From d7fe3cd0dc3cff081773e8e54e0921b8027079ab Mon Sep 17 00:00:00 2001 From: Tan Zien Date: Wed, 18 Sep 2024 00:00:28 +0800 Subject: [PATCH] kernel: update TCP BBR to v3 BBR v3 is an enhacement to the BBR v1 algorithm. It's designed to aim for lower queues, lower loss, and better Reno/CUBIC coexistence than BBR v1. More information: https://github.com/google/bbr/blob/bbr-v3-upstream-prep-2024-02-19-01/README.md https://github.com/google/bbr/tree/001a430b3ddbbc6d9173061a74d8b580c757b91b Signed-off-by: Tan Zien iproute2: ss: output TCP BBRv3 diag information Add logic for printing diag information for TCP BBRv3 congestion control. Signed-off-by: Tan Zien ath79: refresh patch refresh: target/linux/ath79/patches-6.6/900-unaligned_access_hacks.patch Signed-off-by: Tan Zien --- ...ss-output-TCP-BBRv3-diag-information.patch | 165 + .../900-unaligned_access_hacks.patch | 8 +- ...den-app-limited-rate-sample-detectio.patch | 51 + ...hrink-delivered_mstamp-first_tx_msta.patch | 73 + ...napshot-packets-in-flight-at-transmi.patch | 108 + ...ount-packets-lost-over-TCP-rate-samp.patch | 69 + ...xport-FLAG_ECE-in-rate_sample.is_ece.patch | 37 + ...ntroduce-ca_ops-skb_marked_lost-CC-m.patch | 56 + ...djust-skb-tx.in_flight-upon-merge-in.patch | 58 + ...djust-skb-tx.in_flight-upon-split-in.patch | 96 + ...ca-opts-flag-TCP_CONG_WANTS_CE_EVENT.patch | 72 + ...alize-TSO-sizing-in-TCP-CC-module-AP.patch | 117 + ..._ack_mode-1-skip-rwin-check-in-tcp_f.patch | 71 + ...ecord-app-limited-status-of-TLP-repa.patch | 44 + ...nform-CC-module-of-losses-repaired-b.patch | 44 + ...ntroduce-is_acking_tlp_retrans_seq-i.patch | 72 + ...r-route-feature-RTAX_FEATURE_ECN_LOW.patch | 108 + ...pdate-TCP-bbr-congestion-control-mod.patch | 2822 +++++++++++++++++ ...nsure-ECN-enabled-BBR-flows-set-ECT-.patch | 58 + ...OPT_ECN_LOW-in-tcp_info-tcpi_options.patch | 37 + ...hange-u64-to-unsigned-long-for-bytes.patch | 36 + 21 files changed, 4198 insertions(+), 4 deletions(-) create mode 100644 package/network/utils/iproute2/patches/500-ss-output-TCP-BBRv3-diag-information.patch create mode 100644 target/linux/generic/hack-6.6/601-01-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-broaden-app-limited-rate-sample-detectio.patch create mode 100644 target/linux/generic/hack-6.6/601-02-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-shrink-delivered_mstamp-first_tx_msta.patch create mode 100644 target/linux/generic/hack-6.6/601-03-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-snapshot-packets-in-flight-at-transmi.patch create mode 100644 target/linux/generic/hack-6.6/601-04-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-count-packets-lost-over-TCP-rate-samp.patch create mode 100644 target/linux/generic/hack-6.6/601-05-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-export-FLAG_ECE-in-rate_sample.is_ece.patch create mode 100644 target/linux/generic/hack-6.6/601-06-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-ca_ops-skb_marked_lost-CC-m.patch create mode 100644 target/linux/generic/hack-6.6/601-07-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-merge-in.patch create mode 100644 target/linux/generic/hack-6.6/601-08-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-split-in.patch create mode 100644 target/linux/generic/hack-6.6/601-09-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-new-ca-opts-flag-TCP_CONG_WANTS_CE_EVENT.patch create mode 100644 target/linux/generic/hack-6.6/601-10-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-re-generalize-TSO-sizing-in-TCP-CC-module-AP.patch create mode 100644 target/linux/generic/hack-6.6/601-11-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-fast_ack_mode-1-skip-rwin-check-in-tcp_f.patch create mode 100644 target/linux/generic/hack-6.6/601-12-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-record-app-limited-status-of-TLP-repa.patch create mode 100644 target/linux/generic/hack-6.6/601-13-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-inform-CC-module-of-losses-repaired-b.patch create mode 100644 target/linux/generic/hack-6.6/601-14-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-is_acking_tlp_retrans_seq-i.patch create mode 100644 target/linux/generic/hack-6.6/601-15-bbr-v3-upstream-prep-2024-02-19-01-tcp-introduce-per-route-feature-RTAX_FEATURE_ECN_LOW.patch create mode 100644 target/linux/generic/hack-6.6/601-16-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-update-TCP-bbr-congestion-control-mod.patch create mode 100644 target/linux/generic/hack-6.6/601-17-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-ensure-ECN-enabled-BBR-flows-set-ECT-.patch create mode 100644 target/linux/generic/hack-6.6/601-18-bbr-v3-upstream-prep-2024-02-19-01-tcp-export-TCPI_OPT_ECN_LOW-in-tcp_info-tcpi_options.patch create mode 100644 target/linux/generic/hack-6.6/601-19-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-change-u64-to-unsigned-long-for-bytes.patch diff --git a/package/network/utils/iproute2/patches/500-ss-output-TCP-BBRv3-diag-information.patch b/package/network/utils/iproute2/patches/500-ss-output-TCP-BBRv3-diag-information.patch new file mode 100644 index 00000000000000..6e20dc451b4b26 --- /dev/null +++ b/package/network/utils/iproute2/patches/500-ss-output-TCP-BBRv3-diag-information.patch @@ -0,0 +1,165 @@ +From ca7f11ebc4d4a99ccfd44be8555d505b26996c12 Mon Sep 17 00:00:00 2001 +From: Arjun Roy +Date: Mon, 25 Jul 2022 12:49:35 -0400 +Subject: [PATCH 2/2] ss: output TCP BBRv3 diag information + +Add logic for printing diag information for TCP BBRv3 congestion +control. This commit leaves in place the support for printing the +earlier TCP BBRv1 congestion control information. + +Both BBRv1 and BBRv3 are using the same enum value. The BBRv3 struct +starts with the same data as BBRv1, so it is is backward-compatible +with BBRv1, to allow lder ss binaries to print basic information for +BBRv3. We use the size of the returned data and the version field to +check the version of the data. + +Signed-off-by: Arjun Roy +Signed-off-by: Neal Cardwell +Signed-off-by: David Morley +--- + include/uapi/linux/inet_diag.h | 23 ++++++++++++ + misc/ss.c | 66 +++++++++++++++++++++++++++++++++- + 2 files changed, 88 insertions(+), 1 deletion(-) + +diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h +index d81cb69a26a9..dca833ecb783 100644 +--- a/include/uapi/linux/inet_diag.h ++++ b/include/uapi/linux/inet_diag.h +@@ -229,6 +229,29 @@ struct tcp_bbr_info { + __u32 bbr_min_rtt; /* min-filtered RTT in uSec */ + __u32 bbr_pacing_gain; /* pacing gain shifted left 8 bits */ + __u32 bbr_cwnd_gain; /* cwnd gain shifted left 8 bits */ ++ __u32 bbr_bw_hi_lsb; /* lower 32 bits of bw_hi */ ++ __u32 bbr_bw_hi_msb; /* upper 32 bits of bw_hi */ ++ __u32 bbr_bw_lo_lsb; /* lower 32 bits of bw_lo */ ++ __u32 bbr_bw_lo_msb; /* upper 32 bits of bw_lo */ ++ __u8 bbr_mode; /* current bbr_mode in state machine */ ++ __u8 bbr_phase; /* current state machine phase */ ++ __u8 unused1; /* alignment padding; not used yet */ ++ __u8 bbr_version; /* BBR algorithm version */ ++ __u32 bbr_inflight_lo; /* lower short-term data volume bound */ ++ __u32 bbr_inflight_hi; /* higher long-term data volume bound */ ++ __u32 bbr_extra_acked; /* max excess packets ACKed in epoch */ ++}; ++ ++/* TCP BBR congestion control bbr_phase as reported in netlink/ss stats. */ ++enum tcp_bbr_phase { ++ BBR_PHASE_INVALID = 0, ++ BBR_PHASE_STARTUP = 1, ++ BBR_PHASE_DRAIN = 2, ++ BBR_PHASE_PROBE_RTT = 3, ++ BBR_PHASE_PROBE_BW_UP = 4, ++ BBR_PHASE_PROBE_BW_DOWN = 5, ++ BBR_PHASE_PROBE_BW_CRUISE = 6, ++ BBR_PHASE_PROBE_BW_REFILL = 7, + }; + + union tcp_cc_info { +diff --git a/misc/ss.c b/misc/ss.c +index e9d813596b91..5f413118f0dd 100644 +--- a/misc/ss.c ++++ b/misc/ss.c +@@ -912,6 +912,7 @@ struct tcpstat { + bool app_limited; + struct dctcpstat *dctcp; + struct tcp_bbr_info *bbr_info; ++ unsigned int bbr_info_len; + }; + + /* SCTP assocs share the same inode number with their parent endpoint. So if we +@@ -2585,6 +2586,29 @@ static void sctp_stats_print(struct sctp_info *s) + out(" fraginl:%d", s->sctpi_s_frag_interleave); + } + ++static const char* bbr_phase_to_str(enum tcp_bbr_phase phase) ++{ ++ switch (phase) { ++ case BBR_PHASE_STARTUP: ++ return "STARTUP"; ++ case BBR_PHASE_DRAIN: ++ return "DRAIN"; ++ case BBR_PHASE_PROBE_RTT: ++ return "PROBE_RTT"; ++ case BBR_PHASE_PROBE_BW_UP: ++ return "PROBE_BW_UP"; ++ case BBR_PHASE_PROBE_BW_DOWN: ++ return "PROBE_BW_DOWN"; ++ case BBR_PHASE_PROBE_BW_CRUISE: ++ return "PROBE_BW_CRUISE"; ++ case BBR_PHASE_PROBE_BW_REFILL: ++ return "PROBE_BW_REFILL"; ++ case BBR_PHASE_INVALID: ++ default: ++ return "INVALID"; ++ } ++} ++ + static void tcp_stats_print(struct tcpstat *s) + { + char b1[64]; +@@ -2658,7 +2682,14 @@ static void tcp_stats_print(struct tcpstat *s) + } + + if (s->bbr_info) { +- __u64 bw; ++ /* All versions of the BBR algorithm use the INET_DIAG_BBRINFO ++ * enum value. Later versions of the tcp_bbr_info struct are ++ * backward-compatible with earlier versions, to allow older ss ++ * binaries to print basic information for newer versions of ++ * the algorithm. We use the size of the returned tcp_bbr_info ++ * struct to decide how much to print. ++ */ ++ __u64 bw, bw_hi, bw_lo; + + bw = s->bbr_info->bbr_bw_hi; + bw <<= 32; +@@ -2673,6 +2704,38 @@ static void tcp_stats_print(struct tcpstat *s) + if (s->bbr_info->bbr_cwnd_gain) + out(",cwnd_gain:%g", + (double)s->bbr_info->bbr_cwnd_gain / 256.0); ++ ++ if (s->bbr_info_len >= ++ (offsetof(struct tcp_bbr_info, bbr_extra_acked) + ++ sizeof(__u32))) { ++ ++ bw_hi = s->bbr_info->bbr_bw_hi_msb; ++ bw_hi <<= 32; ++ bw_hi |= s->bbr_info->bbr_bw_hi_lsb; ++ ++ bw_lo = s->bbr_info->bbr_bw_lo_msb; ++ bw_lo <<= 32; ++ bw_lo |= s->bbr_info->bbr_bw_lo_lsb; ++ ++ out(",version:%u", s->bbr_info->bbr_version); ++ if (bw_hi != ~0UL) ++ out(",bw_hi:%sbps", sprint_bw(b1, bw_hi * 8.0)); ++ if (bw_lo != ~0UL) ++ out(",bw_lo:%sbps", sprint_bw(b1, bw_lo * 8.0)); ++ if (s->bbr_info->bbr_inflight_hi != ~0U) ++ out(",inflight_hi:%u", ++ s->bbr_info->bbr_inflight_hi); ++ if (s->bbr_info->bbr_inflight_lo != ~0U) ++ out(",inflight_lo:%u", ++ s->bbr_info->bbr_inflight_lo); ++ out(",extra_acked:%u", s->bbr_info->bbr_extra_acked); ++ out(",mode:%d", (int)s->bbr_info->bbr_mode); ++ out(",phase:%s", ++ bbr_phase_to_str( ++ (enum tcp_bbr_phase) ++ s->bbr_info->bbr_phase)); ++ } ++ + out(")"); + } + +@@ -3147,6 +3210,7 @@ static void tcp_show_info(const struct nlmsghdr *nlh, struct inet_diag_msg *r, + s.bbr_info = calloc(1, sizeof(*s.bbr_info)); + if (s.bbr_info && bbr_info) + memcpy(s.bbr_info, bbr_info, len); ++ s.bbr_info_len = len; + } + + if (rtt > 0 && info->tcpi_snd_mss && info->tcpi_snd_cwnd) { +-- +2.41.0.487.g6d72f3e995-goog + diff --git a/target/linux/ath79/patches-6.6/900-unaligned_access_hacks.patch b/target/linux/ath79/patches-6.6/900-unaligned_access_hacks.patch index 969cde5ce27901..27943b87422e5f 100644 --- a/target/linux/ath79/patches-6.6/900-unaligned_access_hacks.patch +++ b/target/linux/ath79/patches-6.6/900-unaligned_access_hacks.patch @@ -350,7 +350,7 @@ SVN-Revision: 35130 list_for_each_entry(p, head, list) { --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c -@@ -622,48 +622,53 @@ static void tcp_options_write(struct tcp +@@ -625,48 +625,53 @@ static void tcp_options_write(struct tcp u16 options = opts->options; /* mungable copy */ if (unlikely(OPTION_MD5 & options)) { @@ -427,7 +427,7 @@ SVN-Revision: 35130 } if (unlikely(opts->num_sack_blocks)) { -@@ -671,16 +676,17 @@ static void tcp_options_write(struct tcp +@@ -674,16 +679,17 @@ static void tcp_options_write(struct tcp tp->duplicate_sack : tp->selective_acks; int this_sack; @@ -451,7 +451,7 @@ SVN-Revision: 35130 } tp->rx_opt.dsack = 0; -@@ -693,13 +699,14 @@ static void tcp_options_write(struct tcp +@@ -696,13 +702,14 @@ static void tcp_options_write(struct tcp if (foc->exp) { len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; @@ -751,7 +751,7 @@ SVN-Revision: 35130 EXPORT_SYMBOL(xfrm_parse_spi); --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c -@@ -4262,14 +4262,16 @@ static bool tcp_parse_aligned_timestamp( +@@ -4287,14 +4287,16 @@ static bool tcp_parse_aligned_timestamp( { const __be32 *ptr = (const __be32 *)(th + 1); diff --git a/target/linux/generic/hack-6.6/601-01-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-broaden-app-limited-rate-sample-detectio.patch b/target/linux/generic/hack-6.6/601-01-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-broaden-app-limited-rate-sample-detectio.patch new file mode 100644 index 00000000000000..37b43a9c036891 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-01-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-broaden-app-limited-rate-sample-detectio.patch @@ -0,0 +1,51 @@ +From 304c6ff637e53c8f3530a0bb50ba95e532d681b8 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Tue, 11 Jun 2019 12:26:55 -0400 +Subject: [PATCH 01/19] net-tcp_bbr: broaden app-limited rate sample detection + +This commit is a bug fix for the Linux TCP app-limited +(application-limited) logic that is used for collecting rate +(bandwidth) samples. + +Previously the app-limited logic only looked for "bubbles" of +silence in between application writes, by checking at the start +of each sendmsg. But "bubbles" of silence can also happen before +retransmits: e.g. bubbles can happen between an application write +and a retransmit, or between two retransmits. + +Retransmits are triggered by ACKs or timers. So this commit checks +for bubbles of app-limited silence upon ACKs or timers. + +Why does this commit check for app-limited state at the start of +ACKs and timer handling? Because at that point we know whether +inflight was fully using the cwnd. During processing the ACK or +timer event we often change the cwnd; after changing the cwnd we +can't know whether inflight was fully using the old cwnd. + +Origin-9xx-SHA1: 3fe9b53291e018407780fb8c356adb5666722cbc +Change-Id: I37221506f5166877c2b110753d39bb0757985e68 +--- + net/ipv4/tcp_input.c | 1 + + net/ipv4/tcp_timer.c | 1 + + 2 files changed, 2 insertions(+) + +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -3915,6 +3915,7 @@ static int tcp_ack(struct sock *sk, cons + + 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. +--- a/net/ipv4/tcp_timer.c ++++ b/net/ipv4/tcp_timer.c +@@ -677,6 +677,7 @@ void tcp_write_timer_handler(struct sock + return; + } + ++ tcp_rate_check_app_limited(sk); + tcp_mstamp_refresh(tcp_sk(sk)); + event = icsk->icsk_pending; + diff --git a/target/linux/generic/hack-6.6/601-02-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-shrink-delivered_mstamp-first_tx_msta.patch b/target/linux/generic/hack-6.6/601-02-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-shrink-delivered_mstamp-first_tx_msta.patch new file mode 100644 index 00000000000000..ee7195893eeaab --- /dev/null +++ b/target/linux/generic/hack-6.6/601-02-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-shrink-delivered_mstamp-first_tx_msta.patch @@ -0,0 +1,73 @@ +From 5a47eb49ad406b439a00b90f5285359cd1e876f4 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Sun, 24 Jun 2018 21:55:59 -0400 +Subject: [PATCH 02/19] net-tcp_bbr: v2: shrink delivered_mstamp, + first_tx_mstamp to u32 to free up 8 bytes + +Free up some space for tracking inflight and losses for each +bw sample, in upcoming commits. + +These timestamps are in microseconds, and are now stored in 32 +bits. So they can only hold time intervals up to roughly 2^12 = 4096 +seconds. But Linux TCP RTT and RTO tracking has the same 32-bit +microsecond implementation approach and resulting deployment +limitations. So this is not introducing a new limit. And these should +not be a limitation for the foreseeable future. + +Effort: net-tcp_bbr +Origin-9xx-SHA1: 238a7e6b5d51625fef1ce7769826a7b21b02ae55 +Change-Id: I3b779603797263b52a61ad57c565eb91fe42680c +--- + include/net/tcp.h | 9 +++++++-- + net/ipv4/tcp_rate.c | 7 ++++--- + 2 files changed, 11 insertions(+), 5 deletions(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -822,6 +822,11 @@ static inline u32 tcp_stamp_us_delta(u64 + 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); +@@ -897,9 +902,9 @@ 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; + } tx; /* only used for outgoing skbs */ + union { + struct inet_skb_parm h4; +--- a/net/ipv4/tcp_rate.c ++++ b/net/ipv4/tcp_rate.c +@@ -101,8 +101,9 @@ void tcp_rate_skb_delivered(struct sock + /* 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 +@@ -155,7 +156,7 @@ void tcp_rate_gen(struct sock *sk, u32 d + * 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/target/linux/generic/hack-6.6/601-03-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-snapshot-packets-in-flight-at-transmi.patch b/target/linux/generic/hack-6.6/601-03-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-snapshot-packets-in-flight-at-transmi.patch new file mode 100644 index 00000000000000..f0e4e9b392ebeb --- /dev/null +++ b/target/linux/generic/hack-6.6/601-03-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-snapshot-packets-in-flight-at-transmi.patch @@ -0,0 +1,108 @@ +From de4ff1045b5dec6998549c1a1d7d5eae3500360a Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Sat, 5 Aug 2017 11:49:50 -0400 +Subject: [PATCH 03/19] net-tcp_bbr: v2: snapshot packets in flight at transmit + time and pass in rate_sample + +CC algorithms may want to snapshot the number of packets in flight at +transmit time and pass in rate_sample, to understand the relationship +between inflight and losses or ECN signals, to try to find the highest +inflight value that has acceptable levels of loss/ECN marking. + +We split out the code to set an skb's tx.in_flight field into its own +function, so that this code can be used for the TCP_REPAIR "fake send" +code path that inserts skbs into the rtx queue without sending