 0644);
-+module_param_named(ecn_factor, bbr_ecn_factor, uint, 0644);
-+module_param_named(ecn_thresh, bbr_ecn_thresh, uint, 0644);
-+module_param_named(ecn_max_rtt_us, bbr_ecn_max_rtt_us, uint, 0644);
-+module_param_named(ecn_reprobe_gain, bbr_ecn_reprobe_gain, uint, 0644);
-+module_param_named(loss_thresh, bbr_loss_thresh, uint, 0664);
-+module_param_named(full_loss_cnt, bbr_full_loss_cnt, uint, 0664);
-+module_param_named(full_ecn_cnt, bbr_full_ecn_cnt, uint, 0664);
-+module_param_named(inflight_headroom, bbr_inflight_headroom, uint, 0664);
-+module_param_named(bw_probe_pif_gain, bbr_bw_probe_pif_gain, uint, 0664);
-+module_param_named(bw_probe_reno_gain, bbr_bw_probe_reno_gain, uint, 0664);
-+module_param_named(bw_probe_max_rounds, bbr_bw_probe_max_rounds, uint, 0664);
-+module_param_named(bw_probe_rand_rounds, bbr_bw_probe_rand_rounds, uint, 0664);
-+module_param_named(bw_probe_base_us, bbr_bw_probe_base_us, uint, 0664);
-+module_param_named(bw_probe_rand_us, bbr_bw_probe_rand_us, uint, 0664);
-+module_param_named(undo, bbr_undo, bool, 0664);
-+module_param_named(fast_path, bbr_fast_path, bool, 0664);
-+module_param_named(fast_ack_mode, bbr_fast_ack_mode, uint, 0664);
-+module_param_named(refill_add_inc, bbr_refill_add_inc, uint, 0664);
-+
-+static void bbr2_init(struct sock *sk)
-+{
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ struct bbr *bbr = inet_csk_ca(sk);
-+
-+ bbr_init(sk); /* run shared init code for v1 and v2 */
-+
-+ /* BBR v2 parameters: */
-+ bbr->params.beta = min_t(u32, 0xFFU, bbr_beta);
-+ bbr->params.ecn_alpha_gain = min_t(u32, 0xFFU, bbr_ecn_alpha_gain);
-+ bbr->params.ecn_alpha_init = min_t(u32, BBR_UNIT, bbr_ecn_alpha_init);
-+ bbr->params.ecn_factor = min_t(u32, 0xFFU, bbr_ecn_factor);
-+ bbr->params.ecn_thresh = min_t(u32, 0xFFU, bbr_ecn_thresh);
-+ bbr->params.ecn_max_rtt_us = min_t(u32, 0x7ffffU, bbr_ecn_max_rtt_us);
-+ bbr->params.ecn_reprobe_gain = min_t(u32, 0x1FF, bbr_ecn_reprobe_gain);
-+ bbr->params.loss_thresh = min_t(u32, 0xFFU, bbr_loss_thresh);
-+ bbr->params.full_loss_cnt = min_t(u32, 0xFU, bbr_full_loss_cnt);
-+ bbr->params.full_ecn_cnt = min_t(u32, 0x3U, bbr_full_ecn_cnt);
-+ bbr->params.inflight_headroom =
-+ min_t(u32, 0xFFU, bbr_inflight_headroom);
-+ bbr->params.bw_probe_pif_gain =
-+ min_t(u32, 0x1FFU, bbr_bw_probe_pif_gain);
-+ bbr->params.bw_probe_reno_gain =
-+ min_t(u32, 0x1FFU, bbr_bw_probe_reno_gain);
-+ bbr->params.bw_probe_max_rounds =
-+ min_t(u32, 0xFFU, bbr_bw_probe_max_rounds);
-+ bbr->params.bw_probe_rand_rounds =
-+ min_t(u32, 0xFU, bbr_bw_probe_rand_rounds);
-+ bbr->params.bw_probe_base_us =
-+ min_t(u32, (1 << 26) - 1, bbr_bw_probe_base_us);
-+ bbr->params.bw_probe_rand_us =
-+ min_t(u32, (1 << 26) - 1, bbr_bw_probe_rand_us);
-+ bbr->params.undo = bbr_undo;
-+ bbr->params.fast_path = bbr_fast_path ? 1 : 0;