them. + +Effort: net-tcp_bbr +Origin-9xx-SHA1: b3eb4f2d20efab4ca001f32c9294739036c493ea +Origin-9xx-SHA1: e880fc907d06ea7354333f60f712748ebce9497b +Origin-9xx-SHA1: 330f825a08a6fe92cef74d799cc468864c479f63 +Change-Id: I7314047d0ff14dd261a04b1969a46dc658c8836a +--- + include/net/tcp.h | 6 ++++++ + net/ipv4/tcp_output.c | 1 + + net/ipv4/tcp_rate.c | 20 ++++++++++++++++++++ + 3 files changed, 27 insertions(+) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -905,6 +905,10 @@ struct tcp_skb_cb { + u32 first_tx_mstamp; + /* when we reached the "delivered" count */ + 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; + } tx; /* only used for outgoing skbs */ + union { + struct inet_skb_parm h4; +@@ -1052,6 +1056,7 @@ struct rate_sample { + u64 prior_mstamp; /* starting timestamp for interval */ + 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 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" */ +@@ -1174,6 +1179,7 @@ static inline void tcp_ca_event(struct s + 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); +--- a/net/ipv4/tcp_output.c ++++ b/net/ipv4/tcp_output.c +@@ -2701,6 +2701,7 @@ static bool tcp_write_xmit(struct sock * + 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 */ + } + +--- 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(). + */ +@@ -67,6 +85,7 @@ void tcp_rate_skb_sent(struct sock *sk, + TCP_SKB_CB(skb)->tx.delivered = tp->delivered; + TCP_SKB_CB(skb)->tx.delivered_ce = tp->delivered_ce; + 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) +@@ -96,6 +115,7 @@ void tcp_rate_skb_delivered(struct sock + rs->prior_mstamp = scb->tx.delivered_mstamp; + rs->is_app_limited = scb->tx.is_app_limited; + rs->is_retrans = scb->sacked & TCPCB_RETRANS; ++ rs->tx_in_flight = scb->tx.in_flight; + rs->last_end_seq = scb->end_seq; + + /* Record send time of most recently ACKed packet: */ diff --git a/target/linux/generic/hack-6.6/601-04-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-count-packets-lost-over-TCP-rate-samp.patch b/target/linux/generic/hack-6.6/601-04-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-count-packets-lost-over-TCP-rate-samp.patch new file mode 100644 index 00000000000000..39c037e6544b78 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-04-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-count-packets-lost-over-TCP-rate-samp.patch @@ -0,0 +1,69 @@ +From f370a83a7972e08799316b0de5fb67b63b14c5e4 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Thu, 12 Oct 2017 23:44:27 -0400 +Subject: [PATCH 04/19] net-tcp_bbr: v2: count packets lost over TCP rate + sampling interval + +For understanding the relationship between inflight and packet loss +signals, to try to find the highest inflight value that has acceptable +levels of packet losses. + +Effort: net-tcp_bbr +Origin-9xx-SHA1: 4527e26b2bd7756a88b5b9ef1ada3da33dd609ab +Change-Id: I594c2500868d9c530770e7ddd68ffc87c57f4fd5 +--- + include/net/tcp.h | 5 ++++- + net/ipv4/tcp_rate.c | 3 +++ + 2 files changed, 7 insertions(+), 1 deletion(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -909,6 +909,7 @@ struct tcp_skb_cb { + #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; +@@ -1054,11 +1055,13 @@ 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*/ ++ s32 delivered_ce; /* packets delivered w/ CE mark over interval */ + long interval_us; /* time for tp->delivered to incr "delivered" */ + u32 snd_interval_us; /* snd interval for delivered packets */ + u32 rcv_interval_us; /* rcv interval for delivered packets */ +--- a/net/ipv4/tcp_rate.c ++++ b/net/ipv4/tcp_rate.c +@@ -84,6 +84,7 @@ void tcp_rate_skb_sent(struct sock *sk, + 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); + } +@@ -110,6 +111,7 @@ void tcp_rate_skb_delivered(struct sock + 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; +@@ -165,6 +167,7 @@ void tcp_rate_gen(struct sock *sk, u32 d + 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 */ diff --git a/target/linux/generic/hack-6.6/601-05-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-export-FLAG_ECE-in-rate_sample.is_ece.patch b/target/linux/generic/hack-6.6/601-05-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-export-FLAG_ECE-in-rate_sample.is_ece.patch new file mode 100644 index 00000000000000..066f276d93fd64 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-05-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-export-FLAG_ECE-in-rate_sample.is_ece.patch @@ -0,0 +1,37 @@ +From 39cad6f5ef38be886ef73766b8e01ab80a2ee6c6 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Mon, 19 Nov 2018 13:48:36 -0500 +Subject: [PATCH 05/19] net-tcp_bbr: v2: export FLAG_ECE in rate_sample.is_ece + +For understanding the relationship between inflight and ECN signals, +to try to find the highest inflight value that has acceptable levels +ECN marking. + +Effort: net-tcp_bbr +Origin-9xx-SHA1: 3eba998f2898541406c2666781182200934965a8 +Change-Id: I3a964e04cee83e11649a54507043d2dfe769a3b3 +--- + include/net/tcp.h | 1 + + net/ipv4/tcp_input.c | 1 + + 2 files changed, 2 insertions(+) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1073,6 +1073,7 @@ 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 { +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -4014,6 +4014,7 @@ static int tcp_ack(struct sock *sk, cons + 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); diff --git a/target/linux/generic/hack-6.6/601-06-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-ca_ops-skb_marked_lost-CC-m.patch b/target/linux/generic/hack-6.6/601-06-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-ca_ops-skb_marked_lost-CC-m.patch new file mode 100644 index 00000000000000..c1c3a706a01500 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-06-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-ca_ops-skb_marked_lost-CC-m.patch @@ -0,0 +1,56 @@ +From 0dfc73a322b79b9bcc49ff662055051e2016e8d5 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Tue, 7 Aug 2018 21:52:06 -0400 +Subject: [PATCH 06/19] net-tcp_bbr: v2: introduce ca_ops->skb_marked_lost() CC + module callback API + +For connections experiencing reordering, RACK can mark packets lost +long after we receive the SACKs/ACKs hinting that the packets were +actually lost. + +This means that CC modules cannot easily learn the volume of inflight +data at which packet loss happens by looking at the current inflight +or even the packets in flight when the most recently SACKed packet was +sent. To learn this, CC modules need to know how many packets were in +flight at the time lost packets were sent. This new callback, combined +with TCP_SKB_CB(skb)->tx.in_flight, allows them to learn this. + +This also provides a consistent callback that is invoked whether +packets are marked lost upon ACK processing, using the RACK reordering +timer, or at RTO time. + +Effort: net-tcp_bbr +Origin-9xx-SHA1: afcbebe3374e4632ac6714d39e4dc8a8455956f4 +Change-Id: I54826ab53df636be537e5d3c618a46145d12d51a +--- + include/net/tcp.h | 3 +++ + net/ipv4/tcp_input.c | 5 +++++ + 2 files changed, 8 insertions(+) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1100,6 +1100,9 @@ struct tcp_congestion_ops { + /* override sysctl_tcp_min_tso_segs */ + u32 (*min_tso_segs)(struct sock *sk); + ++ /* 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) + */ +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -1103,7 +1103,12 @@ static void tcp_verify_retransmit_hint(s + */ + 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) diff --git a/target/linux/generic/hack-6.6/601-07-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-merge-in.patch b/target/linux/generic/hack-6.6/601-07-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-merge-in.patch new file mode 100644 index 00000000000000..086a6e6d07aad2 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-07-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-merge-in.patch @@ -0,0 +1,58 @@ +From 558995126fb090c0428904cde7fa70fdd30027be Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Wed, 1 May 2019 20:16:33 -0400 +Subject: [PATCH 07/19] net-tcp_bbr: v2: adjust skb tx.in_flight upon merge in + tcp_shifted_skb() + +When tcp_shifted_skb() updates state as adjacent SACKed skbs are +coalesced, previously the tx.in_flight was not adjusted, so we could +get contradictory state where the skb's recorded pcount was bigger +than the tx.in_flight (the number of segments that were in_flight +after sending the skb). + +Normally have a SACKed skb with contradictory pcount/tx.in_flight +would not matter. However, with SACK reneging, the SACKed bit is +removed, and an skb once again becomes eligible for retransmitting, +fragmenting, SACKing, etc. Packetdrill testing verified the following +sequence is possible in a kernel that does not have this commit: + + - skb N is SACKed + - skb N+1 is SACKed and combined with skb N using tcp_shifted_skb() + - tcp_shifted_skb() will increase the pcount of prev, + but leave tx.in_flight as-is + - so prev skb can have pcount > tx.in_flight + - RTO, tcp_timeout_mark_lost(), detect reneg, + remove "SACKed" bit, mark skb N as lost + - find pcount of skb N is greater than its tx.in_flight + +I suspect this issue iw what caused the bbr2_inflight_hi_from_lost_skb(): + WARN_ON_ONCE(inflight_prev < 0) +to fire in production machines using bbr2. + +Effort: net-tcp_bbr +Origin-9xx-SHA1: 1a3e997e613d2dcf32b947992882854ebe873715 +Change-Id: I1b0b75c27519953430c7db51c6f358f104c7af55 +--- + net/ipv4/tcp_input.c | 11 +++++++++++ + 1 file changed, 11 insertions(+) + +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -1489,6 +1489,17 @@ static bool tcp_shifted_skb(struct sock + 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 diff --git a/target/linux/generic/hack-6.6/601-08-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-split-in.patch b/target/linux/generic/hack-6.6/601-08-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-split-in.patch new file mode 100644 index 00000000000000..db05aa94cedf75 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-08-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-adjust-skb-tx.in_flight-upon-split-in.patch @@ -0,0 +1,96 @@ +From cc06e420c17a12db64fd8c460d00cc60d5f5106f Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Wed, 1 May 2019 20:16:25 -0400 +Subject: [PATCH 08/19] net-tcp_bbr: v2: adjust skb tx.in_flight upon split in + tcp_fragment() + +When we fragment an skb that has already been sent, we need to update +the tx.in_flight for the first skb in the resulting pair ("buff"). + +Because we were not updating the tx.in_flight, the tx.in_flight value +was inconsistent with the pcount of the "buff" skb (tx.in_flight would +be too high). That meant that if the "buff" skb was lost, then +bbr2_inflight_hi_from_lost_skb() would calculate an inflight_hi value +that is too high. This could result in longer queues and higher packet +loss. + +Packetdrill testing verified that without this commit, when the second +half of an skb is SACKed and then later the first half of that skb is +marked lost, the calculated inflight_hi was incorrect. + +Effort: net-tcp_bbr +Origin-9xx-SHA1: 385f1ddc610798fab2837f9f372857438b25f874 +Origin-9xx-SHA1: a0eb099690af net-tcp_bbr: v2: fix tcp_fragment() tx.in_flight recomputation [prod feb 8 2021; use as a fixup] +Origin-9xx-SHA1: 885503228153ff0c9114e net-tcp_bbr: v2: introduce tcp_skb_tx_in_flight_is_suspicious() helper for warnings +Change-Id: I617f8cab4e9be7a0b8e8d30b047bf8645393354d +--- + include/net/tcp.h | 15 +++++++++++++++ + net/ipv4/tcp_output.c | 26 +++++++++++++++++++++++++- + 2 files changed, 40 insertions(+), 1 deletion(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1199,6 +1199,21 @@ static inline bool tcp_skb_sent_after(u6 + return t1 > t2 || (t1 == t2 && after(seq1, seq2)); + } + ++/* If a retransmit failed due to local qdisc congestion or other local issues, ++ * then we may have called tcp_set_skb_tso_segs() to increase the number of ++ * segments in the skb without increasing the tx.in_flight. In all other cases, ++ * the tx.in_flight should be at least as big as the pcount of the sk_buff. We ++ * do not have the state to know whether a retransmit failed due to local qdisc ++ * congestion or other local issues, so to avoid spurious warnings we consider ++ * that any skb marked lost may have suffered that fate. ++ */ ++static inline bool tcp_skb_tx_in_flight_is_suspicious(u32 skb_pcount, ++ u32 skb_sacked_flags, ++ u32 tx_in_flight) ++{ ++ return (skb_pcount > tx_in_flight) && !(skb_sacked_flags & TCPCB_LOST); ++} ++ + /* These functions determine how the current flow behaves in respect of SACK + * handling. SACK is negotiated with the peer, and therefore it can vary + * between different flows. +--- a/net/ipv4/tcp_output.c ++++ b/net/ipv4/tcp_output.c +@@ -1548,7 +1548,7 @@ int tcp_fragment(struct sock *sk, enum t + { + 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; +@@ -1623,6 +1623,30 @@ int tcp_fragment(struct sock *sk, enum t + + if (diff) + tcp_adjust_pcount(sk, skb, diff); ++ ++ inflight_prev = TCP_SKB_CB(skb)->tx.in_flight - old_factor; ++ if (inflight_prev < 0) { ++ WARN_ONCE(tcp_skb_tx_in_flight_is_suspicious( ++ old_factor, ++ TCP_SKB_CB(skb)->sacked, ++ TCP_SKB_CB(skb)->tx.in_flight), ++ "inconsistent: tx.in_flight: %u " ++ "old_factor: %d mss: %u sacked: %u " ++ "1st pcount: %d 2nd pcount: %d " ++ "1st len: %u 2nd len: %u ", ++ TCP_SKB_CB(skb)->tx.in_flight, old_factor, ++ mss_now, TCP_SKB_CB(skb)->sacked, ++ tcp_skb_pcount(skb), tcp_skb_pcount(buff), ++ skb->len, buff->len); ++ inflight_prev = 0; ++ } ++ /* Set 1st tx.in_flight as if 1st were sent by itself: */ ++ TCP_SKB_CB(skb)->tx.in_flight = inflight_prev + ++ tcp_skb_pcount(skb); ++ /* Set 2nd tx.in_flight with new 1st and 2nd pcounts: */ ++ TCP_SKB_CB(buff)->tx.in_flight = inflight_prev + ++ tcp_skb_pcount(skb) + ++ tcp_skb_pcount(buff); + } + + /* Link BUFF into the send queue. */ diff --git a/target/linux/generic/hack-6.6/601-09-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-new-ca-opts-flag-TCP_CONG_WANTS_CE_EVENT.patch b/target/linux/generic/hack-6.6/601-09-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-new-ca-opts-flag-TCP_CONG_WANTS_CE_EVENT.patch new file mode 100644 index 00000000000000..97b7b6d4f4d960 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-09-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-new-ca-opts-flag-TCP_CONG_WANTS_CE_EVENT.patch @@ -0,0 +1,72 @@ +From f9303263a3dedd48b477b226e15ebe171ff5ed09 Mon Sep 17 00:00:00 2001 +From: Yousuk Seung +Date: Wed, 23 May 2018 17:55:54 -0700 +Subject: [PATCH 09/19] net-tcp: add new ca opts flag TCP_CONG_WANTS_CE_EVENTS + +Add a a new ca opts flag TCP_CONG_WANTS_CE_EVENTS that allows a +congestion control module to receive CE events. + +Currently congestion control modules have to set the TCP_CONG_NEEDS_ECN +bit in opts flag to receive CE events but this may incur changes in ECN +behavior elsewhere. This patch adds a new bit TCP_CONG_WANTS_CE_EVENTS +that allows congestion control modules to receive CE events +independently of TCP_CONG_NEEDS_ECN. + +Effort: net-tcp +Origin-9xx-SHA1: 9f7e14716cde760bc6c67ef8ef7e1ee48501d95b +Change-Id: I2255506985242f376d910c6fd37daabaf4744f24 +--- + include/net/tcp.h | 14 +++++++++++++- + net/ipv4/tcp_input.c | 4 ++-- + 2 files changed, 15 insertions(+), 3 deletions(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1035,7 +1035,11 @@ 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; + +@@ -1167,6 +1171,14 @@ static inline char *tcp_ca_get_name_by_k + } + #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); +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -376,7 +376,7 @@ static void __tcp_ecn_check_ce(struct so + 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)) { +@@ -387,7 +387,7 @@ static void __tcp_ecn_check_ce(struct so + 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; diff --git a/target/linux/generic/hack-6.6/601-10-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-re-generalize-TSO-sizing-in-TCP-CC-module-AP.patch b/target/linux/generic/hack-6.6/601-10-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-re-generalize-TSO-sizing-in-TCP-CC-module-AP.patch new file mode 100644 index 00000000000000..3675602dcd5ea5 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-10-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-re-generalize-TSO-sizing-in-TCP-CC-module-AP.patch @@ -0,0 +1,117 @@ +From eb5151a8c0aba2b3cffc6fe370c7594f9bf39164 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Fri, 27 Sep 2019 17:10:26 -0400 +Subject: [PATCH 10/19] net-tcp: re-generalize TSO sizing in TCP CC module API + +Reorganize the API for CC modules so that the CC module once again +gets complete control of the TSO sizing decision. This is how the API +was set up around 2016 and the initial BBRv1 upstreaming. Later Eric +Dumazet simplified it. But with wider testing it now seems that to +avoid CPU regressions BBR needs to have a different TSO sizing +function. + +This is necessary to handle cases where there are many flows +bottlenecked on the sender host's NIC, in which case BBR's pacing rate +is much lower than CUBIC/Reno/DCTCP's. Why does this happen? Because +BBR's pacing rate adapts to the low bandwidth share each flow sees. By +contrast, CUBIC/Reno/DCTCP see no loss or ECN, so they grow a very +large cwnd, and thus large pacing rate and large TSO burst size. + +Change-Id: Ic8ccfdbe4010ee8d4bf6a6334c48a2fceb2171ea +--- + include/net/tcp.h | 4 ++-- + net/ipv4/tcp_bbr.c | 37 ++++++++++++++++++++++++++----------- + net/ipv4/tcp_output.c | 11 +++++------ + 3 files changed, 33 insertions(+), 19 deletions(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1101,8 +1101,8 @@ 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); +--- a/net/ipv4/tcp_bbr.c ++++ b/net/ipv4/tcp_bbr.c +@@ -300,20 +300,35 @@ __bpf_kfunc static u32 bbr_min_tso_segs( + 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, 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_MAX_SIZE); + } + + /* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */ +@@ -1149,7 +1164,7 @@ static struct tcp_congestion_ops tcp_bbr + .