-+ bbr->params.refill_add_inc = min_t(u32, 0x3U, bbr_refill_add_inc);
-+
-+ /* BBR v2 state: */
-+ bbr->initialized = 1;
-+ /* 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;
-+ bbr2_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->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->params.ecn_alpha_init;
-+ bbr->alpha_last_delivered = 0;
-+ bbr->alpha_last_delivered_ce = 0;
-+
-+ tp->fast_ack_mode = min_t(u32, 0x2U, bbr_fast_ack_mode);
-+
-+ if ((tp->ecn_flags & TCP_ECN_OK) && bbr_ecn_enable)
-+ tp->ecn_flags |= TCP_ECN_ECT_PERMANENT;
-+}
-+
-+/* Core TCP stack informs us that the given skb was just marked lost. */
-+static void bbr2_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;
-+
-+ /* Capture "current" data over the full round trip of loss,
-+ * to have a better chance to see 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;
-+
-+ 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.
-+ */
-+ memset(&rs, 0, sizeof(rs));
-+ 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 (bbr2_is_inflight_too_high(sk, &rs)) {
-+ rs.tx_in_flight = bbr2_inflight_hi_from_lost_skb(sk, &rs, skb);
-+ bbr2_handle_inflight_too_high(sk, &rs);
-+ }
-+}
-+
-+/* Revert short-term model if current loss recovery event was spurious. */
-+static u32 bbr2_undo_cwnd(struct sock *sk)
-+{
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ struct bbr *bbr = inet_csk_ca(sk);
-+
-+ bbr->debug.undo = 1;
-+ bbr->full_bw = 0; /* spurious slow-down; reset full pipe detection */
-+ bbr->full_bw_cnt = 0;
-+ bbr->loss_in_round = 0;
-+
-+ if (!bbr->params.undo)
-+ return tp->snd_cwnd;
-+
-+ /* 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);
-+ return bbr->prior_cwnd;
-+}
-+
-+/* Entering loss recovery, so save state for when we undo recovery. */
-+static u32 bbr2_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_bbr2_phase bbr2_get_phase(struct bbr *bbr)
-+{
-+ switch (bbr->mode) {
-+ case BBR_STARTUP:
-+ return BBR2_PHASE_STARTUP;
-+ case BBR_DRAIN:
-+ return BBR2_PHASE_DRAIN;
-+ case BBR_PROBE_BW:
-+ break;
-+ case BBR_PROBE_RTT:
-+ return BBR2_PHASE_PROBE_RTT;
-+ default:
-+ return BBR2_PHASE_INVALID;
-+ }
-+ switch (bbr->cycle_idx) {
-+ case BBR_BW_PROBE_UP:
-+ return BBR2_PHASE_PROBE_BW_UP;
-+ case BBR_BW_PROBE_DOWN:
-+ return BBR2_PHASE_PROBE_BW_DOWN;
-+ case BBR_BW_PROBE_CRUISE:
-+ return BBR2_PHASE_PROBE_BW_CRUISE;
-+ case BBR_BW_PROBE_REFILL:
-+ return BBR2_PHASE_PROBE_BW_REFILL;
-+ default:
-+ return BBR2_PHASE_INVALID;
-+ }
-+}
-+
-+static size_t bbr2_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);
-+
-+ memset(&info->bbr2, 0, sizeof(info->bbr2));
-+ info->bbr2.bbr_bw_lsb = (u32)bw;
-+ info->bbr2.bbr_bw_msb = (u32)(bw >> 32);
-+ info->bbr2.bbr_min_rtt = bbr->min_rtt_us;
-+ info->bbr2.bbr_pacing_gain = bbr->pacing_gain;
-+ info->bbr2.bbr_cwnd_gain = bbr->cwnd_gain;
-+ info->bbr2.bbr_bw_hi_lsb = (u32)bw_hi;
-+ info->bbr2.bbr_bw_hi_msb = (u32)(bw_hi >> 32);
-+ info->bbr2.bbr_bw_lo_lsb = (u32)bw_lo;
-+ info->bbr2.bbr_bw_lo_msb = (u32)(bw_lo >> 32);
-+ info->bbr2.bbr_mode = bbr->mode;
-+ info->bbr2.bbr_phase = (__u8)bbr2_get_phase(bbr);
-+ info->bbr2.bbr_version = (__u8)2;
-+ info->bbr2.bbr_inflight_lo = bbr->inflight_lo;
-+ info->bbr2.bbr_inflight_hi = bbr->inflight_hi;
-+ info->bbr2.bbr_extra_acked = bbr_extra_acked(sk);
-+ *attr = INET_DIAG_BBRINFO;
-+ return sizeof(info->bbr2);
-+ }
-+ return 0;
-+}
-+
-+static void bbr2_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 };
-+ struct bbr_context ctx = { 0 };
-+
-+ bbr->prev_ca_state = TCP_CA_Loss;
-+ bbr->full_bw = 0;
-+ if (!bbr2_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(tp->snd_cwnd, bbr->prior_cwnd);
-+ }
-+ bbr_debug(sk, 0, &rs, &ctx);
-+ } else if (bbr->prev_ca_state == TCP_CA_Loss &&
-+ new_state != TCP_CA_Loss) {
-+ tp->snd_cwnd = max(tp->snd_cwnd, bbr->prior_cwnd);
-+ bbr->try_fast_path = 0; /* bound cwnd using latest model */
-+ }
-+}
-+
-+static struct tcp_congestion_ops tcp_bbr2_cong_ops __read_mostly = {
-+ .flags = TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS,
-+ .name = "bbr2",
-+ .owner = THIS_MODULE,
-+ .init = bbr2_init,
-+ .cong_control = bbr2_main,
-+ .sndbuf_expand = bbr_sndbuf_expand,
-+ .skb_marked_lost = bbr2_skb_marked_lost,
-+ .undo_cwnd = bbr2_undo_cwnd,
-+ .cwnd_event = bbr_cwnd_event,
-+ .ssthresh = bbr2_ssthresh,
-+ .tso_segs = bbr_tso_segs,
-+ .get_info = bbr2_get_info,
-+ .set_state = bbr2_set_state,
-+};
-+
-+static int __init bbr_register(void)
-+{
-+ BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE);
-+ return tcp_register_congestion_control(&tcp_bbr2_cong_ops);
-+}
-+
-+static void __exit bbr_unregister(void)
-+{
-+ tcp_unregister_congestion_control(&tcp_bbr2_cong_ops);
-+}
-+
-+module_init(bbr_register);
-+module_exit(bbr_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_LICENSE("Dual BSD/GPL");
-+MODULE_DESCRIPTION("TCP BBR (Bottleneck Bandwidth and RTT)");
-diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
-index d3cae40749e8..0f268f2ff2e9 100644
---- a/net/ipv4/tcp_cong.c
-+++ b/net/ipv4/tcp_cong.c
-@@ -189,6 +189,7 @@ void tcp_init_congestion_control(struct sock *sk)
- struct inet_connection_sock *icsk = inet_csk(sk);
-
- tcp_sk(sk)->prior_ssthresh = 0;
-+ tcp_sk(sk)->fast_ack_mode = 0;
- if (icsk->icsk_ca_ops->init)
- icsk->icsk_ca_ops->init(sk);
- if (tcp_ca_needs_ecn(sk))
-diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
-index 0640453fce54..8a455eb0c552 100644
---- a/net/ipv4/tcp_input.c
-+++ b/net/ipv4/tcp_input.c
-@@ -349,7 +349,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb)
- tcp_enter_quickack_mode(sk, 2);
- break;
- case INET_ECN_CE:
-- if (tcp_ca_needs_ecn(sk))