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, + }; +--- a/net/ipv4/tcp_output.c ++++ b/net/ipv4/tcp_output.c +@@ -2022,13 +2022,12 @@ static u32 tcp_tso_autosize(const struct + 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; ++ u32 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); +- +- 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, ++ sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); + return min_t(u32, tso_segs, sk->sk_gso_max_segs); + } + diff --git a/target/linux/generic/hack-6.6/601-11-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-fast_ack_mode-1-skip-rwin-check-in-tcp_f.patch b/target/linux/generic/hack-6.6/601-11-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-fast_ack_mode-1-skip-rwin-check-in-tcp_f.patch new file mode 100644 index 00000000000000..9f98ca87a03acf --- /dev/null +++ b/target/linux/generic/hack-6.6/601-11-bbr-v3-upstream-prep-2024-02-19-01-net-tcp-add-fast_ack_mode-1-skip-rwin-check-in-tcp_f.patch @@ -0,0 +1,71 @@ +From 9a61c63fcbda3770a3d582069b3f20d5d02000fa Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Sat, 16 Nov 2019 13:16:25 -0500 +Subject: [PATCH 11/19] net-tcp: add fast_ack_mode=1: skip rwin check in + tcp_fast_ack_mode__tcp_ack_snd_check() + +Add logic for an experimental TCP connection behavior, enabled with +tp->fast_ack_mode = 1, which disables checking the receive window +before sending an ack in __tcp_ack_snd_check(). If this behavior is +enabled, the data receiver sends an ACK if the amount of data is > +RCV.MSS. + +Change-Id: Iaa0a0fd7108221f883137a79d5bfa724f1b096d4 +--- + include/linux/tcp.h | 3 ++- + net/ipv4/tcp.c | 1 + + net/ipv4/tcp_cong.c | 1 + + net/ipv4/tcp_input.c | 5 +++-- + 4 files changed, 7 insertions(+), 3 deletions(-) + +--- a/include/linux/tcp.h ++++ b/include/linux/tcp.h +@@ -257,7 +257,8 @@ 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 */ +--- a/net/ipv4/tcp.c ++++ b/net/ipv4/tcp.c +@@ -3099,6 +3099,7 @@ int tcp_disconnect(struct sock *sk, int + 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 */ +--- a/net/ipv4/tcp_cong.c ++++ b/net/ipv4/tcp_cong.c +@@ -240,6 +240,7 @@ void tcp_init_congestion_control(struct + 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)) +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -5662,13 +5662,14 @@ static void __tcp_ack_snd_check(struct s + + /* 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/target/linux/generic/hack-6.6/601-12-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-record-app-limited-status-of-TLP-repa.patch b/target/linux/generic/hack-6.6/601-12-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-record-app-limited-status-of-TLP-repa.patch new file mode 100644 index 00000000000000..16550efca59cf7 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-12-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-record-app-limited-status-of-TLP-repa.patch @@ -0,0 +1,44 @@ +From cec5a43a23d36dd7cfcaddb9aa40a90989017331 Mon Sep 17 00:00:00 2001 +From: Jianfeng Wang +Date: Fri, 19 Jun 2020 17:33:45 +0000 +Subject: [PATCH 12/19] net-tcp_bbr: v2: record app-limited status of + TLP-repaired flight + +When sending a TLP retransmit, record whether the outstanding flight +of data is application limited. This is important for congestion +control modules that want to respond to losses repaired by TLP +retransmits. This is important because the following scenarios convey +very different information: + (1) a packet loss with a small number of packets in flight; + (2) a packet loss with the maximum amount of data in flight allowed + by the CC module; + +Effort: net-tcp_bbr +Change-Id: Ic8ae567caa4e4bfd5fd82c3d4be12a5d9171655e +--- + include/linux/tcp.h | 3 ++- + net/ipv4/tcp_output.c | 1 + + 2 files changed, 3 insertions(+), 1 deletion(-) + +--- a/include/linux/tcp.h ++++ b/include/linux/tcp.h +@@ -258,7 +258,8 @@ struct tcp_sock { + u8 dup_ack_counter:2, + tlp_retrans:1, /* TLP is a retransmission */ + fast_ack_mode:2, /* which fast ack mode ? */ +- unused:3; ++ tlp_orig_data_app_limited:1, /* app-limited before TLP rtx? */ ++ unused:2; + 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 */ +--- a/net/ipv4/tcp_output.c ++++ b/net/ipv4/tcp_output.c +@@ -2938,6 +2938,7 @@ void tcp_send_loss_probe(struct sock *sk + if (WARN_ON(!skb || !tcp_skb_pcount(skb))) + goto rearm_timer; + ++ tp->tlp_orig_data_app_limited = TCP_SKB_CB(skb)->tx.is_app_limited; + if (__tcp_retransmit_skb(sk, skb, 1)) + goto rearm_timer; + diff --git a/target/linux/generic/hack-6.6/601-13-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-inform-CC-module-of-losses-repaired-b.patch b/target/linux/generic/hack-6.6/601-13-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-inform-CC-module-of-losses-repaired-b.patch new file mode 100644 index 00000000000000..cca0cb6d11341f --- /dev/null +++ b/target/linux/generic/hack-6.6/601-13-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-inform-CC-module-of-losses-repaired-b.patch @@ -0,0 +1,44 @@ +From 087d67017b72863366d5352616bb2a363e970117 Mon Sep 17 00:00:00 2001 +From: Jianfeng Wang +Date: Tue, 16 Jun 2020 17:41:19 +0000 +Subject: [PATCH 13/19] net-tcp_bbr: v2: inform CC module of losses repaired by + TLP probe + +Before this commit, when there is a packet loss that creates a sequence +hole that is filled by a TLP loss probe, then tcp_process_tlp_ack() +only informs the congestion control (CC) module via a back-to-back entry +and exit of CWR. But some congestion control modules (e.g. BBR) do not +respond to CWR events. + +This commit adds a new CA event with which the core TCP stack notifies +the CC module when a loss is repaired by a TLP. This will allow CC +modules that do not use the CWR mechanism to have a custom handler for +such TLP recoveries. + +Effort: net-tcp_bbr +Change-Id: Ieba72332b401b329bff5a641d2b2043a3fb8f632 +--- + include/net/tcp.h | 1 + + net/ipv4/tcp_input.c | 1 + + 2 files changed, 2 insertions(+) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1013,6 +1013,7 @@ enum tcp_ca_event { + CA_EVENT_LOSS, /* loss timeout */ + CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ + CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ ++ CA_EVENT_TLP_RECOVERY, /* a lost segment was repaired by TLP probe */ + }; + + /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -3813,6 +3813,7 @@ static void tcp_process_tlp_ack(struct s + /* ACK advances: there was a loss, so reduce cwnd. Reset + * tlp_high_seq in tcp_init_cwnd_reduction() + */ ++ tcp_ca_event(sk, CA_EVENT_TLP_RECOVERY); + tcp_init_cwnd_reduction(sk); + tcp_set_ca_state(sk, TCP_CA_CWR); + tcp_end_cwnd_reduction(sk); diff --git a/target/linux/generic/hack-6.6/601-14-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-is_acking_tlp_retrans_seq-i.patch b/target/linux/generic/hack-6.6/601-14-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-is_acking_tlp_retrans_seq-i.patch new file mode 100644 index 00000000000000..66375196cdee6a --- /dev/null +++ b/target/linux/generic/hack-6.6/601-14-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v2-introduce-is_acking_tlp_retrans_seq-i.patch @@ -0,0 +1,72 @@ +From 0388564bd3250ae87983d2b40440f4b5fdee7853 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Mon, 21 Sep 2020 14:46:26 -0400 +Subject: [PATCH 14/19] net-tcp_bbr: v2: introduce is_acking_tlp_retrans_seq + into rate_sample + +Introduce is_acking_tlp_retrans_seq into rate_sample. This bool will +export to the CC module the knowledge of whether the current ACK +matched a TLP retransmit. + +Note that when this bool is true, we cannot yet tell (in general) whether +this ACK is for the original or the TLP retransmit. + +Effort: net-tcp_bbr +Change-Id: I2e6494332167e75efcbdc99bd5c119034e9c39b4 +--- + include/net/tcp.h | 1 + + net/ipv4/tcp_input.c | 12 +++++++++--- + 2 files changed, 10 insertions(+), 3 deletions(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1077,6 +1077,7 @@ struct rate_sample { + u32 last_end_seq; /* end_seq of most recently ACKed packet */ + bool is_app_limited; /* is sample from packet with bubble in pipe? */ + bool is_retrans; /* is sample from retransmission? */ ++ bool is_acking_tlp_retrans_seq; /* ACKed a TLP retransmit sequence? */ + bool is_ack_delayed; /* is this (likely) a delayed ACK? */ + bool is_ece; /* did this ACK have ECN marked? */ + }; +--- a/net/ipv4/tcp_input.c ++++ b/net/ipv4/tcp_input.c +@@ -3796,7 +3796,8 @@ static void tcp_replace_ts_recent(struct + /* This routine deals with acks during a TLP episode and ends an episode by + * resetting tlp_high_seq. Ref: TLP algorithm in draft-ietf-tcpm-rack + */ +-static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag) ++static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag, ++ struct rate_sample *rs) + { + struct tcp_sock *tp = tcp_sk(sk); + +@@ -3824,6 +3825,11 @@ static void tcp_process_tlp_ack(struct s + FLAG_NOT_DUP | FLAG_DATA_SACKED))) { + /* Pure dupack: original and TLP probe arrived; no loss */ + tp->tlp_high_seq = 0; ++ } else { ++ /* This ACK matches a TLP retransmit. We cannot yet tell if ++ * this ACK is for the original or the TLP retransmit. ++ */ ++ rs->is_acking_tlp_retrans_seq = 1; + } + } + +@@ -4007,7 +4013,7 @@ static int tcp_ack(struct sock *sk, cons + tcp_rack_update_reo_wnd(sk, &rs); + + if (tp->tlp_high_seq) +- tcp_process_tlp_ack(sk, ack, flag); ++ tcp_process_tlp_ack(sk, ack, flag, &rs); + + if (tcp_ack_is_dubious(sk, flag)) { + if (!(flag & (FLAG_SND_UNA_ADVANCED | +@@ -4051,7 +4057,7 @@ no_queue: + tcp_ack_probe(sk); + + if (tp->tlp_high_seq) +- tcp_process_tlp_ack(sk, ack, flag); ++ tcp_process_tlp_ack(sk, ack, flag, &rs); + return 1; + + old_ack: diff --git a/target/linux/generic/hack-6.6/601-15-bbr-v3-upstream-prep-2024-02-19-01-tcp-introduce-per-route-feature-RTAX_FEATURE_ECN_LOW.patch b/target/linux/generic/hack-6.6/601-15-bbr-v3-upstream-prep-2024-02-19-01-tcp-introduce-per-route-feature-RTAX_FEATURE_ECN_LOW.patch new file mode 100644 index 00000000000000..ec870077a31181 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-15-bbr-v3-upstream-prep-2024-02-19-01-tcp-introduce-per-route-feature-RTAX_FEATURE_ECN_LOW.patch @@ -0,0 +1,108 @@ +From a3a96f4abe4e8ae8b243ab5e490334f19fe64c7a Mon Sep 17 00:00:00 2001 +From: David Morley +Date: Fri, 14 Jul 2023 11:07:56 -0400 +Subject: [PATCH 15/19] tcp: introduce per-route feature RTAX_FEATURE_ECN_LOW + +Define and implement a new per-route feature, RTAX_FEATURE_ECN_LOW. + +This feature indicates that the given destination network is a +low-latency ECN environment, meaning both that ECN CE marks are +applied by the network using a low-latency marking threshold and also +that TCP endpoints provide precise per-data-segment ECN feedback in +ACKs (where the ACK ECE flag echoes the received CE status of all +newly-acknowledged data segments). This feature indication can be used +by congestion control algorithms to decide how to interpret ECN +signals over the given destination network. + +This feature is appropriate for datacenter-style ECN marking, such as +the ECN marking approach expected by DCTCP or BBR congestion control +modules. + +Signed-off-by: David Morley +Signed-off-by: Neal Cardwell +Signed-off-by: Yuchung Cheng +Tested-by: David Morley +Change-Id: I6bc06e9c6cb426fbae7243fc71c9a8c18175f5d3 +--- + include/net/tcp.h | 10 ++++++++++ + include/uapi/linux/rtnetlink.h | 4 +++- + net/ipv4/tcp_minisocks.c | 2 ++ + net/ipv4/tcp_output.c | 6 ++++-- + 4 files changed, 19 insertions(+), 3 deletions(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -372,6 +372,7 @@ static inline void tcp_dec_quickack_mode + #define TCP_ECN_QUEUE_CWR 2 + #define TCP_ECN_DEMAND_CWR 4 + #define TCP_ECN_SEEN 8 ++#define TCP_ECN_LOW 16 + + enum tcp_tw_status { + TCP_TW_SUCCESS = 0, +@@ -724,6 +725,15 @@ static inline void tcp_fast_path_check(s + tcp_fast_path_on(tp); + } + ++static inline void tcp_set_ecn_low_from_dst(struct sock *sk, ++ const struct dst_entry *dst) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ ++ if (dst_feature(dst, RTAX_FEATURE_ECN_LOW)) ++ tp->ecn_flags |= TCP_ECN_LOW; ++} ++ + u32 tcp_delack_max(const struct sock *sk); + + /* Compute the actual rto_min value */ +--- a/include/uapi/linux/rtnetlink.h ++++ b/include/uapi/linux/rtnetlink.h +@@ -509,9 +509,11 @@ enum { + #define RTAX_FEATURE_SACK (1 << 1) + #define RTAX_FEATURE_TIMESTAMP (1 << 2) + #define RTAX_FEATURE_ALLFRAG (1 << 3) ++#define RTAX_FEATURE_ECN_LOW (1 << 4) + + #define RTAX_FEATURE_MASK (RTAX_FEATURE_ECN | RTAX_FEATURE_SACK | \ +- RTAX_FEATURE_TIMESTAMP | RTAX_FEATURE_ALLFRAG) ++ RTAX_FEATURE_TIMESTAMP | RTAX_FEATURE_ALLFRAG \ ++ | RTAX_FEATURE_ECN_LOW) + + struct rta_session { + __u8 proto; +--- a/net/ipv4/tcp_minisocks.c ++++ b/net/ipv4/tcp_minisocks.c +@@ -434,6 +434,8 @@ void tcp_ca_openreq_child(struct sock *s + u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); + bool ca_got_dst = false; + ++ tcp_set_ecn_low_from_dst(sk, dst); ++ + if (ca_key != TCP_CA_UNSPEC) { + const struct tcp_congestion_ops *ca; + +--- a/net/ipv4/tcp_output.c ++++ b/net/ipv4/tcp_output.c +@@ -334,10 +334,9 @@ static void tcp_ecn_send_syn(struct sock + bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); + bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 || + tcp_ca_needs_ecn(sk) || bpf_needs_ecn; ++ const struct dst_entry *dst = __sk_dst_get(sk); + + if (!use_ecn) { +- const struct dst_entry *dst = __sk_dst_get(sk); +- + if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) + use_ecn = true; + } +@@ -349,6 +348,9 @@ static void tcp_ecn_send_syn(struct sock + tp->ecn_flags = TCP_ECN_OK; + if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) + INET_ECN_xmit(sk); ++ ++ if (dst) ++ tcp_set_ecn_low_from_dst(sk, dst); + } + } + diff --git a/target/linux/generic/hack-6.6/601-16-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-update-TCP-bbr-congestion-control-mod.patch b/target/linux/generic/hack-6.6/601-16-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-update-TCP-bbr-congestion-control-mod.patch new file mode 100644 index 00000000000000..1a206c3e2f63e4 --- /dev/null +++ b/target/linux/generic/hack-6.6/601-16-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-update-TCP-bbr-congestion-control-mod.patch @@ -0,0 +1,2822 @@ +From ba71521b6189a839b1152c9e015718e3e2494614 Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Tue, 11 Jun 2019 12:54:22 -0400 +Subject: [PATCH 16/19] net-tcp_bbr: v3: update TCP "bbr" congestion control + module to BBRv3 + +BBR v3 is an enhacement to the BBR v1 algorithm. It's designed to aim for lower +queues, lower loss, and better Reno/CUBIC coexistence than BBR v1. + +BBR v3 maintains the core of BBR v1: an explicit model of the network +path that is two-dimensional, adapting to estimate the (a) maximum +available bandwidth and (b) maximum safe volume of data a flow can +keep in-flight in the network. It maintains the estimated BDP as a +core guide for estimating an appropriate level of in-flight data. + +BBR v3 makes several key enhancements: + +o Its bandwidth-probing time scale is adapted, within bounds, to allow improved +coexistence with Reno and CUBIC. 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. + +o Rather than being largely agnostic to loss and ECN marks, it explicitly uses +loss and (DCTCP-style) ECN signals to maintain its model. + +o It aims for lower losses than v1 by adjusting its model to attempt to stay +within loss rate and ECN mark rate bounds (loss_thresh and ecn_thresh, +respectively). + +o It adapts to loss/ECN signals even when the application is running out of +data ("application-limited"), in case the "application-limited" flow is also +"network-limited" (the bw and/or inflight available to this flow is lower than +previously estimated when the flow ran out of data). + +o It has a three-part model: the model explicit three tracks operating points, +where an operating point is a tuple: (bandwidth, inflight). The three operating +points are: + + o latest: the latest measurement from the current round trip + o upper bound: robust, optimistic, long-term upper bound + o lower bound: robust, conservative, short-term lower bound + +These are stored in the following state variables: + + o latest: bw_latest, inflight_latest + o lo: bw_lo, inflight_lo + o hi: bw_hi[2], inflight_hi + +To gain intuition about the meaning of the three operating points, it +may help to consider the analogs in CUBIC, which has a somewhat +analogous three-part model used by its probing state machine: + + BBR param CUBIC param + ----------- ------------- + latest ~ cwnd + lo ~ ssthresh + hi ~ last_max_cwnd + +The analogy is only a loose one, though, since the BBR operating +points are calculated differently, and are 2-dimensional (bw,inflight) +rather than CUBIC's one-dimensional notion of operating point +(inflight). + +o It uses the three-part model to adapt the magnitude of its bandwidth +to match the estimated space available in the buffer, rather than (as +in BBR v1) assuming that it was always acceptable to place 0.25*BDP in +the bottleneck buffer when probing (commodity datacenter switches +commonly do not have that much buffer for WAN flows). When BBR v3 +estimates it hit a buffer limit during probing, its bandwidth probing +then starts gently in case little space is still available in the +buffer, and the accelerates, slowly at first and then rapidly if it +can grow inflight without seeing congestion signals. In such cases, +probing is bounded by inflight_hi + inflight_probe, where +inflight_probe grows as: [0, 1, 2, 4, 8, 16,...]