-+ if (tcp_ca_wants_ce_events(sk))
- tcp_ca_event(sk, CA_EVENT_ECN_IS_CE);
-
- if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) {
-@@ -360,7 +360,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb)
- tp->ecn_flags |= TCP_ECN_SEEN;
- break;
- default:
-- if (tcp_ca_needs_ecn(sk))
-+ if (tcp_ca_wants_ce_events(sk))
- tcp_ca_event(sk, CA_EVENT_ECN_NO_CE);
- tp->ecn_flags |= TCP_ECN_SEEN;
- break;
-@@ -1079,7 +1079,12 @@ static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb)
- */
- static void tcp_notify_skb_loss_event(struct tcp_sock *tp, const struct sk_buff *skb)
- {
-+ struct sock *sk = (struct sock *)tp;
-+ const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
-+
- tp->lost += tcp_skb_pcount(skb);
-+ if (ca_ops->skb_marked_lost)
-+ ca_ops->skb_marked_lost(sk, skb);
- }
-
- void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb)
-@@ -1460,6 +1465,17 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
- WARN_ON_ONCE(tcp_skb_pcount(skb) < pcount);
- tcp_skb_pcount_add(skb, -pcount);
-
-+ /* Adjust tx.in_flight as pcount is shifted from skb to prev. */
-+ if (WARN_ONCE(TCP_SKB_CB(skb)->tx.in_flight < pcount,
-+ "prev in_flight: %u skb in_flight: %u pcount: %u",
-+ TCP_SKB_CB(prev)->tx.in_flight,
-+ TCP_SKB_CB(skb)->tx.in_flight,
-+ pcount))
-+ TCP_SKB_CB(skb)->tx.in_flight = 0;
-+ else
-+ TCP_SKB_CB(skb)->tx.in_flight -= pcount;
-+ TCP_SKB_CB(prev)->tx.in_flight += pcount;
-+
- /* When we're adding to gso_segs == 1, gso_size will be zero,
- * in theory this shouldn't be necessary but as long as DSACK
- * code can come after this skb later on it's better to keep
-@@ -3812,6 +3828,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
-
- prior_fack = tcp_is_sack(tp) ? tcp_highest_sack_seq(tp) : tp->snd_una;
- rs.prior_in_flight = tcp_packets_in_flight(tp);
-+ tcp_rate_check_app_limited(sk);
-
- /* ts_recent update must be made after we are sure that the packet
- * is in window.
-@@ -3910,6 +3927,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
- delivered = tcp_newly_delivered(sk, delivered, flag);
- lost = tp->lost - lost; /* freshly marked lost */
- rs.is_ack_delayed = !!(flag & FLAG_ACK_MAYBE_DELAYED);
-+ rs.is_ece = !!(flag & FLAG_ECE);
- tcp_rate_gen(sk, delivered, lost, is_sack_reneg, sack_state.rate);
- tcp_cong_control(sk, ack, delivered, flag, sack_state.rate);
- tcp_xmit_recovery(sk, rexmit);
-@@ -5509,13 +5527,14 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
-
- /* More than one full frame received... */
- if (((tp->rcv_nxt - tp->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss &&
-+ (tp->fast_ack_mode == 1 ||
- /* ... and right edge of window advances far enough.
- * (tcp_recvmsg() will send ACK otherwise).
- * If application uses SO_RCVLOWAT, we want send ack now if
- * we have not received enough bytes to satisfy the condition.
- */
-- (tp->rcv_nxt - tp->copied_seq < sk->sk_rcvlowat ||
-- __tcp_select_window(sk) >= tp->rcv_wnd)) ||
-+ (tp->rcv_nxt - tp->copied_seq < sk->sk_rcvlowat ||
-+ __tcp_select_window(sk) >= tp->rcv_wnd))) ||
- /* We ACK each frame or... */
- tcp_in_quickack_mode(sk) ||
- /* Protocol state mandates a one-time immediate ACK */
-diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
-index c69f4d966024..a9ceec2702b2 100644
---- a/net/ipv4/tcp_output.c
-+++ b/net/ipv4/tcp_output.c
-@@ -375,7 +375,8 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb,
- th->cwr = 1;
- skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
- }
-- } else if (!tcp_ca_needs_ecn(sk)) {
-+ } else if (!(tp->ecn_flags & TCP_ECN_ECT_PERMANENT) &&
-+ !tcp_ca_needs_ecn(sk)) {
- /* ACK or retransmitted segment: clear ECT|CE */
- INET_ECN_dontxmit(sk);
- }
-@@ -1533,7 +1533,7 @@
- {
- struct tcp_sock *tp = tcp_sk(sk);
- struct sk_buff *buff;
-- int old_factor;
-+ int old_factor, inflight_prev;
- long limit;
- int nlen;
- u8 flags;
-@@ -1610,6 +1611,15 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
-
- if (diff)
- tcp_adjust_pcount(sk, skb, diff);
-+
-+ /* Set buff tx.in_flight as if buff were sent by itself. */
-+ inflight_prev = TCP_SKB_CB(skb)->tx.in_flight - old_factor;
-+ if (WARN_ONCE(inflight_prev < 0,
-+ "inconsistent: tx.in_flight: %u old_factor: %d",
-+ TCP_SKB_CB(skb)->tx.in_flight, old_factor))
-+ inflight_prev = 0;
-+ TCP_SKB_CB(buff)->tx.in_flight = inflight_prev +
-+ tcp_skb_pcount(buff);
- }
-
- /* Link BUFF into the send queue. */
-@@ -1993,13 +2003,12 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
- static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now)
- {
- const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
-- u32 min_tso, tso_segs;
--
-- min_tso = ca_ops->min_tso_segs ?
-- ca_ops->min_tso_segs(sk) :
-- READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs);
-+ u32 tso_segs;
-
-- tso_segs = tcp_tso_autosize(sk, mss_now, min_tso);
-+ tso_segs = ca_ops->tso_segs ?
-+ ca_ops->tso_segs(sk, mss_now) :
-+ tcp_tso_autosize(sk, mss_now,
-+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs));
- return min_t(u32, tso_segs, sk->sk_gso_max_segs);
- }
-
-@@ -2635,6 +2644,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
- skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true);
- list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
- tcp_init_tso_segs(skb, mss_now);
-+ tcp_set_tx_in_flight(sk, skb);
- goto repair; /* Skip network transmission */
- }
-
-diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
-index a8f6d9d06f2e..a8b4c9504570 100644
---- a/net/ipv4/tcp_rate.c
-+++ b/net/ipv4/tcp_rate.c
-@@ -34,6 +34,24 @@
- * ready to send in the write queue.
- */
-
-+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb)
-+{
-+ struct tcp_sock *tp = tcp_sk(sk);
-+ u32 in_flight;
-+
-+ /* Check, sanitize, and record packets in flight after skb was sent. */
-+ in_flight = tcp_packets_in_flight(tp) + tcp_skb_pcount(skb);
-+ if (WARN_ONCE(in_flight > TCPCB_IN_FLIGHT_MAX,
-+ "insane in_flight %u cc %s mss %u "
-+ "cwnd %u pif %u %u %u %u\n",
-+ in_flight, inet_csk(sk)->icsk_ca_ops->name,
-+ tp->mss_cache, tp->snd_cwnd,
-+ tp->packets_out, tp->retrans_out,
-+ tp->sacked_out, tp->lost_out))
-+ in_flight = TCPCB_IN_FLIGHT_MAX;
-+ TCP_SKB_CB(skb)->tx.in_flight = in_flight;
-+}
-+
- /* Snapshot the current delivery information in the skb, to generate
- * a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered().