. This allows BBR to +keep losses low and bounded if a bottleneck remains congested, while +rapidly/scalably utilizing free bandwidth when it becomes available. + +o It has a slightly revised state machine, to achieve the goals above. + BBR_BW_PROBE_UP: pushes up inflight to probe for bw/vol + BBR_BW_PROBE_DOWN: drain excess inflight from the queue + BBR_BW_PROBE_CRUISE: use pipe, w/ headroom in queue/pipe + BBR_BW_PROBE_REFILL: try refill the pipe again to 100%, leaving queue empty + +o The estimated BDP: BBR v3 continues to maintain an estimate of the +path's two-way propagation delay, by tracking a windowed min_rtt, and +coordinating (on an as-ndeeded basis) to try to expose the two-way +propagation delay by draining the bottleneck queue. + +BBR v3 continues to use its min_rtt and (currently-applicable) bandwidth +estimate to estimate the current bandwidth-delay product. The estimated BDP +still provides one important guideline for bounding inflight data. However, +because any min-filtered RTT and max-filtered bw inherently tend to both +overestimate, the estimated BDP is often too high; in this case loss or ECN +marks can ensue, in which case BBR v3 adjusts inflight_hi and inflight_lo to +adapt its sending rate and inflight down to match the available capacity of the +path. + +o Space: Note that ICSK_CA_PRIV_SIZE increased. This is because BBR v3 +requires more space. Note that much of the space is due to support for +per-socket parameterization and debugging in this release for research +and debugging. With that state removed, the full "struct bbr" is 140 +bytes, or 144 with padding. This is an increase of 40 bytes over the +existing ca_priv space. + +o Code: BBR v3 reuses many pieces from BBR v1. But it omits the following + significant pieces: + + o "packet conservation" (bbr_set_cwnd_to_recover_or_restore(), + bbr_can_grow_inflight()) + o long-term bandwidth estimator ("policer mode") + + The code layout tries to keep BBR v3 code near the bottom of the + file, so that v1-applicable code in the top does not accidentally + refer to v3 code. + +o Docs: + See the following docs for more details and diagrams decsribing the BBR v3 + algorithm: + https://datatracker.ietf.org/meeting/104/materials/slides-104-iccrg-an-update-on-bbr-00 + https://datatracker.ietf.org/meeting/102/materials/slides-102-iccrg-an-update-on-bbr-work-at-google-00 + +o Internal notes: + For this upstream rebase, Neal started from: + git show fed518041ac6:net/ipv4/tcp_bbr.c > net/ipv4/tcp_bbr.c + then removed dev instrumentation (dynamic get/set for parameters) + and code that was only used by BBRv1 + +Effort: net-tcp_bbr +Origin-9xx-SHA1: 2c84098e60bed6d67dde23cd7538c51dee273102 +Change-Id: I125cf26ba2a7a686f2fa5e87f4c2afceb65f7a05 +--- + include/net/inet_connection_sock.h | 4 +- + include/net/tcp.h | 2 +- + include/uapi/linux/inet_diag.h | 23 + + net/ipv4/Kconfig | 21 +- + net/ipv4/tcp_bbr.c | 2217 +++++++++++++++++++++------- + 5 files changed, 1742 insertions(+), 525 deletions(-) + +--- a/include/net/inet_connection_sock.h ++++ b/include/net/inet_connection_sock.h +@@ -135,8 +135,8 @@ struct inet_connection_sock { + u32 icsk_probes_tstamp; + u32 icsk_user_timeout; + +- u64 icsk_ca_priv[104 / sizeof(u64)]; +-#define ICSK_CA_PRIV_SIZE sizeof_field(struct inet_connection_sock, icsk_ca_priv) ++#define ICSK_CA_PRIV_SIZE (144) ++ u64 icsk_ca_priv[ICSK_CA_PRIV_SIZE / sizeof(u64)]; + }; + + #define ICSK_TIME_RETRANS 1 /* Retransmit timer */ +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -2272,7 +2272,7 @@ struct tcp_plb_state { + u8 consec_cong_rounds:5, /* consecutive congested rounds */ + unused:3; + u32 pause_until; /* jiffies32 when PLB can resume rerouting */ +-}; ++} __attribute__ ((__packed__)); + + static inline void tcp_plb_init(const struct sock *sk, + struct tcp_plb_state *plb) +--- a/include/uapi/linux/inet_diag.h ++++ b/include/uapi/linux/inet_diag.h +@@ -229,6 +229,29 @@ struct tcp_bbr_info { + __u32 bbr_min_rtt; /* min-filtered RTT in uSec */ + __u32 bbr_pacing_gain; /* pacing gain shifted left 8 bits */ + __u32 bbr_cwnd_gain; /* cwnd gain shifted left 8 bits */ ++ __u32 bbr_bw_hi_lsb; /* lower 32 bits of bw_hi */ ++ __u32 bbr_bw_hi_msb; /* upper 32 bits of bw_hi */ ++ __u32 bbr_bw_lo_lsb; /* lower 32 bits of bw_lo */ ++ __u32 bbr_bw_lo_msb; /* upper 32 bits of bw_lo */ ++ __u8 bbr_mode; /* current bbr_mode in state machine */ ++ __u8 bbr_phase; /* current state machine phase */ ++ __u8 unused1; /* alignment padding; not used yet */ ++ __u8 bbr_version; /* BBR algorithm version */ ++ __u32 bbr_inflight_lo; /* lower short-term data volume bound */ ++ __u32 bbr_inflight_hi; /* higher long-term data volume bound */ ++ __u32 bbr_extra_acked; /* max excess packets ACKed in epoch */ ++}; ++ ++/* TCP BBR congestion control bbr_phase as reported in netlink/ss stats. */ ++enum tcp_bbr_phase { ++ BBR_PHASE_INVALID = 0, ++ BBR_PHASE_STARTUP = 1, ++ BBR_PHASE_DRAIN = 2, ++ BBR_PHASE_PROBE_RTT = 3, ++ BBR_PHASE_PROBE_BW_UP = 4, ++ BBR_PHASE_PROBE_BW_DOWN = 5, ++ BBR_PHASE_PROBE_BW_CRUISE = 6, ++ BBR_PHASE_PROBE_BW_REFILL = 7, + }; + + union tcp_cc_info { +--- a/net/ipv4/Kconfig ++++ b/net/ipv4/Kconfig +@@ -668,15 +668,18 @@ config TCP_CONG_BBR + default n + help + +- BBR (Bottleneck Bandwidth and RTT) TCP congestion control aims to +- maximize network utilization and minimize queues. It builds an explicit +- model of the bottleneck delivery rate and path round-trip propagation +- delay. It tolerates packet loss and delay unrelated to congestion. It +- can operate over LAN, WAN, cellular, wifi, or cable modem links. 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 the fq +- ("Fair Queue") pacing packet scheduler. ++ BBR (Bottleneck Bandwidth and RTT) 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. It can operate over LAN, WAN, ++ cellular, wifi, or cable modem links, and can use shallow-threshold ++ ECN signals. It can coexist to some degree 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" +--- a/net/ipv4/tcp_bbr.c ++++ b/net/ipv4/tcp_bbr.c +@@ -1,18 +1,19 @@ +-/* Bottleneck Bandwidth and RTT (BBR) congestion control ++/* BBR (Bottleneck Bandwidth and RTT) congestion control + * +- * BBR congestion control computes the sending rate based on the delivery +- * rate (throughput) estimated from ACKs. In a nutshell: ++ * BBR is a model-based congestion control algorithm that aims for low queues, ++ * low loss, and (bounded) Reno/CUBIC coexistence. To maintain a model of the ++ * network path, it uses measurements of bandwidth and RTT, as well as (if they ++ * occur) packet loss and/or shallow-threshold ECN signals. Note that although ++ * it can use ECN or loss signals explicitly, it does not require either; it ++ * can bound its in-flight data based on its estimate of the BDP. + * +- * On each ACK, update our model of the network path: +- * bottleneck_bandwidth = windowed_max(delivered / elapsed, 10 round trips) +- * min_rtt = windowed_min(rtt, 10 seconds) +- * pacing_rate = pacing_gain * bottleneck_bandwidth +- * cwnd = max(cwnd_gain * bottleneck_bandwidth * min_rtt, 4) +- * +- * The core algorithm does not react directly to packet losses or delays, +- * although BBR may adjust the size of next send per ACK when loss is +- * observed, or adjust the sending rate if it estimates there is a +- * traffic policer, in order to keep the drop rate reasonable. ++ * The model has both higher and lower bounds for the operating range: ++ * lo: bw_lo, inflight_lo: conservative short-term lower bound ++ * hi: bw_hi, inflight_hi: robust long-term upper bound ++ * The bandwidth-probing time scale is (a) extended dynamically based on ++ * estimated BDP to improve coexistence with Reno/CUBIC; (b) bounded by ++ * an interactive wall-clock time-scale to be more scalable and responsive ++ * than Reno and CUBIC. + * + * Here is a state transition diagram for BBR: + * +@@ -65,6 +66,13 @@ + #include + #include + ++#include ++#include "tcp_dctcp.h" ++ ++#define BBR_VERSION 3 ++ ++#define bbr_param(sk,name) (bbr_ ## name) ++ + /* Scale factor for rate in pkt/uSec unit to avoid truncation in bandwidth + * estimation. The rate unit ~= (1500 bytes / 1 usec / 2^24) ~= 715 bps. + * This handles bandwidths from 0.06pps (715bps) to 256Mpps (3Tbps) in a u32. +@@ -85,36 +93,41 @@ enum bbr_mode { + BBR_PROBE_RTT, /* cut inflight to min to probe min_rtt */ + }; + ++/* How does the incoming ACK stream relate to our bandwidth probing? */ ++enum bbr_ack_phase { ++ BBR_ACKS_INIT, /* not probing; not getting probe feedback */ ++ BBR_ACKS_REFILLING, /* sending at est. bw to fill pipe */ ++ BBR_ACKS_PROBE_STARTING, /* inflight rising to probe bw */ ++ BBR_ACKS_PROBE_FEEDBACK, /* getting feedback from bw probing */ ++ BBR_ACKS_PROBE_STOPPING, /* stopped probing; still getting feedback */ ++}; ++ + /* BBR congestion control block */ + struct bbr { + u32 min_rtt_us; /* min RTT in min_rtt_win_sec window */ + u32 min_rtt_stamp; /* timestamp of min_rtt_us */ + u32 probe_rtt_done_stamp; /* end time for BBR_PROBE_RTT mode */ +- struct minmax bw; /* Max recent delivery rate in pkts/uS << 24 */ +- u32 rtt_cnt; /* count of packet-timed rounds elapsed */ ++ u32 probe_rtt_min_us; /* min RTT in probe_rtt_win_ms win */ ++ u32 probe_rtt_min_stamp; /* timestamp of probe_rtt_min_us*/ + u32 next_rtt_delivered; /* scb->tx.delivered at end of round */ + u64 cycle_mstamp; /* time of this cycle phase start */ +- u32 mode:3, /* current bbr_mode in state machine */ ++ u32 mode:2, /* current bbr_mode in state machine */ + prev_ca_state:3, /* CA state on previous ACK */ +- packet_conservation:1, /* use packet conservation? */ + round_start:1, /* start of packet-timed tx->ack round? */ ++ ce_state:1, /* If most recent data has CE bit set */ ++ bw_probe_up_rounds:5, /* cwnd-limited rounds in PROBE_UP */ ++ try_fast_path:1, /* can we take fast path? */ + idle_restart:1, /* restarting after idle? */ + probe_rtt_round_done:1, /* a BBR_PROBE_RTT round at 4 pkts? */ +- unused:13, +- lt_is_sampling:1, /* taking long-term ("LT") samples now? */ +- lt_rtt_cnt:7, /* round trips in long-term interval */ +- lt_use_bw:1; /* use lt_bw as our bw estimate? */ +- u32 lt_bw; /* LT est delivery rate in pkts/uS << 24 */ +- u32 lt_last_delivered; /* LT intvl start: tp->delivered */ +- u32 lt_last_stamp; /* LT intvl start: tp->delivered_mstamp */ +- u32 lt_last_lost; /* LT intvl start: tp->lost */ ++ init_cwnd:7, /* initial cwnd */ ++ unused_1:10; + u32 pacing_gain:10, /* current gain for setting pacing rate */ + cwnd_gain:10, /* current gain for setting cwnd */ + full_bw_reached:1, /* reached full bw in Startup? */ + full_bw_cnt:2, /* number of rounds without large bw gains */ +- cycle_idx:3, /* current index in pacing_gain cycle array */ ++ cycle_idx:2, /* current index in pacing_gain cycle array */ + has_seen_rtt:1, /* have we seen an RTT sample yet? */ +- unused_b:5; ++ unused_2:6; + u32 prior_cwnd; /* prior cwnd upon entering loss recovery */ + u32 full_bw; /* recent bw, to estimate if pipe is full */ + +@@ -124,19 +137,67 @@ struct bbr { + u32 ack_epoch_acked:20, /* packets (S)ACKed in sampling epoch */ + extra_acked_win_rtts:5, /* age of extra_acked, in round trips */ + extra_acked_win_idx:1, /* current index in extra_acked array */ +- unused_c:6; ++ /* BBR v3 state: */ ++ full_bw_now:1, /* recently reached full bw plateau? */ ++ startup_ecn_rounds:2, /* consecutive hi ECN STARTUP rounds */ ++ loss_in_cycle:1, /* packet loss in this cycle? */ ++ ecn_in_cycle:1, /* ECN in this cycle? */ ++ unused_3:1; ++ u32 loss_round_delivered; /* scb->tx.delivered ending loss round */ ++ u32 undo_bw_lo; /* bw_lo before latest losses */ ++ u32 undo_inflight_lo; /* inflight_lo before latest losses */ ++ u32 undo_inflight_hi; /* inflight_hi before latest losses */ ++ u32 bw_latest; /* max delivered bw in last round trip */ ++ u32 bw_lo; /* lower bound on sending bandwidth */ ++ u32 bw_hi[2]; /* max recent measured bw sample */ ++ u32 inflight_latest; /* max delivered data in last round trip */ ++ u32 inflight_lo; /* lower bound of inflight data range */ ++ u32 inflight_hi; /* upper bound of inflight data range */ ++ u32 bw_probe_up_cnt; /* packets delivered per inflight_hi incr */ ++ u32 bw_probe_up_acks; /* packets (S)ACKed since inflight_hi incr */ ++ u32 probe_wait_us; /* PROBE_DOWN until next clock-driven probe */ ++ u32 prior_rcv_nxt; /* tp->rcv_nxt when CE state last changed */ ++ u32 ecn_eligible:1, /* sender can use ECN (RTT, handshake)? */ ++ ecn_alpha:9, /* EWMA delivered_ce/delivered; 0..256 */ ++ bw_probe_samples:1, /* rate samples reflect bw probing? */ ++ prev_probe_too_high:1, /* did last PROBE_UP go too high? */ ++ stopped_risky_probe:1, /* last PROBE_UP stopped due to risk? */ ++ rounds_since_probe:8, /* packet-timed rounds since probed bw */ ++ loss_round_start:1, /* loss_round_delivered round trip? */ ++ loss_in_round:1, /* loss marked in this round trip? */ ++ ecn_in_round:1, /* ECN marked in this round trip? */ ++ ack_phase:3, /* bbr_ack_phase: meaning of ACKs */ ++ loss_events_in_round:4,/* losses in STARTUP round */ ++ initialized:1; /* has bbr_init() been called? */ ++ u32 alpha_last_delivered; /* tp->delivered at alpha update */ ++ u32 alpha_last_delivered_ce; /* tp->delivered_ce at alpha update */ ++ ++ u8 unused_4; /* to preserve alignment */ ++ struct tcp_plb_state plb; + }; + +-#define CYCLE_LEN 8 /* number of phases in a pacing gain cycle */ ++struct bbr_context { ++ u32 sample_bw; ++}; + +-/* Window length of bw filter (in rounds): */ +-static const int bbr_bw_rtts = CYCLE_LEN + 2; + /* Window length of min_rtt filter (in sec): */ + static const u32 bbr_min_rtt_win_sec = 10; + /* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode: */ + static const u32 bbr_probe_rtt_mode_ms = 200; +-/* Skip TSO below the following bandwidth (bits/sec): */ +-static const int bbr_min_tso_rate = 1200000; ++/* Window length of probe_rtt_min_us filter (in ms), and consequently the ++ * typical interval between PROBE_RTT mode entries. The default is 5000ms. ++ * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC ++ */ ++static const u32 bbr_probe_rtt_win_ms = 5000; ++/* Proportion of cwnd to estimated BDP in PROBE_RTT, in units of BBR_UNIT: */ ++static const u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2; ++ ++/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting ++ * in bigger TSO bursts. We cut the RTT-based allowance in half ++ * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance ++ * is below 1500 bytes after 6 * ~500 usec = 3ms. ++ */ ++static const u32 bbr_tso_rtt_shift = 9; + + /* Pace at ~1% below estimated bw, on average, to reduce queue at bottleneck. + * In order to help drive the network toward lower queues and low latency while +@@ -146,13 +207,15 @@ static const int bbr_min_tso_rate = 1200 + */ + static const int bbr_pacing_margin_percent = 1; + +-/* We use a high_gain value of 2/ln(2) because it's the smallest pacing gain ++/* We use a startup_pacing_gain of 4*ln(2) because it's the smallest value + * that will allow a smoothly increasing pacing rate that will double each RTT + * and send the same number of packets per RTT that an un-paced, slow-starting + * Reno or CUBIC flow would: + */ +-static const int bbr_high_gain = BBR_UNIT * 2885 / 1000 + 1; +-/* The pacing gain of 1/high_gain in BBR_DRAIN is calculated to typically drain ++static const int bbr_startup_pacing_gain = BBR_UNIT * 277 / 100 + 1; ++/* The gain for deriving startup cwnd: */ ++static const int bbr_startup_cwnd_gain = BBR_UNIT * 2; ++/* The pacing gain in BBR_DRAIN is calculated to typically drain + * the queue created in BBR_STARTUP in a single round: + */ + static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885; +@@ -160,13 +223,17 @@ static const int bbr_drain_gain = BBR_UN + static const int bbr_cwnd_gain = BBR_UNIT * 2; + /* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw: */ + static const int bbr_pacing_gain[] = { +- BBR_UNIT * 5 / 4, /* probe for more available bw */ +- BBR_UNIT * 3 / 4, /* drain queue and/or yield bw to other flows */ +- BBR_UNIT, BBR_UNIT, BBR_UNIT, /* cruise at 1.0*bw to utilize pipe, */ +- BBR_UNIT, BBR_UNIT, BBR_UNIT /* without creating excess queue... */ ++ BBR_UNIT * 5 / 4, /* UP: probe for more available bw */ ++ BBR_UNIT * 91 / 100, /* DOWN: drain queue and/or yield bw */ ++ BBR_UNIT, /* CRUISE: try to use pipe w/ some headroom */ ++ BBR_UNIT, /* REFILL: refill pipe to estimated 100% */ ++}; ++enum bbr_pacing_gain_phase { ++ BBR_BW_PROBE_UP = 0, /* push up inflight to probe for bw/vol */ ++ BBR_BW_PROBE_DOWN = 1, /* drain excess inflight from the queue */ ++ BBR_BW_PROBE_CRUISE = 2, /* use pipe, w/ headroom in queue/pipe */ ++ BBR_BW_PROBE_REFILL = 3, /* v2: refill the pipe again to 100% */ + }; +-/* Randomize the starting gain cycling phase over N phases: */ +-static const u32 bbr_cycle_rand = 7; + + /* Try to keep at least this many packets in flight, if things go smoothly. For + * smooth functioning, a sliding window protocol ACKing every other packet +@@ -174,24 +241,12 @@ static const u32 bbr_cycle_rand = 7; + */ + static const u32 bbr_cwnd_min_target = 4; + +-/* To estimate if BBR_STARTUP mode (i.e. high_gain) has filled pipe... */ ++/* To estimate if BBR_STARTUP or BBR_BW_PROBE_UP has filled pipe... */ + /* If bw has increased significantly (1.25x), there may be more bw available: */ + static const u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4; + /* But after 3 rounds w/o significant bw growth, estimate pipe is full: */ + static const u32 bbr_full_bw_cnt = 3; + +-/* "long-term" ("LT") bandwidth estimator parameters... */ +-/* The minimum number of rounds in an LT bw sampling interval: */ +-static const u32 bbr_lt_intvl_min_rtts = 4; +-/* If lost/delivered ratio > 20%, interval is "lossy" and we may be policed: */ +-static const u32 bbr_lt_loss_thresh = 50; +-/* If 