- */
-@@ -66,7 +84,9 @@ void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
- TCP_SKB_CB(skb)->tx.delivered_mstamp = tp->delivered_mstamp;
- TCP_SKB_CB(skb)->tx.delivered = tp->delivered;
- TCP_SKB_CB(skb)->tx.delivered_ce = tp->delivered_ce;
-+ TCP_SKB_CB(skb)->tx.lost = tp->lost;
- TCP_SKB_CB(skb)->tx.is_app_limited = tp->app_limited ? 1 : 0;
-+ tcp_set_tx_in_flight(sk, skb);
- }
-
- /* When an skb is sacked or acked, we fill in the rate sample with the (prior)
-@@ -91,18 +111,21 @@ void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
- if (!rs->prior_delivered ||
- tcp_skb_sent_after(tx_tstamp, tp->first_tx_mstamp,
- scb->end_seq, rs->last_end_seq)) {
-+ rs->prior_lost = scb->tx.lost;
- rs->prior_delivered_ce = scb->tx.delivered_ce;
- rs->prior_delivered = scb->tx.delivered;
- rs->prior_mstamp = scb->tx.delivered_mstamp;
- rs->is_app_limited = scb->tx.is_app_limited;
- rs->is_retrans = scb->sacked & TCPCB_RETRANS;
- rs->last_end_seq = scb->end_seq;
-+ rs->tx_in_flight = scb->tx.in_flight;
-
- /* Record send time of most recently ACKed packet: */
- tp->first_tx_mstamp = tx_tstamp;
- /* Find the duration of the "send phase" of this window: */
-- rs->interval_us = tcp_stamp_us_delta(tp->first_tx_mstamp,
-- scb->tx.first_tx_mstamp);
-+ rs->interval_us = tcp_stamp32_us_delta(
-+ tp->first_tx_mstamp,
-+ scb->tx.first_tx_mstamp);
-
- }
- /* Mark off the skb delivered once it's sacked to avoid being
-@@ -144,6 +167,7 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
- return;
- }
- rs->delivered = tp->delivered - rs->prior_delivered;
-+ rs->lost = tp->lost - rs->prior_lost;
-
- rs->delivered_ce = tp->delivered_ce - rs->prior_delivered_ce;
- /* delivered_ce occupies less than 32 bits in the skb control block */
-@@ -155,7 +179,7 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
- * longer phase.
- */
- snd_us = rs->interval_us; /* send phase */
-- ack_us = tcp_stamp_us_delta(tp->tcp_mstamp,
-+ ack_us = tcp_stamp32_us_delta(tp->tcp_mstamp,
- rs->prior_mstamp); /* ack phase */
- rs->interval_us = max(snd_us, ack_us);
-
-diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
-index cb79127f45c3..70e4de876a7f 100644
---- a/net/ipv4/tcp_timer.c
-+++ b/net/ipv4/tcp_timer.c
-@@ -605,6 +605,7 @@ void tcp_write_timer_handler(struct sock *sk)
- return;
- }
-
-+ tcp_rate_check_app_limited(sk);
- tcp_mstamp_refresh(tcp_sk(sk));
- event = icsk->icsk_pending;
-
---- a/net/ipv4/tcp_input.c
-+++ b/net/ipv4/tcp_input.c
-@@ -287,7 +287,7 @@
- icsk->icsk_ack.quick = quickacks;
- }
-
-+void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks)
--static void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks)
- {
- struct inet_connection_sock *icsk = inet_csk(sk);
-
-@@ -295,6 +299,7 @@
- inet_csk_exit_pingpong_mode(sk);
- icsk->icsk_ack.ato = TCP_ATO_MIN;
- }
-+EXPORT_SYMBOL(tcp_enter_quickack_mode);
-
- /* Send ACKs quickly, if "quick" count is not exhausted
- * and the session is not interactive.
---- a/include/net/tcp.h
-+++ b/include/net/tcp.h
-@@ -350,6 +350,7 @@
- struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, gfp_t gfp,
- bool force_schedule);
-
-+void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
- static inline void tcp_dec_quickack_mode(struct sock *sk)
- {
- struct inet_connection_sock *icsk = inet_csk(sk);