2 intervals have a bw ratio <= 1/8, their bw is "consistent": */ +-static const u32 bbr_lt_bw_ratio = BBR_UNIT / 8; +-/* If 2 intervals have a bw diff <= 4 Kbit/sec their bw is "consistent": */ +-static const u32 bbr_lt_bw_diff = 4000 / 8; +-/* If we estimate we're policed, use lt_bw for this many round trips: */ +-static const u32 bbr_lt_bw_max_rtts = 48; +- + /* Gain factor for adding extra_acked to target cwnd: */ + static const int bbr_extra_acked_gain = BBR_UNIT; + /* Window length of extra_acked window. */ +@@ -201,8 +256,121 @@ static const u32 bbr_ack_epoch_acked_res + /* Time period for clamping cwnd increment due to ack aggregation */ + static const u32 bbr_extra_acked_max_us = 100 * 1000; + ++/* Flags to control BBR ECN-related behavior... */ ++ ++/* Ensure ACKs only ACK packets with consistent ECN CE status? */ ++static const bool bbr_precise_ece_ack = true; ++ ++/* Max RTT (in usec) at which to use sender-side ECN logic. ++ * Disabled when 0 (ECN allowed at any RTT). ++ */ ++static const u32 bbr_ecn_max_rtt_us = 5000; ++ ++/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE. ++ * No loss response when 0. ++ */ ++static const u32 bbr_beta = BBR_UNIT * 30 / 100; ++ ++/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE (1/16 = 6.25%) */ ++static const u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16; ++ ++/* The initial value for ecn_alpha; 1.0 allows a flow to respond quickly ++ * to congestion if the bottleneck is congested when the flow starts up. ++ */ ++static const u32 bbr_ecn_alpha_init = BBR_UNIT; ++ ++/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE. ++ * No ECN based bounding when 0. ++ */ ++static const u32 bbr_ecn_factor = BBR_UNIT * 1 / 3; /* 1/3 = 33% */ ++ ++/* Estimate bw probing has gone too far if CE ratio exceeds this threshold. ++ * Scaled by BBR_SCALE. Disabled when 0. ++ */ ++static const u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2; /* 1/2 = 50% */ ++ ++/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN ++ * clears then make the first round's increment to inflight_hi the following ++ * fraction of inflight_hi. ++ */ ++static const u32 bbr_ecn_reprobe_gain = BBR_UNIT * 1 / 2; ++ ++/* Estimate bw probing has gone too far if loss rate exceeds this level. */ ++static const u32 bbr_loss_thresh = BBR_UNIT * 2 / 100; /* 2% loss */ ++ ++/* Slow down for a packet loss recovered by TLP? */ ++static const bool bbr_loss_probe_recovery = true; ++ ++/* Exit STARTUP if number of loss marking events in a Recovery round is >= N, ++ * and loss rate is higher than bbr_loss_thresh. ++ * Disabled if 0. ++ */ ++static const u32 bbr_full_loss_cnt = 6; ++ ++/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh ++ * meets this count. ++ */ ++static const u32 bbr_full_ecn_cnt = 2; ++ ++/* Fraction of unutilized headroom to try to leave in path upon high loss. */ ++static const u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100; ++ ++/* How much do we increase cwnd_gain when probing for bandwidth in ++ * BBR_BW_PROBE_UP? This specifies the increment in units of ++ * BBR_UNIT/4. The default is 1, meaning 0.25. ++ * The min value is 0 (meaning 0.0); max is 3 (meaning 0.75). ++ */ ++static const u32 bbr_bw_probe_cwnd_gain = 1; ++ ++/* Max number of packet-timed rounds to wait before probing for bandwidth. If ++ * we want to tolerate 1% random loss per round, and not have this cut our ++ * inflight too much, we must probe for bw periodically on roughly this scale. ++ * If low, limits Reno/CUBIC coexistence; if high, limits loss tolerance. ++ * We aim to be fair with Reno/CUBIC up to a BDP of at least: ++ * BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets ++ */ ++static const u32 bbr_bw_probe_max_rounds = 63; ++ ++/* Max amount of randomness to inject in round counting for Reno-coexistence. ++ */ ++static const u32 bbr_bw_probe_rand_rounds = 2; ++ ++/* Use BBR-native probe time scale starting at this many usec. ++ * We aim to be fair with Reno/CUBIC up to an inter-loss time epoch of at least: ++ * BDP*RTT = 25Mbps * .030sec /(1514bytes) * 0.030sec = 1.9 secs ++ */ ++static const u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC; /* 2 secs */ ++ ++/* Use BBR-native probes spread over this many usec: */ ++static const u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC; /* 1 secs */ ++ ++/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */ ++static const bool bbr_fast_path = true; ++ ++/* Use fast ack mode? */ ++static const bool bbr_fast_ack_mode = true; ++ ++static u32 bbr_max_bw(const struct sock *sk); ++static u32 bbr_bw(const struct sock *sk); ++static void bbr_exit_probe_rtt(struct sock *sk); ++static void bbr_reset_congestion_signals(struct sock *sk); ++static void bbr_run_loss_probe_recovery(struct sock *sk); ++ + static void bbr_check_probe_rtt_done(struct sock *sk); + ++/* This connection can use ECN if both endpoints have signaled ECN support in ++ * the handshake and the per-route settings indicated this is a ++ * shallow-threshold ECN environment, meaning both: ++ * (a) ECN CE marks indicate low-latency/shallow-threshold congestion, and ++ * (b) TCP endpoints provide precise ACKs that only ACK data segments ++ * with consistent ECN CE status ++ */ ++static bool bbr_can_use_ecn(const struct sock *sk) ++{ ++ return (tcp_sk(sk)->ecn_flags & TCP_ECN_OK) && ++ (tcp_sk(sk)->ecn_flags & TCP_ECN_LOW); ++} ++ + /* Do we estimate that STARTUP filled the pipe? */ + static bool bbr_full_bw_reached(const struct sock *sk) + { +@@ -214,17 +382,17 @@ static bool bbr_full_bw_reached(const st + /* Return the windowed max recent bandwidth sample, in pkts/uS << BW_SCALE. */ + static u32 bbr_max_bw(const struct sock *sk) + { +- struct bbr *bbr = inet_csk_ca(sk); ++ const struct bbr *bbr = inet_csk_ca(sk); + +- return minmax_get(&bbr->bw); ++ return max(bbr->bw_hi[0], bbr->bw_hi[1]); + } + + /* Return the estimated bandwidth of the path, in pkts/uS << BW_SCALE. */ + static u32 bbr_bw(const struct sock *sk) + { +- struct bbr *bbr = inet_csk_ca(sk); ++ const struct bbr *bbr = inet_csk_ca(sk); + +- return bbr->lt_use_bw ? bbr->lt_bw : bbr_max_bw(sk); ++ return min(bbr_max_bw(sk), bbr->bw_lo); + } + + /* Return maximum extra acked in past k-2k round trips, +@@ -241,15 +409,23 @@ static u16 bbr_extra_acked(const struct + * The order here is chosen carefully to avoid overflow of u64. This should + * work for input rates of up to 2.9Tbit/sec and gain of 2.89x. + */ +-static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain) ++static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain, ++ int margin) + { + unsigned int mss = tcp_sk(sk)->mss_cache; + + rate *= mss; + rate *= gain; + rate >>= BBR_SCALE; +- rate *= USEC_PER_SEC / 100 * (100 - bbr_pacing_margin_percent); +- return rate >> BW_SCALE; ++ rate *= USEC_PER_SEC / 100 * (100 - margin); ++ rate >>= BW_SCALE; ++ rate = max(rate, 1ULL); ++ return rate; ++} ++ ++static u64 bbr_bw_bytes_per_sec(struct sock *sk, u64 rate) ++{ ++ return bbr_rate_bytes_per_sec(sk, rate, BBR_UNIT, 0); + } + + /* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */ +@@ -257,12 +433,13 @@ static unsigned long bbr_bw_to_pacing_ra + { + u64 rate = bw; + +- rate = bbr_rate_bytes_per_sec(sk, rate, gain); ++ 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. */ ++/* Initialize pacing rate to: startup_pacing_gain * init_cwnd / RTT. */ + static void bbr_init_pacing_rate_from_rtt(struct sock *sk) + { + struct tcp_sock *tp = tcp_sk(sk); +@@ -278,7 +455,8 @@ static void bbr_init_pacing_rate_from_rt + } + bw = (u64)tcp_snd_cwnd(tp) * BW_UNIT; + do_div(bw, rtt_us); +- sk->sk_pacing_rate = bbr_bw_to_pacing_rate(sk, bw, bbr_high_gain); ++ sk->sk_pacing_rate = ++ bbr_bw_to_pacing_rate(sk, bw, bbr_param(sk, startup_pacing_gain)); + } + + /* Pace using current bw estimate and a gain factor. */ +@@ -294,31 +472,38 @@ static void bbr_set_pacing_rate(struct s + 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. ++/* Return the number of segments BBR would like in a TSO/GSO skb, given a ++ * particular max gso size as a constraint. TODO: make this simpler and more ++ * consistent by switching bbr to just call tcp_tso_autosize(). + */ + static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now, + u32 gso_max_size) + { +- u32 segs; ++ 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_param(sk, tso_rtt_shift)) { ++ r = bbr->min_rtt_us >> bbr_param(sk, tso_rtt_shift); ++ if (r < BITS_PER_TYPE(u32)) /* prevent undefined behavior */ ++ bytes += GSO_LEGACY_MAX_SIZE >> r; ++ } ++ + bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER); +- segs = max_t(u32, bytes / mss_now, bbr_min_tso_segs(sk)); ++ segs = max_t(u32, bytes / mss_now, ++ sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); + return segs; + } + + /* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */ +-static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now) ++__bpf_kfunc static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now) + { + return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size); + } +@@ -328,7 +513,7 @@ static u32 bbr_tso_segs_goal(struct sock + { + struct tcp_sock *tp = tcp_sk(sk); + +- return bbr_tso_segs_generic(sk, tp->mss_cache, GSO_MAX_SIZE); ++ 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 */ +@@ -348,7 +533,9 @@ __bpf_kfunc static void bbr_cwnd_event(s + struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); + +- if (event == CA_EVENT_TX_START && tp->app_limited) { ++ if (event == CA_EVENT_TX_START) { ++ if (!tp->app_limited) ++ return; + bbr->idle_restart = 1; + bbr->ack_epoch_mstamp = tp->tcp_mstamp; + bbr->ack_epoch_acked = 0; +@@ -359,6 +546,16 @@ __bpf_kfunc static void bbr_cwnd_event(s + bbr_set_pacing_rate(sk, bbr_bw(sk), BBR_UNIT); + else if (bbr->mode == BBR_PROBE_RTT) + bbr_check_probe_rtt_done(sk); ++ } else if ((event == CA_EVENT_ECN_IS_CE || ++ event == CA_EVENT_ECN_NO_CE) && ++ bbr_can_use_ecn(sk) && ++ bbr_param(sk, precise_ece_ack)) { ++ u32 state = bbr->ce_state; ++ dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state); ++ bbr->ce_state = state; ++ } else if (event == CA_EVENT_TLP_RECOVERY && ++ bbr_param(sk, loss_probe_recovery)) { ++ bbr_run_loss_probe_recovery(sk); + } + } + +@@ -381,10 +578,10 @@ static u32 bbr_bdp(struct sock *sk, u32 + * default. This should only happen when the connection is not using TCP + * timestamps and has retransmitted all of the SYN/SYNACK/data packets + * ACKed so far. In this case, an RTO can cut cwnd to 1, in which +- * case we need to slow-start up toward something safe: TCP_INIT_CWND. ++ * case we need to slow-start up toward something safe: initial cwnd. + */ + if (unlikely(bbr->min_rtt_us == ~0U)) /* no valid RTT samples yet? */ +- return TCP_INIT_CWND; /* be safe: cap at default initial cwnd*/ ++ return bbr->init_cwnd; /* be safe: cap at initial cwnd */ + + w = (u64)bw * bbr->min_rtt_us; + +@@ -401,23 +598,23 @@ static u32 bbr_bdp(struct sock *sk, u32 + * - one skb in sending host Qdisc, + * - one skb in sending host TSO/GSO engine + * - one skb being received by receiver host LRO/GRO/delayed-ACK engine +- * Don't worry, at low rates (bbr_min_tso_rate) this won't bloat cwnd because +- * in such cases tso_segs_goal is 1. The minimum cwnd is 4 packets, ++ * Don't worry, at low rates this won't bloat cwnd because ++ * in such cases tso_segs_goal is small. The minimum cwnd is 4 packets, + * which allows 2 outstanding 2-packet sequences, to try to keep pipe + * full even with ACK-every-other-packet delayed ACKs. + */ + static u32 bbr_quantization_budget(struct sock *sk, u32 cwnd) + { + struct bbr *bbr = inet_csk_ca(sk); ++ u32 tso_segs_goal; + +- /* Allow enough full-sized skbs in flight to utilize end systems. */ +- cwnd += 3 * bbr_tso_segs_goal(sk); +- +- /* Reduce delayed ACKs by rounding up cwnd to the next even number. */ +- cwnd = (cwnd + 1) & ~1U; ++ tso_segs_goal = 3 * bbr_tso_segs_goal(sk); + ++ /* Allow enough full-sized skbs in flight to utilize end systems. */ ++ cwnd = max_t(u32, cwnd, tso_segs_goal); ++ cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target)); + /* Ensure gain cycling gets inflight above BDP even for small BDPs. */ +- if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == 0) ++ if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) + cwnd += 2; + + return cwnd; +@@ -472,10 +669,10 @@ static u32 bbr_ack_aggregation_cwnd(stru + { + u32 max_aggr_cwnd, aggr_cwnd = 0; + +- if (bbr_extra_acked_gain && bbr_full_bw_reached(sk)) { ++ if (bbr_param(sk, extra_acked_gain)) { + max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us) + / BW_UNIT; +- aggr_cwnd = (bbr_extra_acked_gain * bbr_extra_acked(sk)) ++ aggr_cwnd = (bbr_param(sk, extra_acked_gain) * bbr_extra_acked(sk)) + >> BBR_SCALE; + aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd); + } +@@ -483,66 +680,27 @@ static u32 bbr_ack_aggregation_cwnd(stru + return aggr_cwnd; + } + +-/* An optimization in BBR to reduce losses: On the first round of recovery, we +- * follow the packet conservation principle: send P packets per P packets acked. +- * After that, we slow-start and send at most 2*P packets per P packets acked. +- * After recovery finishes, or upon undo, we restore the cwnd we had when +- * recovery started (capped by the target cwnd based on estimated BDP). +- * +- * TODO(ycheng/ncardwell): implement a rate-based approach. +- */ +-static bool bbr_set_cwnd_to_recover_or_restore( +- struct sock *sk, const struct rate_sample *rs, u32 acked, u32 *new_cwnd) ++/* Returns the cwnd for PROBE_RTT mode. */ ++static u32 bbr_probe_rtt_cwnd(struct sock *sk) + { +- struct tcp_sock *tp = tcp_sk(sk); +- struct bbr *bbr = inet_csk_ca(sk); +- u8 prev_state = bbr->prev_ca_state, state = inet_csk(sk)->icsk_ca_state; +- u32 cwnd = tcp_snd_cwnd(tp); +- +- /* An ACK for P pkts should release at most 2*P packets. We do this +- * in two steps. First, here we deduct the number of lost packets. +- * Then, in bbr_set_cwnd() we slow start up toward the target cwnd. +- */ +- if (rs->losses > 0) +- cwnd = max_t(s32, cwnd - rs->losses, 1); +- +- if (state == TCP_CA_Recovery && prev_state != TCP_CA_Recovery) { +- /* Starting 1st round of Recovery, so do packet conservation. */ +- bbr->packet_conservation = 1; +- bbr->next_rtt_delivered = tp->delivered; /* start round now */ +- /* Cut unused cwnd from app behavior, TSQ, or TSO deferral: */ +- cwnd = tcp_packets_in_flight(tp) + acked; +- } else if (prev_state >= TCP_CA_Recovery && state < TCP_CA_Recovery) { +- /* Exiting loss recovery; restore cwnd saved before recovery. */ +- cwnd = max(cwnd, bbr->prior_cwnd); +- bbr->packet_conservation = 0; +- } +- bbr->prev_ca_state = state; +- +- if (bbr->packet_conservation) { +- *new_cwnd = max(cwnd, tcp_packets_in_flight(tp) + acked); +- return true; /* yes, using packet conservation */ +- } +- *new_cwnd = cwnd; +- return false; ++ return max_t(u32, bbr_param(sk, cwnd_min_target), ++ bbr_bdp(sk, bbr_bw(sk), bbr_param(sk, probe_rtt_cwnd_gain))); + } + + /* Slow-start up toward target cwnd (if bw estimate is growing, or packet loss + * has drawn us down below target), or snap down to target if we're above it. + */ + static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs, +- u32 acked, u32 bw, int gain) ++ u32 acked, u32 bw, int gain, u32 cwnd, ++ struct bbr_context *ctx) + { + struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); +- u32 cwnd = tcp_snd_cwnd(tp), target_cwnd = 0; ++ u32 target_cwnd = 0; + + if (!acked) + goto done; /* no packet fully ACKed; just apply caps */ + +- if (bbr_set_cwnd_to_recover_or_restore(sk, rs, acked, &cwnd)) +- goto done; +- + target_cwnd = bbr_bdp(sk, bw, gain); + + /* Increment the cwnd to account for excess ACKed data that seems +@@ -551,74 +709,26 @@ static void bbr_set_cwnd(struct sock *sk + target_cwnd += bbr_ack_aggregation_cwnd(sk); + target_cwnd = bbr_quantization_budget(sk, target_cwnd); + +- /* If we're below target cwnd, slow start cwnd toward target cwnd. */ +- if (bbr_full_bw_reached(sk)) /* only cut cwnd if we filled the pipe */ +- cwnd = min(cwnd + acked, target_cwnd); +- else if (cwnd < target_cwnd || tp->delivered < TCP_INIT_CWND) +- cwnd = cwnd + acked; +- cwnd = max(cwnd, bbr_cwnd_min_target); ++ /* Update cwnd and enable fast path if cwnd reaches target_cwnd. */ ++ bbr->try_fast_path = 0; ++ if (bbr_full_bw_reached(sk)) { /* only cut cwnd if we filled the pipe */ ++ cwnd += acked; ++ if (cwnd >= target_cwnd) { ++ cwnd = target_cwnd; ++ bbr->try_fast_path = 1; ++ } ++ } else if (cwnd < target_cwnd || cwnd < 2 * bbr->init_cwnd) { ++ cwnd += acked; ++ } else { ++ bbr->try_fast_path = 1; ++ } + ++ cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target)); + done: +- tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp)); /* apply global cap */ ++ tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp)); /* global cap */ + if (bbr->mode == BBR_PROBE_RTT) /* drain queue, refresh min_rtt */ +- tcp_snd_cwnd_set(tp, min(tcp_snd_cwnd(tp), bbr_cwnd_min_target)); +-} +- +-/* End cycle phase if it's time and/or we hit the phase's in-flight target. */ +-static bool bbr_is_next_cycle_phase(struct sock *sk, +- const struct rate_sample *rs) +-{ +- struct tcp_sock *tp = tcp_sk(sk); +- struct bbr *bbr = inet_csk_ca(sk); +- bool is_full_length = +- tcp_stamp_us_delta(tp->delivered_mstamp, bbr->cycle_mstamp) > +- bbr->min_rtt_us; +- u32 inflight, bw; +- +- /* The pacing_gain of 1.0 paces at the estimated bw to try to fully +- * use the pipe without increasing the queue. +- */ +- if (bbr->pacing_gain == BBR_UNIT) +- return is_full_length; /* just use wall clock time */ +- +- inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight); +- bw = bbr_max_bw(sk); +- +- /* A pacing_gain > 1.0 probes for bw by trying to raise inflight to at +- * least pacing_gain*BDP; this may take more than min_rtt if min_rtt is +- * small (e.g. on a LAN). We do not persist if packets are lost, since +- * a path with small buffers may not hold that much. +- */ +- if (bbr->pacing_gain > BBR_UNIT) +- return is_full_length && +- (rs->losses || /* perhaps pacing_gain*BDP won't fit */ +- inflight >= bbr_inflight(sk, bw, bbr->pacing_gain)); +- +- /* A pacing_gain < 1.0 tries to drain extra queue we added if bw +- * probing didn't find more bw. If inflight falls to match BDP then we +- * estimate queue is drained; persisting would underutilize the pipe. +- */ +- return is_full_length || +- inflight <= bbr_inflight(sk, bw, BBR_UNIT); +-} +- +-static void bbr_advance_cycle_phase(struct sock *sk) +-{ +- struct tcp_sock *tp = tcp_sk(sk); +- struct bbr *bbr = inet_csk_ca(sk); +- +- bbr->cycle_idx = (bbr->cycle_idx + 1) & (CYCLE_LEN - 1); +- bbr->cycle_mstamp = tp->delivered_mstamp; +-} +- +-/* Gain cycling: cycle pacing gain to converge to fair share of available bw. */ +-static void bbr_update_cycle_phase(struct sock *sk, +- const struct rate_sample *rs) +-{ +- struct bbr *bbr = inet_csk_ca(sk); +- +- if (bbr->mode == BBR_PROBE_BW && bbr_is_next_cycle_phase(sk, rs)) +- bbr_advance_cycle_phase(sk); ++ tcp_snd_cwnd_set(tp, min_t(u32, tcp_snd_cwnd(tp), ++ bbr_probe_rtt_cwnd(sk))); + } + + static void bbr_reset_startup_mode(struct sock *sk) +@@ -628,191 +738,49 @@ static void bbr_reset_startup_mode(struc + bbr->mode = BBR_STARTUP; + } + +-static void bbr_reset_probe_bw_mode(struct sock *sk) +-{ +- struct bbr *bbr = inet_csk_ca(sk); +- +- bbr->mode = BBR_PROBE_BW; +- bbr->cycle_idx = CYCLE_LEN - 1 - get_random_u32_below(bbr_cycle_rand); +- bbr_advance_cycle_phase(sk); /* flip to next phase of gain cycle */ +-} +- +-static void bbr_reset_mode(struct sock *sk) +-{ +- if (!bbr_full_bw_reached(sk)) +- bbr_reset_startup_mode(sk); +- else +- bbr_reset_probe_bw_mode(sk); +-} +- +-/* Start a new long-term sampling interval. */ +-static void bbr_reset_lt_bw_sampling_interval(struct sock *sk) +-{ +- struct tcp_sock *tp = tcp_sk(sk); +- struct bbr *bbr = inet_csk_ca(sk); +- +- bbr->lt_last_stamp = div_u64(tp->delivered_mstamp, USEC_PER_MSEC); +- bbr->lt_last_delivered = tp->delivered; +- bbr->lt_last_lost = tp->lost; +- bbr->lt_rtt_cnt = 0; +-} +- +-/* Completely reset long-term bandwidth sampling. */ +-static void bbr_reset_lt_bw_sampling(struct sock *sk) +-{ +- struct bbr *bbr = inet_csk_ca(sk); +- +- bbr->lt_bw = 0; +- bbr->lt_use_bw = 0; +- bbr->lt_is_sampling = false; +- bbr_reset_lt_bw_sampling_interval(sk); +-} +- +-/* Long-term bw sampling interval is done. Estimate whether we're policed. */ +-static void bbr_lt_bw_interval_done(struct sock *sk, u32 bw) +-{ +- struct bbr *bbr = inet_csk_ca(sk); +- u32 diff; +- +- if (bbr->lt_bw) { /* do we have bw from a previous interval? */ +- /* Is new bw close to the lt_bw from the previous interval? */ +- diff = abs(bw - bbr->lt_bw); +- if ((diff * BBR_UNIT <= bbr_lt_bw_ratio * bbr->lt_bw) || +- (bbr_rate_bytes_per_sec(sk, diff, BBR_UNIT) <= +- bbr_lt_bw_diff)) { +- /* All criteria are met; estimate we're policed. */ +- bbr->lt_bw = (bw + bbr->lt_bw) >> 1; /* avg 2 intvls */ +- bbr->lt_use_bw = 1; +- bbr->pacing_gain = BBR_UNIT; /* try to avoid drops */ +- bbr->lt_rtt_cnt = 0; +- return; +- } +- } +- bbr->lt_bw = bw; +- bbr_reset_lt_bw_sampling_interval(sk); +-} +- +-/* Token-bucket traffic policers are common (see "An Internet-Wide Analysis of +- * Traffic Policing", SIGCOMM 2016). BBR detects token-bucket policers and +- * explicitly models their policed rate, to reduce unnecessary losses. We +- * estimate that we're policed if we see 2 consecutive sampling intervals with +- * consistent throughput and high packet loss. If we think we're being policed, +- * set lt_bw to the "long-term" average delivery rate from those 2 intervals. ++/* See if we have reached next round trip. Upon start of the new round, ++ * returns packets delivered since previous round start plus this ACK. + */ +-static void bbr_lt_bw_sampling(struct sock *sk, const struct rate_sample *rs) ++static u32 bbr_update_round_start(struct sock *sk, ++ const struct rate_sample *rs, struct bbr_context *ctx) + { + struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); +- u32 lost, delivered; +- u64 bw; +- u32 t; +- +- if (bbr->lt_use_bw) { /* already using long-term rate, lt_bw? */ +- if (bbr->mode == BBR_PROBE_BW && bbr->round_start && +- ++bbr->lt_rtt_cnt >= bbr_lt_bw_max_rtts) { +- bbr_reset_lt_bw_sampling(sk); /* stop using lt_bw */ +- bbr_reset_probe_bw_mode(sk); /* restart gain cycling */ +- } +- return; +- } +- +- /* Wait for the first loss before sampling, to let the policer exhaust +- * its tokens and estimate the steady-state rate allowed by the policer. +- * Starting samples earlier includes bursts that over-estimate the bw. +- */ +- if (!bbr->lt_is_sampling) { +- if (!rs->losses) +- return; +- bbr_reset_lt_bw_sampling_interval(sk); +- bbr->lt_is_sampling = true; +- } +- +- /* To avoid underestimates, reset sampling if we run out of data. */ +- if (rs->is_app_limited) { +- bbr_reset_lt_bw_sampling(sk); +- return; +- } +- +- if (bbr->round_start) +- bbr->lt_rtt_cnt++; /* count round trips in this interval */ +- if (bbr->lt_rtt_cnt < bbr_lt_intvl_min_rtts) +- return; /* sampling interval needs to be longer */ +- if (bbr->lt_rtt_cnt > 4 * bbr_lt_intvl_min_rtts) { +- bbr_reset_lt_bw_sampling(sk); /* interval is too long */ +- return; +- } +- +- /* End sampling interval when a packet is lost, so we estimate the +- * policer tokens were exhausted. Stopping the sampling before the +- * tokens are exhausted under-estimates the policed rate. +- */ +- if (!rs->losses) +- return; +- +- /* Calculate packets lost and delivered in sampling interval. */ +- lost = tp->lost - bbr->lt_last_lost; +- delivered = tp->delivered - bbr->lt_last_delivered; +- /* Is loss rate (lost/delivered) >= lt_loss_thresh? If not, wait. */ +- if (!delivered || (lost << BBR_SCALE) < bbr_lt_loss_thresh * delivered) +- return; +- +- /* Find average delivery rate in this sampling interval. */ +- t = div_u64(tp->delivered_mstamp, USEC_PER_MSEC) - bbr->lt_last_stamp; +- if ((s32)t < 1) +- return; /* interval is less than one ms, so wait */ +- /* Check if can multiply without overflow */ +- if (t >= ~0U / USEC_PER_MSEC) { +- bbr_reset_lt_bw_sampling(sk); /* interval too long; reset */ +- return; +- } +- t *= USEC_PER_MSEC; +- bw = (u64)delivered * BW_UNIT; +- do_div(bw, t); +- bbr_lt_bw_interval_done(sk, bw); +-} +- +-/* Estimate the bandwidth based on how fast packets are delivered */ +-static void bbr_update_bw(struct sock *sk, const struct rate_sample *rs) +-{ +- struct tcp_sock *tp = tcp_sk(sk); +- struct bbr *bbr = inet_csk_ca(sk); +- u64 bw; ++ u32 round_delivered = 0; + + bbr->round_start = 0; +- if (rs->delivered < 0 || rs->interval_us <= 0) +- return; /* Not a valid observation */ + + /* See if we've reached the next RTT */ +- if (!before(rs->prior_delivered, bbr->next_rtt_delivered)) { ++ if (rs->interval_us > 0 && ++ !before(rs->prior_delivered, bbr->next_rtt_delivered)) { ++ round_delivered = tp->delivered - bbr->next_rtt_delivered; + bbr->next_rtt_delivered = tp->delivered; +- bbr->rtt_cnt++; + bbr->round_start = 1; +- bbr->packet_conservation = 0; + } ++ return round_delivered; ++} + +- bbr_lt_bw_sampling(sk, rs); ++/* Calculate the bandwidth based on how fast packets are delivered */ ++static void bbr_calculate_bw_sample(struct sock *sk, ++ const struct rate_sample *rs, struct bbr_context *ctx) ++{ ++ u64 bw = 0; + + /* Divide delivered by the interval to find a (lower bound) bottleneck + * bandwidth sample. Delivered is in packets and interval_us in uS and + * ratio will be <<1 for most connections. So delivered is first scaled. ++ * Round up to allow growth at low rates, even with integer division. + */ +- bw = div64_long((u64)rs->delivered * BW_UNIT, rs->interval_us); ++ if (rs->interval_us > 0) { ++ if (WARN_ONCE(rs->delivered < 0, ++ "negative delivered: %d interval_us: %ld\n", ++ rs->delivered, rs->interval_us)) ++ return; + +- /* If this sample is application-limited, it is likely to have a very +- * low delivered count that represents application behavior rather than +- * the available network rate. Such a sample could drag down estimated +- * bw, causing needless slow-down. Thus, to continue to send at the +- * last measured network rate, we filter out app-limited samples unless +- * they describe the path bw at least as well as our bw model. +- * +- * So the goal during app-limited phase is to proceed with the best +- * network rate no matter how long. We automatically leave this +- * phase when app writes faster than the network can deliver :) +- */ +- if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) { +- /* Incorporate new sample into our max bw filter. */ +- minmax_running_max(&bbr->bw, bbr_bw_rtts, bbr->rtt_cnt, bw); ++ bw = DIV_ROUND_UP_ULL((u64)rs->delivered * BW_UNIT, rs->interval_us); + } ++ ++ ctx->sample_bw = bw; + } + + /* Estimates the windowed max degree of ack aggregation. +@@ -826,7 +794,7 @@ static void bbr_update_bw(struct sock *s + * + * Max extra_acked is clamped by cwnd and bw * bbr_extra_acked_max_us (100 ms). + * Max filter is an approximate sliding window of 5-10 (packet timed) round +- * trips. ++ * trips for non-startup phase, and 1-2 round trips for startup. + */ + static void bbr_update_ack_aggregation(struct sock *sk, + const struct rate_sample *rs) +@@ -834,15 +802,19 @@ static void bbr_update_ack_aggregation(s + u32 epoch_us, expected_acked, extra_acked; + struct bbr *bbr = inet_csk_ca(sk); + struct tcp_sock *tp = tcp_sk(sk); ++ u32 extra_acked_win_rtts_thresh = bbr_param(sk, extra_acked_win_rtts); + +- if (!bbr_extra_acked_gain || rs->acked_sacked <= 0 || ++ if (!bbr_param(sk, extra_acked_gain) || rs->acked_sacked <= 0 || + rs->delivered < 0 || rs->interval_us <= 0) + return; + + if (bbr->round_start) { + bbr->extra_acked_win_rtts = min(0x1F, + bbr->extra_acked_win_rtts + 1); +- if (bbr->extra_acked_win_rtts >= bbr_extra_acked_win_rtts) { ++ if (!bbr_full_bw_reached(sk)) ++ extra_acked_win_rtts_thresh = 1; ++ if (bbr->extra_acked_win_rtts >= ++ extra_acked_win_rtts_thresh) { + bbr->extra_acked_win_rtts = 0; + bbr->extra_acked_win_idx = bbr->extra_acked_win_idx ? + 0 : 1; +@@ -876,49 +848,6 @@ static void bbr_update_ack_aggregation(s + bbr->extra_acked[bbr->extra_acked_win_idx] = extra_acked; + } + +-/* Estimate when the pipe is full, using the change in delivery rate: BBR +- * estimates that STARTUP filled the pipe if the estimated bw hasn't changed by +- * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited +- * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the +- * higher rwin, 3: we get higher delivery rate samples. Or transient +- * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar +- * design goal, but uses delay and inter-ACK spacing instead of bandwidth. +- */ +-static void bbr_check_full_bw_reached(struct sock *sk, +- const struct rate_sample *rs) +-{ +- struct bbr *bbr = inet_csk_ca(sk); +- u32 bw_thresh; +- +- if (bbr_full_bw_reached(sk) || !bbr->round_start || rs->is_app_limited) +- return; +- +- bw_thresh = (u64)bbr->full_bw * bbr_full_bw_thresh >> BBR_SCALE; +- if (bbr_max_bw(sk) >= bw_thresh) { +- bbr->full_bw = bbr_max_bw(sk); +- bbr->full_bw_cnt = 0; +- return; +- } +- ++bbr->full_bw_cnt; +- bbr->full_bw_reached = bbr->full_bw_cnt >= bbr_full_bw_cnt; +-} +- +-/* If pipe is probably full, drain the queue and then enter steady-state. */ +-static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs) +-{ +- struct bbr *bbr = inet_csk_ca(sk); +- +- if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) { +- bbr->mode = BBR_DRAIN; /* drain queue we created */ +- tcp_sk(sk)->snd_ssthresh = +- bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); +- } /* fall through to check if in-flight is already small: */ +- if (bbr->mode == BBR_DRAIN && +- bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <= +- bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) +- bbr_reset_probe_bw_mode(sk); /* we estimate queue is drained */ +-} +- + static void bbr_check_probe_rtt_done(struct sock *sk) + { + struct tcp_sock *tp = tcp_sk(sk); +@@ -928,9 +857,9 @@ static void bbr_check_probe_rtt_done(str + after(tcp_jiffies32, bbr->probe_rtt_done_stamp))) + return; + +- bbr->min_rtt_stamp = tcp_jiffies32; /* wait a while until PROBE_RTT */ ++ bbr->probe_rtt_min_stamp = tcp_jiffies32; /* schedule next PROBE_RTT */ + tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd)); +- bbr_reset_mode(sk); ++ bbr_exit_probe_rtt(sk); + } + + /* The goal of PROBE_RTT mode is to have BBR flows cooperatively and +@@ -956,23 +885,35 @@ static void bbr_update_min_rtt(struct so + { + struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); +- bool filter_expired; ++ bool probe_rtt_expired, min_rtt_expired; ++ u32 expire; + +- /* Track min RTT seen in the min_rtt_win_sec filter window: */ +- filter_expired = after(tcp_jiffies32, +- bbr->min_rtt_stamp + bbr_min_rtt_win_sec * HZ); ++ /* Track min RTT in probe_rtt_win_ms to time next PROBE_RTT state. */ ++ expire = bbr->probe_rtt_min_stamp + ++ msecs_to_jiffies(bbr_param(sk, probe_rtt_win_ms)); ++ probe_rtt_expired = after(tcp_jiffies32, expire); + if (rs->rtt_us >= 0 && +- (rs->rtt_us < bbr->min_rtt_us || +- (filter_expired && !rs->is_ack_delayed))) { +- bbr->min_rtt_us = rs->rtt_us; +- bbr->min_rtt_stamp = tcp_jiffies32; ++ (rs->rtt_us < bbr->probe_rtt_min_us || ++ (probe_rtt_expired && !rs->is_ack_delayed))) { ++ bbr->probe_rtt_min_us = rs->rtt_us; ++ bbr->probe_rtt_min_stamp = tcp_jiffies32; ++ } ++ /* Track min RTT seen in the min_rtt_win_sec filter window: */ ++ expire = bbr->min_rtt_stamp + bbr_param(sk, min_rtt_win_sec) * HZ; ++ min_rtt_expired = after(tcp_jiffies32, expire); ++ if (bbr->probe_rtt_min_us <= bbr->min_rtt_us || ++ min_rtt_expired) { ++ bbr->min_rtt_us = bbr->probe_rtt_min_us; ++ bbr->min_rtt_stamp = bbr->probe_rtt_min_stamp; + } + +- if (bbr_probe_rtt_mode_ms > 0 && filter_expired && ++ if (bbr_param(sk, probe_rtt_mode_ms) > 0 && probe_rtt_expired && + !bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) { + bbr->mode = BBR_PROBE_RTT; /* dip, drain queue */ + bbr_save_cwnd(sk); /* note cwnd so we can restore it */ + bbr->probe_rtt_done_stamp = 0; ++ bbr->ack_phase = BBR_ACKS_PROBE_STOPPING; ++ bbr->next_rtt_delivered = tp->delivered; + } + + if (bbr->mode == BBR_PROBE_RTT) { +@@ -981,9 +922,9 @@ static void bbr_update_min_rtt(struct so + (tp->delivered + tcp_packets_in_flight(tp)) ? : 1; + /* Maintain min packets in flight for max(200 ms, 1 round). */ + if (!bbr->probe_rtt_done_stamp && +- tcp_packets_in_flight(tp) <= bbr_cwnd_min_target) { ++ tcp_packets_in_flight(tp) <= bbr_probe_rtt_cwnd(sk)) { + bbr->probe_rtt_done_stamp = tcp_jiffies32 + +- msecs_to_jiffies(bbr_probe_rtt_mode_ms); ++ msecs_to_jiffies(bbr_param(sk, probe_rtt_mode_ms)); + bbr->probe_rtt_round_done = 0; + bbr->next_rtt_delivered = tp->delivered; + } else if (bbr->probe_rtt_done_stamp) { +@@ -1004,18 +945,20 @@ static void bbr_update_gains(struct sock + + switch (bbr->mode) { + case BBR_STARTUP: +- bbr->pacing_gain = bbr_high_gain; +- bbr->cwnd_gain = bbr_high_gain; ++ bbr->pacing_gain = bbr_param(sk, startup_pacing_gain); ++ bbr->cwnd_gain = bbr_param(sk, startup_cwnd_gain); + break; + case BBR_DRAIN: +- bbr->pacing_gain = bbr_drain_gain; /* slow, to drain */ +- bbr->cwnd_gain = bbr_high_gain; /* keep cwnd */ ++ bbr->pacing_gain = bbr_param(sk, drain_gain); /* slow, to drain */ ++ bbr->cwnd_gain = bbr_param(sk, startup_cwnd_gain); /* keep cwnd */ + break; + case BBR_PROBE_BW: +- bbr->pacing_gain = (bbr->lt_use_bw ? +- BBR_UNIT : +- bbr_pacing_gain[bbr->cycle_idx]); +- bbr->cwnd_gain = bbr_cwnd_gain; ++ bbr->pacing_gain = bbr_pacing_gain[bbr->cycle_idx]; ++ bbr->cwnd_gain = bbr_param(sk, cwnd_gain); ++ if (bbr_param(sk, bw_probe_cwnd_gain) && ++ bbr->cycle_idx == BBR_BW_PROBE_UP) ++ bbr->cwnd_gain += ++ BBR_UNIT * bbr_param(sk, bw_probe_cwnd_gain) / 4; + break; + case BBR_PROBE_RTT: + bbr->pacing_gain = BBR_UNIT; +@@ -1027,27 +970,1108 @@ static void bbr_update_gains(struct sock + } + } + +-static void bbr_update_model(struct sock *sk, const struct rate_sample *rs) ++__bpf_kfunc static u32 bbr_sndbuf_expand(struct sock *sk) ++{ ++ /* Provision 3 * cwnd since BBR may slow-start even during recovery. */ ++ return 3; ++} ++ ++/* Incorporate a new bw sample into the current window of our max filter. */ ++static void bbr_take_max_bw_sample(struct sock *sk, u32 bw) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr->bw_hi[1] = max(bw, bbr->bw_hi[1]); ++} ++ ++/* Keep max of last 1-2 cycles. Each PROBE_BW cycle, flip filter window. */ ++static void bbr_advance_max_bw_filter(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ if (!bbr->bw_hi[1]) ++ return; /* no samples in this window; remember old window */ ++ bbr->bw_hi[0] = bbr->bw_hi[1]; ++ bbr->bw_hi[1] = 0; ++} ++ ++/* Reset the estimator for reaching full bandwidth based on bw plateau. */ ++static void bbr_reset_full_bw(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr->full_bw = 0; ++ bbr->full_bw_cnt = 0; ++ bbr->full_bw_now = 0; ++} ++ ++/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */ ++static u32 bbr_target_inflight(struct sock *sk) ++{ ++ u32 bdp = bbr_inflight(sk, bbr_bw(sk), BBR_UNIT); ++ ++ return min(bdp, tcp_sk(sk)->snd_cwnd); ++} ++ ++static bool bbr_is_probing_bandwidth(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ return (bbr->mode == BBR_STARTUP) || ++ (bbr->mode == BBR_PROBE_BW && ++ (bbr->cycle_idx == BBR_BW_PROBE_REFILL || ++ bbr->cycle_idx == BBR_BW_PROBE_UP)); ++} ++ ++/* Has the given amount of time elapsed since we marked the phase start? */ ++static bool bbr_has_elapsed_in_phase(const struct sock *sk, u32 interval_us) ++{ ++ const struct tcp_sock *tp = tcp_sk(sk); ++ const struct bbr *bbr = inet_csk_ca(sk); ++ ++ return tcp_stamp_us_delta(tp->tcp_mstamp, ++ bbr->cycle_mstamp + interval_us) > 0; ++} ++ ++static void bbr_handle_queue_too_high_in_startup(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 bdp; /* estimated BDP in packets, with quantization budget */ ++ ++ bbr->full_bw_reached = 1; ++ ++ bdp = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); ++ bbr->inflight_hi = max(bdp, bbr->inflight_latest); ++} ++ ++/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */ ++static void bbr_check_ecn_too_high_in_startup(struct sock *sk, u32 ce_ratio) + { +- bbr_update_bw(sk, rs); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ if (bbr_full_bw_reached(sk) || !bbr->ecn_eligible || ++ !bbr_param(sk, full_ecn_cnt) || !bbr_param(sk, ecn_thresh)) ++ return; ++ ++ if (ce_ratio >= bbr_param(sk, ecn_thresh)) ++ bbr->startup_ecn_rounds++; ++ else ++ bbr->startup_ecn_rounds = 0; ++ ++ if (bbr->startup_ecn_rounds >= bbr_param(sk, full_ecn_cnt)) { ++ bbr_handle_queue_too_high_in_startup(sk); ++ return; ++ } ++} ++ ++/* Updates ecn_alpha and returns ce_ratio. -1 if not available. */ ++static int bbr_update_ecn_alpha(struct sock *sk) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct net *net = sock_net(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ s32 delivered, delivered_ce; ++ u64 alpha, ce_ratio; ++ u32 gain; ++ bool want_ecn_alpha; ++ ++ /* See if we should use ECN sender logic for this connection. */ ++ if (!bbr->ecn_eligible && bbr_can_use_ecn(sk) && ++ bbr_param(sk, ecn_factor) && ++ (bbr->min_rtt_us <= bbr_ecn_max_rtt_us || ++ !bbr_ecn_max_rtt_us)) ++ bbr->ecn_eligible = 1; ++ ++ /* Skip updating alpha only if not ECN-eligible and PLB is disabled. */ ++ want_ecn_alpha = (bbr->ecn_eligible || ++ (bbr_can_use_ecn(sk) && ++ READ_ONCE(net->ipv4.sysctl_tcp_plb_enabled))); ++ if (!want_ecn_alpha) ++ return -1; ++ ++ delivered = tp->delivered - bbr->alpha_last_delivered; ++ delivered_ce = tp->delivered_ce - bbr->alpha_last_delivered_ce; ++ ++ if (delivered == 0 || /* avoid divide by zero */ ++ WARN_ON_ONCE(delivered < 0 || delivered_ce < 0)) /* backwards? */ ++ return -1; ++ ++ BUILD_BUG_ON(BBR_SCALE != TCP_PLB_SCALE); ++ ce_ratio = (u64)delivered_ce << BBR_SCALE; ++ do_div(ce_ratio, delivered); ++ ++ gain = bbr_param(sk, ecn_alpha_gain); ++ alpha = ((BBR_UNIT - gain) * bbr->ecn_alpha) >> BBR_SCALE; ++ alpha += (gain * ce_ratio) >> BBR_SCALE; ++ bbr->ecn_alpha = min_t(u32, alpha, BBR_UNIT); ++ ++ bbr->alpha_last_delivered = tp->delivered; ++ bbr->alpha_last_delivered_ce = tp->delivered_ce; ++ ++ bbr_check_ecn_too_high_in_startup(sk, ce_ratio); ++ return (int)ce_ratio; ++} ++ ++/* Protective Load Balancing (PLB). PLB rehashes outgoing data (to a new IPv6 ++ * flow label) if it encounters sustained congestion in the form of ECN marks. ++ */ ++static void bbr_plb(struct sock *sk, const struct rate_sample *rs, int ce_ratio) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ if (bbr->round_start && ce_ratio >= 0) ++ tcp_plb_update_state(sk, &bbr->plb, ce_ratio); ++ ++ tcp_plb_check_rehash(sk, &bbr->plb); ++} ++ ++/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */ ++static void bbr_raise_inflight_hi_slope(struct sock *sk) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 growth_this_round, cnt; ++ ++ /* Calculate "slope": packets S/Acked per inflight_hi increment. */ ++ growth_this_round = 1 << bbr->bw_probe_up_rounds; ++ bbr->bw_probe_up_rounds = min(bbr->bw_probe_up_rounds + 1, 30); ++ cnt = tcp_snd_cwnd(tp) / growth_this_round; ++ cnt = max(cnt, 1U); ++ bbr->bw_probe_up_cnt = cnt; ++} ++ ++/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */ ++static void bbr_probe_inflight_hi_upward(struct sock *sk, ++ const struct rate_sample *rs) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 delta; ++ ++ if (!tp->is_cwnd_limited || tcp_snd_cwnd(tp) < bbr->inflight_hi) ++ return; /* not fully using inflight_hi, so don't grow it */ ++ ++ /* For each bw_probe_up_cnt packets ACKed, increase inflight_hi by 1. */ ++ bbr->bw_probe_up_acks += rs->acked_sacked; ++ if (bbr->bw_probe_up_acks >= bbr->bw_probe_up_cnt) { ++ delta = bbr->bw_probe_up_acks / bbr->bw_probe_up_cnt; ++ bbr->bw_probe_up_acks -= delta * bbr->bw_probe_up_cnt; ++ bbr->inflight_hi += delta; ++ bbr->try_fast_path = 0; /* Need to update cwnd */ ++ } ++ ++ if (bbr->round_start) ++ bbr_raise_inflight_hi_slope(sk); ++} ++ ++/* Does loss/ECN rate for this sample say inflight is "too high"? ++ * This is used by both the bbr_check_loss_too_high_in_startup() function, ++ * 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 bbr_is_inflight_too_high(const struct sock *sk, ++ const struct rate_sample *rs) ++{ ++ const struct bbr *bbr = inet_csk_ca(sk); ++ u32 loss_thresh, ecn_thresh; ++ ++ if (rs->lost > 0 && rs->tx_in_flight) { ++ loss_thresh = (u64)rs->tx_in_flight * bbr_param(sk, loss_thresh) >> ++ BBR_SCALE; ++ if (rs->lost > loss_thresh) { ++ return true; ++ } ++ } ++ ++ if (rs->delivered_ce > 0 && rs->delivered > 0 && ++ bbr->ecn_eligible && bbr_param(sk, ecn_thresh)) { ++ ecn_thresh = (u64)rs->delivered * bbr_param(sk, ecn_thresh) >> ++ BBR_SCALE; ++ if (rs->delivered_ce > ecn_thresh) { ++ return true; ++ } ++ } ++ ++ return false; ++} ++ ++/* Calculate the tx_in_flight level that corresponded to excessive loss. ++ * We find "lost_prefix" segs of the skb where loss rate went too high, ++ * by solving for "lost_prefix" in the following equation: ++ * lost / inflight >= loss_thresh ++ * (lost_prev + lost_prefix) / (inflight_prev + lost_prefix) >= loss_thresh ++ * Then we take that equation, convert it to fixed point, and ++ * round up to the nearest packet. ++ */ ++static u32 bbr_inflight_hi_from_lost_skb(const struct sock *sk, ++ const struct rate_sample *rs, ++ const struct sk_buff *skb) ++{ ++ const struct tcp_sock *tp = tcp_sk(sk); ++ u32 loss_thresh = bbr_param(sk, loss_thresh); ++ u32 pcount, divisor, inflight_hi; ++ s32 inflight_prev, lost_prev; ++ u64 loss_budget, lost_prefix; ++ ++ pcount = tcp_skb_pcount(skb); ++ ++ /* How much data was in flight before this skb? */ ++ inflight_prev = rs->tx_in_flight - pcount; ++ if (inflight_prev < 0) { ++ WARN_ONCE(tcp_skb_tx_in_flight_is_suspicious( ++ pcount, ++ TCP_SKB_CB(skb)->sacked, ++ rs->tx_in_flight), ++ "tx_in_flight: %u pcount: %u reneg: %u", ++ rs->tx_in_flight, pcount, tcp_sk(sk)->is_sack_reneg); ++ return ~0U; ++ } ++ ++ /* How much inflight data was marked lost before this skb? */ ++ lost_prev = rs->lost - pcount; ++ if (WARN_ONCE(lost_prev < 0, ++ "cwnd: %u ca: %d out: %u lost: %u pif: %u " ++ "tx_in_flight: %u tx.lost: %u tp->lost: %u rs->lost: %d " ++ "lost_prev: %d pcount: %d seq: %u end_seq: %u reneg: %u", ++ tcp_snd_cwnd(tp), inet_csk(sk)->icsk_ca_state, ++ tp->packets_out, tp->lost_out, tcp_packets_in_flight(tp), ++ rs->tx_in_flight, TCP_SKB_CB(skb)->tx.lost, tp->lost, ++ rs->lost, lost_prev, pcount, ++ TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq, ++ tp->is_sack_reneg)) ++ return ~0U; ++ ++ /* At what prefix of this lost skb did losss rate exceed loss_thresh? */ ++ loss_budget = (u64)inflight_prev * loss_thresh + BBR_UNIT - 1; ++ loss_budget >>= BBR_SCALE; ++ if (lost_prev >= loss_budget) { ++ lost_prefix = 0; /* previous losses crossed loss_thresh */ ++ } else { ++ lost_prefix = loss_budget - lost_prev; ++ lost_prefix <<= BBR_SCALE; ++ divisor = BBR_UNIT - loss_thresh; ++ if (WARN_ON_ONCE(!divisor)) /* loss_thresh is 8 bits */ ++ return ~0U; ++ do_div(lost_prefix, divisor); ++ } ++ ++ inflight_hi = inflight_prev + lost_prefix; ++ return inflight_hi; ++} ++ ++/* If loss/ECN rates during probing indicated we may have overfilled a ++ * buffer, return an operating point that tries to leave unutilized headroom in ++ * the path for other flows, for fairness convergence and lower RTTs and loss. ++ */ ++static u32 bbr_inflight_with_headroom(const struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 headroom, headroom_fraction; ++ ++ if (bbr->inflight_hi == ~0U) ++ return ~0U; ++ ++ headroom_fraction = bbr_param(sk, inflight_headroom); ++ headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE; ++ headroom = max(headroom, 1U); ++ return max_t(s32, bbr->inflight_hi - headroom, ++ bbr_param(sk, cwnd_min_target)); ++} ++ ++/* Bound cwnd to a sensible level, based on our current probing state ++ * machine phase and model of a good inflight level (inflight_lo, inflight_hi). ++ */ ++static void bbr_bound_cwnd_for_inflight_model(struct sock *sk) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 cap; ++ ++ /* tcp_rcv_synsent_state_process() currently calls tcp_ack() ++ * and thus cong_control() without first initializing us(!). ++ */ ++ if (!bbr->initialized) ++ return; ++ ++ cap = ~0U; ++ if (bbr->mode == BBR_PROBE_BW && ++ bbr->cycle_idx != BBR_BW_PROBE_CRUISE) { ++ /* Probe to see if more packets fit in the path. */ ++ cap = bbr->inflight_hi; ++ } else { ++ if (bbr->mode == BBR_PROBE_RTT || ++ (bbr->mode == BBR_PROBE_BW && ++ bbr->cycle_idx == BBR_BW_PROBE_CRUISE)) ++ cap = bbr_inflight_with_headroom(sk); ++ } ++ /* Adapt to any loss/ECN since our last bw probe. */ ++ cap = min(cap, bbr->inflight_lo); ++ ++ cap = max_t(u32, cap, bbr_param(sk, cwnd_min_target)); ++ tcp_snd_cwnd_set(tp, min(cap, tcp_snd_cwnd(tp))); ++} ++ ++/* How should we multiplicatively cut bw or inflight limits based on ECN? */ ++u32 bbr_ecn_cut(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ return BBR_UNIT - ++ ((bbr->ecn_alpha * bbr_param(sk, ecn_factor)) >> BBR_SCALE); ++} ++ ++/* Init lower bounds if have not inited yet. */ ++static void bbr_init_lower_bounds(struct sock *sk, bool init_bw) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ if (init_bw && bbr->bw_lo == ~0U) ++ bbr->bw_lo = bbr_max_bw(sk); ++ if (bbr->inflight_lo == ~0U) ++ bbr->inflight_lo = tcp_snd_cwnd(tp); ++} ++ ++/* Reduce bw and inflight to (1 - beta). */ ++static void bbr_loss_lower_bounds(struct sock *sk, u32 *bw, u32 *inflight) ++{ ++ struct bbr* bbr = inet_csk_ca(sk); ++ u32 loss_cut = BBR_UNIT - bbr_param(sk, beta); ++ ++ *bw = max_t(u32, bbr->bw_latest, ++ (u64)bbr->bw_lo * loss_cut >> BBR_SCALE); ++ *inflight = max_t(u32, bbr->inflight_latest, ++ (u64)bbr->inflight_lo * loss_cut >> BBR_SCALE); ++} ++ ++/* Reduce inflight to (1 - alpha*ecn_factor). */ ++static void bbr_ecn_lower_bounds(struct sock *sk, u32 *inflight) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 ecn_cut = bbr_ecn_cut(sk); ++ ++ *inflight = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE; ++} ++ ++/* Estimate a short-term lower bound on the capacity available now, based ++ * on measurements of the current delivery process and recent history. When we ++ * are seeing loss/ECN at times when we are not probing bw, then conservatively ++ * move toward flow balance by multiplicatively cutting our short-term ++ * estimated safe rate and volume of data (bw_lo and inflight_lo). We use a ++ * multiplicative decrease in order to converge to a lower capacity in time ++ * logarithmic in the magnitude of the decrease. ++ * ++ * However, we do not cut our short-term estimates lower than the current rate ++ * and volume of delivered data from this round trip, since from the current ++ * delivery process we can estimate the measured capacity available now. ++ * ++ * Anything faster than that approach would knowingly risk high loss, which can ++ * cause low bw for Reno/CUBIC and high loss recovery latency for ++ * request/response flows using any congestion control. ++ */ ++static void bbr_adapt_lower_bounds(struct sock *sk, ++ const struct rate_sample *rs) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 ecn_inflight_lo = ~0U; ++ ++ /* We only use lower-bound estimates when not probing bw. ++ * When probing we need to push inflight higher to probe bw. ++ */ ++ if (bbr_is_probing_bandwidth(sk)) ++ return; ++ ++ /* ECN response. */ ++ if (bbr->ecn_in_round && bbr_param(sk, ecn_factor)) { ++ bbr_init_lower_bounds(sk, false); ++ bbr_ecn_lower_bounds(sk, &ecn_inflight_lo); ++ } ++ ++ /* Loss response. */ ++ if (bbr->loss_in_round) { ++ bbr_init_lower_bounds(sk, true); ++ bbr_loss_lower_bounds(sk, &bbr->bw_lo, &bbr->inflight_lo); ++ } ++ ++ /* Adjust to the lower of the levels implied by loss/ECN. */ ++ bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo); ++ bbr->bw_lo = max(1U, bbr->bw_lo); ++} ++ ++/* Reset any short-term lower-bound adaptation to congestion, so that we can ++ * push our inflight up. ++ */ ++static void bbr_reset_lower_bounds(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr->bw_lo = ~0U; ++ bbr->inflight_lo = ~0U; ++} ++ ++/* After bw probing (STARTUP/PROBE_UP), reset signals before entering a state ++ * machine phase where we adapt our lower bound based on congestion signals. ++ */ ++static void bbr_reset_congestion_signals(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr->loss_in_round = 0; ++ bbr->ecn_in_round = 0; ++ bbr->loss_in_cycle = 0; ++ bbr->ecn_in_cycle = 0; ++ bbr->bw_latest = 0; ++ bbr->inflight_latest = 0; ++} ++ ++static void bbr_exit_loss_recovery(struct sock *sk) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd)); ++ bbr->try_fast_path = 0; /* bound cwnd using latest model */ ++} ++ ++/* Update rate and volume of delivered data from latest round trip. */ ++static void bbr_update_latest_delivery_signals( ++ struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr->loss_round_start = 0; ++ if (rs->interval_us <= 0 || !rs->acked_sacked) ++ return; /* Not a valid observation */ ++ ++ bbr->bw_latest = max_t(u32, bbr->bw_latest, ctx->sample_bw); ++ bbr->inflight_latest = max_t(u32, bbr->inflight_latest, rs->delivered); ++ ++ if (!before(rs->prior_delivered, bbr->loss_round_delivered)) { ++ bbr->loss_round_delivered = tp->delivered; ++ bbr->loss_round_start = 1; /* mark start of new round trip */ ++ } ++} ++ ++/* Once per round, reset filter for latest rate and volume of delivered data. */ ++static void bbr_advance_latest_delivery_signals( ++ struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ /* If ACK matches a TLP retransmit, persist the filter. If we detect ++ * that a TLP retransmit plugged a tail loss, we'll want to remember ++ * how much data the path delivered before the tail loss. ++ */ ++ if (bbr->loss_round_start && !rs->is_acking_tlp_retrans_seq) { ++ bbr->bw_latest = ctx->sample_bw; ++ bbr->inflight_latest = rs->delivered; ++ } ++} ++ ++/* Update (most of) our congestion signals: track the recent rate and volume of ++ * delivered data, presence of loss, and EWMA degree of ECN marking. ++ */ ++static void bbr_update_congestion_signals( ++ struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u64 bw; ++ ++ if (rs->interval_us <= 0 || !rs->acked_sacked) ++ return; /* Not a valid observation */ ++ bw = ctx->sample_bw; ++ ++ if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) ++ bbr_take_max_bw_sample(sk, bw); ++ ++ bbr->loss_in_round |= (rs->losses > 0); ++ ++ if (!bbr->loss_round_start) ++ return; /* skip the per-round-trip updates */ ++ /* Now do per-round-trip updates. */ ++ bbr_adapt_lower_bounds(sk, rs); ++ ++ bbr->loss_in_round = 0; ++ bbr->ecn_in_round = 0; ++} ++ ++/* Bandwidth probing can cause loss. To help coexistence with loss-based ++ * congestion control we spread out our probing in a Reno-conscious way. Due to ++ * the shape of the Reno sawtooth, the time required between loss epochs for an ++ * idealized Reno flow is a number of round trips that is the BDP of that ++ * flow. We count packet-timed round trips directly, since measured RTT can ++ * vary widely, and Reno is driven by packet-timed round trips. ++ */ ++static bool bbr_is_reno_coexistence_probe_time(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 rounds; ++ ++ /* Random loss can shave some small percentage off of our inflight ++ * in each round. To survive this, flows need robust periodic probes. ++ */ ++ rounds = min_t(u32, bbr_param(sk, bw_probe_max_rounds), bbr_target_inflight(sk)); ++ return bbr->rounds_since_probe >= rounds; ++} ++ ++/* How long do we want to wait before probing for bandwidth (and risking ++ * loss)? We randomize the wait, for better mixing and fairness convergence. ++ * ++ * We bound the Reno-coexistence inter-bw-probe time to be 62-63 round trips. ++ * This is calculated to allow fairness with a 25Mbps, 30ms Reno flow, ++ * (eg 4K video to a broadband user): ++ * BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets ++ * ++ * We bound the BBR-native inter-bw-probe wall clock time to be: ++ * (a) higher than 2 sec: to try to avoid causing loss for a long enough time ++ * to allow Reno at 30ms to get 4K video bw, the inter-bw-probe time must ++ * be at least: 25Mbps * .030sec / (1514bytes) * 0.030sec = 1.9secs ++ * (b) lower than 3 sec: to ensure flows can start probing in a reasonable ++ * amount of time to discover unutilized bw on human-scale interactive ++ * time-scales (e.g. perhaps traffic from a web page download that we ++ * were competing with is now complete). ++ */ ++static void bbr_pick_probe_wait(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ /* Decide the random round-trip bound for wait until probe: */ ++ bbr->rounds_since_probe = ++ get_random_u32_below(bbr_param(sk, bw_probe_rand_rounds)); ++ /* Decide the random wall clock bound for wait until probe: */ ++ bbr->probe_wait_us = bbr_param(sk, bw_probe_base_us) + ++ get_random_u32_below(bbr_param(sk, bw_probe_rand_us)); ++} ++ ++static void bbr_set_cycle_idx(struct sock *sk, int cycle_idx) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr->cycle_idx = cycle_idx; ++ /* New phase, so need to update cwnd and pacing rate. */ ++ bbr->try_fast_path = 0; ++} ++ ++/* Send at estimated bw to fill the pipe, but not queue. We need this phase ++ * before PROBE_UP, because as soon as we send faster than the available bw ++ * we will start building a queue, and if the buffer is shallow we can cause ++ * loss. If we do not fill the pipe before we cause this loss, our bw_hi and ++ * inflight_hi estimates will underestimate. ++ */ ++static void bbr_start_bw_probe_refill(struct sock *sk, u32 bw_probe_up_rounds) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr_reset_lower_bounds(sk); ++ bbr->bw_probe_up_rounds = bw_probe_up_rounds; ++ bbr->bw_probe_up_acks = 0; ++ bbr->stopped_risky_probe = 0; ++ bbr->ack_phase = BBR_ACKS_REFILLING; ++ bbr->next_rtt_delivered = tp->delivered; ++ bbr_set_cycle_idx(sk, BBR_BW_PROBE_REFILL); ++} ++ ++/* Now probe max deliverable data rate and volume. */ ++static void bbr_start_bw_probe_up(struct sock *sk, struct bbr_context *ctx) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr->ack_phase = BBR_ACKS_PROBE_STARTING; ++ bbr->next_rtt_delivered = tp->delivered; ++ bbr->cycle_mstamp = tp->tcp_mstamp; ++ bbr_reset_full_bw(sk); ++ bbr->full_bw = ctx->sample_bw; ++ bbr_set_cycle_idx(sk, BBR_BW_PROBE_UP); ++ bbr_raise_inflight_hi_slope(sk); ++} ++ ++/* Start a new PROBE_BW probing cycle of some wall clock length. Pick a wall ++ * clock time at which to probe beyond an inflight that we think to be ++ * safe. This will knowingly risk packet loss, so we want to do this rarely, to ++ * keep packet loss rates low. Also start a round-trip counter, to probe faster ++ * if we estimate a Reno flow at our BDP would probe faster. ++ */ ++static void bbr_start_bw_probe_down(struct sock *sk) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr_reset_congestion_signals(sk); ++ bbr->bw_probe_up_cnt = ~0U; /* not growing inflight_hi any more */ ++ bbr_pick_probe_wait(sk); ++ bbr->cycle_mstamp = tp->tcp_mstamp; /* start wall clock */ ++ bbr->ack_phase = BBR_ACKS_PROBE_STOPPING; ++ bbr->next_rtt_delivered = tp->delivered; ++ bbr_set_cycle_idx(sk, BBR_BW_PROBE_DOWN); ++} ++ ++/* Cruise: maintain what we estimate to be a neutral, conservative ++ * operating point, without attempting to probe up for bandwidth or down for ++ * RTT, and only reducing inflight in response to loss/ECN signals. ++ */ ++static void bbr_start_bw_probe_cruise(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ if (bbr->inflight_lo != ~0U) ++ bbr->inflight_lo = min(bbr->inflight_lo, bbr->inflight_hi); ++ ++ bbr_set_cycle_idx(sk, BBR_BW_PROBE_CRUISE); ++} ++ ++/* Loss and/or ECN rate is too high while probing. ++ * Adapt (once per bw probe) by cutting inflight_hi and then restarting cycle. ++ */ ++static void bbr_handle_inflight_too_high(struct sock *sk, ++ const struct rate_sample *rs) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ const u32 beta = bbr_param(sk, beta); ++ ++ bbr->prev_probe_too_high = 1; ++ bbr->bw_probe_samples = 0; /* only react once per probe */ ++ /* If we are app-limited then we are not robustly ++ * probing the max volume of inflight data we think ++ * might be safe (analogous to how app-limited bw ++ * samples are not known to be robustly probing bw). ++ */ ++ if (!rs->is_app_limited) { ++ bbr->inflight_hi = max_t(u32, rs->tx_in_flight, ++ (u64)bbr_target_inflight(sk) * ++ (BBR_UNIT - beta) >> BBR_SCALE); ++ } ++ if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) ++ bbr_start_bw_probe_down(sk); ++} ++ ++/* If we're seeing bw and loss samples reflecting our bw probing, adapt ++ * using the signals we see. If loss or ECN mark rate gets too high, then adapt ++ * inflight_hi downward. If we're able to push inflight higher without such ++ * signals, push higher: adapt inflight_hi upward. ++ */ ++static bool bbr_adapt_upper_bounds(struct sock *sk, ++ const struct rate_sample *rs, ++ struct bbr_context *ctx) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ /* Track when we'll see bw/loss samples resulting from our bw probes. */ ++ if (bbr->ack_phase == BBR_ACKS_PROBE_STARTING && bbr->round_start) ++ bbr->ack_phase = BBR_ACKS_PROBE_FEEDBACK; ++ if (bbr->ack_phase == BBR_ACKS_PROBE_STOPPING && bbr->round_start) { ++ /* End of samples from bw probing phase. */ ++ bbr->bw_probe_samples = 0; ++ bbr->ack_phase = BBR_ACKS_INIT; ++ /* At this point in the cycle, our current bw sample is also ++ * our best recent chance at finding the highest available bw ++ * for this flow. So now is the best time to forget the bw ++ * samples from the previous cycle, by advancing the window. ++ */ ++ if (bbr->mode == BBR_PROBE_BW && !rs->is_app_limited) ++ bbr_advance_max_bw_filter(sk); ++ /* If we had an inflight_hi, then probed and pushed inflight all ++ * the way up to hit that inflight_hi without seeing any ++ * high loss/ECN in all the resulting ACKs from that probing, ++ * then probe up again, this time letting inflight persist at ++ * inflight_hi for a round trip, then accelerating beyond. ++ */ ++ if (bbr->mode == BBR_PROBE_BW && ++ bbr->stopped_risky_probe && !bbr->prev_probe_too_high) { ++ bbr_start_bw_probe_refill(sk, 0); ++ return true; /* yes, decided state transition */ ++ } ++ } ++ if (bbr_is_inflight_too_high(sk, rs)) { ++ if (bbr->bw_probe_samples) /* sample is from bw probing? */ ++ bbr_handle_inflight_too_high(sk, rs); ++ } else { ++ /* Loss/ECN rate is declared safe. Adjust upper bound upward. */ ++ ++ if (bbr->inflight_hi == ~0U) ++ return false; /* no excess queue signals yet */ ++ ++ /* To be resilient to random loss, we must raise bw/inflight_hi ++ * if we observe in any phase that a higher level is safe. ++ */ ++ if (rs->tx_in_flight > bbr->inflight_hi) { ++ bbr->inflight_hi = rs->tx_in_flight; ++ } ++ ++ if (bbr->mode == BBR_PROBE_BW && ++ bbr->cycle_idx == BBR_BW_PROBE_UP) ++ bbr_probe_inflight_hi_upward(sk, rs); ++ } ++ ++ return false; ++} ++ ++/* Check if it's time to probe for bandwidth now, and if so, kick it off. */ ++static bool bbr_check_time_to_probe_bw(struct sock *sk, ++ const struct rate_sample *rs) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 n; ++ ++ /* If we seem to be at an operating point where we are not seeing loss ++ * but we are seeing ECN marks, then when the ECN marks cease we reprobe ++ * quickly (in case cross-traffic has ceased and freed up bw). ++ */ ++ if (bbr_param(sk, ecn_reprobe_gain) && bbr->ecn_eligible && ++ bbr->ecn_in_cycle && !bbr->loss_in_cycle && ++ inet_csk(sk)->icsk_ca_state == TCP_CA_Open) { ++ /* Calculate n so that when bbr_raise_inflight_hi_slope() ++ * computes growth_this_round as 2^n it will be roughly the ++ * desired volume of data (inflight_hi*ecn_reprobe_gain). ++ */ ++ n = ilog2((((u64)bbr->inflight_hi * ++ bbr_param(sk, ecn_reprobe_gain)) >> BBR_SCALE)); ++ bbr_start_bw_probe_refill(sk, n); ++ return true; ++ } ++ ++ if (bbr_has_elapsed_in_phase(sk, bbr->probe_wait_us) || ++ bbr_is_reno_coexistence_probe_time(sk)) { ++ bbr_start_bw_probe_refill(sk, 0); ++ return true; ++ } ++ return false; ++} ++ ++/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */ ++static bool bbr_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw) ++{ ++ /* Always need to pull inflight down to leave headroom in queue. */ ++ if (inflight > bbr_inflight_with_headroom(sk)) ++ return false; ++ ++ return inflight <= bbr_inflight(sk, bw, BBR_UNIT); ++} ++ ++/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */ ++static void bbr_update_cycle_phase(struct sock *sk, ++ const struct rate_sample *rs, ++ struct bbr_context *ctx) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ bool is_bw_probe_done = false; ++ u32 inflight, bw; ++ ++ if (!bbr_full_bw_reached(sk)) ++ return; ++ ++ /* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */ ++ if (bbr_adapt_upper_bounds(sk, rs, ctx)) ++ return; /* already decided state transition */ ++ ++ if (bbr->mode != BBR_PROBE_BW) ++ return; ++ ++ inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight); ++ bw = bbr_max_bw(sk); ++ ++ switch (bbr->cycle_idx) { ++ /* First we spend most of our time cruising with a pacing_gain of 1.0, ++ * which paces at the estimated bw, to try to fully use the pipe ++ * without building queue. If we encounter loss/ECN marks, we adapt ++ * by slowing down. ++ */ ++ case BBR_BW_PROBE_CRUISE: ++ if (bbr_check_time_to_probe_bw(sk, rs)) ++ return; /* already decided state transition */ ++ break; ++ ++ /* After cruising, when it's time to probe, we first "refill": we send ++ * at the estimated bw to fill the pipe, before probing higher and ++ * knowingly risking overflowing the bottleneck buffer (causing loss). ++ */ ++ case BBR_BW_PROBE_REFILL: ++ if (bbr->round_start) { ++ /* After one full round trip of sending in REFILL, we ++ * start to see bw samples reflecting our REFILL, which ++ * may be putting too much data in flight. ++ */ ++ bbr->bw_probe_samples = 1; ++ bbr_start_bw_probe_up(sk, ctx); ++ } ++ break; ++ ++ /* After we refill the pipe, we probe by using a pacing_gain > 1.0, to ++ * probe for bw. If we have not seen loss/ECN, we try to raise inflight ++ * to at least pacing_gain*BDP; note that this may take more than ++ * min_rtt if min_rtt is small (e.g. on a LAN). ++ * ++ * We terminate PROBE_UP bandwidth probing upon any of the following: ++ * ++ * (1) We've pushed inflight up to hit the inflight_hi target set in the ++ * most recent previous bw probe phase. Thus we want to start ++ * draining the queue immediately because it's very likely the most ++ * recently sent packets will fill the queue and cause drops. ++ * (2) If inflight_hi has not limited bandwidth growth recently, and ++ * yet delivered bandwidth has not increased much recently ++ * (bbr->full_bw_now). ++ * (3) Loss filter says loss rate is "too high". ++ * (4) ECN filter says ECN mark rate is "too high". ++ * ++ * (1) (2) checked here, (3) (4) checked in bbr_is_inflight_too_high() ++ */ ++ case BBR_BW_PROBE_UP: ++ if (bbr->prev_probe_too_high && ++ inflight >= bbr->inflight_hi) { ++ bbr->stopped_risky_probe = 1; ++ is_bw_probe_done = true; ++ } else { ++ if (tp->is_cwnd_limited && ++ tcp_snd_cwnd(tp) >= bbr->inflight_hi) { ++ /* inflight_hi is limiting bw growth */ ++ bbr_reset_full_bw(sk); ++ bbr->full_bw = ctx->sample_bw; ++ } else if (bbr->full_bw_now) { ++ /* Plateau in estimated bw. Pipe looks full. */ ++ is_bw_probe_done = true; ++ } ++ } ++ if (is_bw_probe_done) { ++ bbr->prev_probe_too_high = 0; /* no loss/ECN (yet) */ ++ bbr_start_bw_probe_down(sk); /* restart w/ down */ ++ } ++ break; ++ ++ /* After probing in PROBE_UP, we have usually accumulated some data in ++ * the bottleneck buffer (if bw probing didn't find more bw). We next ++ * enter PROBE_DOWN to try to drain any excess data from the queue. To ++ * do this, we use a pacing_gain < 1.0. We hold this pacing gain until ++ * our inflight is less then that target cruising point, which is the ++ * minimum of (a) the amount needed to leave headroom, and (b) the ++ * estimated BDP. Once inflight falls to match the target, we estimate ++ * the queue is drained; persisting would underutilize the pipe. ++ */ ++ case BBR_BW_PROBE_DOWN: ++ if (bbr_check_time_to_probe_bw(sk, rs)) ++ return; /* already decided state transition */ ++ if (bbr_check_time_to_cruise(sk, inflight, bw)) ++ bbr_start_bw_probe_cruise(sk); ++ break; ++ ++ default: ++ WARN_ONCE(1, "BBR invalid cycle index %u\n", bbr->cycle_idx); ++ } ++} ++ ++/* Exiting PROBE_RTT, so return to bandwidth probing in STARTUP or PROBE_BW. */ ++static void bbr_exit_probe_rtt(struct sock *sk) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ bbr_reset_lower_bounds(sk); ++ if (bbr_full_bw_reached(sk)) { ++ bbr->mode = BBR_PROBE_BW; ++ /* Raising inflight after PROBE_RTT may cause loss, so reset ++ * the PROBE_BW clock and schedule the next bandwidth probe for ++ * a friendly and randomized future point in time. ++ */ ++ bbr_start_bw_probe_down(sk); ++ /* Since we are exiting PROBE_RTT, we know inflight is ++ * below our estimated BDP, so it is reasonable to cruise. ++ */ ++ bbr_start_bw_probe_cruise(sk); ++ } else { ++ bbr->mode = BBR_STARTUP; ++ } ++} ++ ++/* Exit STARTUP based on loss rate > 1% and loss gaps in round >= N. Wait until ++ * the end of the round in recovery to get a good estimate of how many packets ++ * have been lost, and how many we need to drain with a low pacing rate. ++ */ ++static void bbr_check_loss_too_high_in_startup(struct sock *sk, ++ const struct rate_sample *rs) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ if (bbr_full_bw_reached(sk)) ++ return; ++ ++ /* For STARTUP exit, check the loss rate at the end of each round trip ++ * of Recovery episodes in STARTUP. We check the loss rate at the end ++ * of the round trip to filter out noisy/low loss and have a better ++ * sense of inflight (extent of loss), so we can drain more accurately. ++ */ ++ if (rs->losses && bbr->loss_events_in_round < 0xf) ++ bbr->loss_events_in_round++; /* update saturating counter */ ++ if (bbr_param(sk, full_loss_cnt) && bbr->loss_round_start && ++ inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery && ++ bbr->loss_events_in_round >= bbr_param(sk, full_loss_cnt) && ++ bbr_is_inflight_too_high(sk, rs)) { ++ bbr_handle_queue_too_high_in_startup(sk); ++ return; ++ } ++ if (bbr->loss_round_start) ++ bbr->loss_events_in_round = 0; ++} ++ ++/* Estimate when the pipe is full, using the change in delivery rate: BBR ++ * estimates bw probing filled the pipe if the estimated bw hasn't changed by ++ * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited ++ * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the ++ * higher rwin, 3: we get higher delivery rate samples. Or transient ++ * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar ++ * design goal, but uses delay and inter-ACK spacing instead of bandwidth. ++ */ ++static void bbr_check_full_bw_reached(struct sock *sk, ++ const struct rate_sample *rs, ++ struct bbr_context *ctx) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 bw_thresh, full_cnt, thresh; ++ ++ if (bbr->full_bw_now || rs->is_app_limited) ++ return; ++ ++ thresh = bbr_param(sk, full_bw_thresh); ++ full_cnt = bbr_param(sk, full_bw_cnt); ++ bw_thresh = (u64)bbr->full_bw * thresh >> BBR_SCALE; ++ if (ctx->sample_bw >= bw_thresh) { ++ bbr_reset_full_bw(sk); ++ bbr->full_bw = ctx->sample_bw; ++ return; ++ } ++ if (!bbr->round_start) ++ return; ++ ++bbr->full_bw_cnt; ++ bbr->full_bw_now = bbr->full_bw_cnt >= full_cnt; ++ bbr->full_bw_reached |= bbr->full_bw_now; ++} ++ ++/* If pipe is probably full, drain the queue and then enter steady-state. */ ++static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs, ++ struct bbr_context *ctx) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) { ++ bbr->mode = BBR_DRAIN; /* drain queue we created */ ++ /* Set ssthresh to export purely for monitoring, to signal ++ * completion of initial STARTUP by setting to a non- ++ * TCP_INFINITE_SSTHRESH value (ssthresh is not used by BBR). ++ */ ++ tcp_sk(sk)->snd_ssthresh = ++ bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); ++ bbr_reset_congestion_signals(sk); ++ } /* fall through to check if in-flight is already small: */ ++ if (bbr->mode == BBR_DRAIN && ++ bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <= ++ bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) { ++ bbr->mode = BBR_PROBE_BW; ++ bbr_start_bw_probe_down(sk); ++ } ++} ++ ++static void bbr_update_model(struct sock *sk, const struct rate_sample *rs, ++ struct bbr_context *ctx) ++{ ++ bbr_update_congestion_signals(sk, rs, ctx); + bbr_update_ack_aggregation(sk, rs); +- bbr_update_cycle_phase(sk, rs); +- bbr_check_full_bw_reached(sk, rs); +- bbr_check_drain(sk, rs); ++ bbr_check_loss_too_high_in_startup(sk, rs); ++ bbr_check_full_bw_reached(sk, rs, ctx); ++ bbr_check_drain(sk, rs, ctx); ++ bbr_update_cycle_phase(sk, rs, ctx); + bbr_update_min_rtt(sk, rs); +- bbr_update_gains(sk); + } + +-__bpf_kfunc static void bbr_main(struct sock *sk, const struct rate_sample *rs) ++/* Fast path for app-limited case. ++ * ++ * On each ack, we execute bbr state machine, which primarily consists of: ++ * 1) update model based on new rate sample, and ++ * 2) update control based on updated model or state change. ++ * ++ * There are certain workload/scenarios, e.g. app-limited case, where ++ * either we can skip updating model or we can skip update of both model ++ * as well as control. This provides signifcant softirq cpu savings for ++ * processing incoming acks. ++ * ++ * In case of app-limited, if there is no congestion (loss/ecn) and ++ * if observed bw sample is less than current estimated bw, then we can ++ * skip some of the computation in bbr state processing: ++ * ++ * - if there is no rtt/mode/phase change: In this case, since all the ++ * parameters of the network model are constant, we can skip model ++ * as well control update. ++ * ++ * - else we can skip rest of the model update. But we still need to ++ * update the control to account for the new rtt/mode/phase. ++ * ++ * Returns whether we can take fast path or not. ++ */ ++static bool bbr_run_fast_path(struct sock *sk, bool *update_model, ++ const struct rate_sample *rs, struct bbr_context *ctx) ++{ ++ struct bbr *bbr = inet_csk_ca(sk); ++ u32 prev_min_rtt_us, prev_mode; ++ ++ if (bbr_param(sk, fast_path) && bbr->try_fast_path && ++ rs->is_app_limited && ctx->sample_bw < bbr_max_bw(sk) && ++ !bbr->loss_in_round && !bbr->ecn_in_round ) { ++ prev_mode = bbr->mode; ++ prev_min_rtt_us = bbr->min_rtt_us; ++ bbr_check_drain(sk, rs, ctx); ++ bbr_update_cycle_phase(sk, rs, ctx); ++ bbr_update_min_rtt(sk, rs); ++ ++ if (bbr->mode == prev_mode && ++ bbr->min_rtt_us == prev_min_rtt_us && ++ bbr->try_fast_path) { ++ return true; ++ } ++ ++ /* Skip model update, but control still needs to be updated */ ++ *update_model = false; ++ } ++ return false; ++} ++ ++__bpf_kfunc void bbr_main(struct sock *sk, const struct rate_sample *rs) + { ++ struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); +- u32 bw; ++ struct bbr_context ctx = { 0 }; ++ bool update_model = true; ++ u32 bw, round_delivered; ++ int ce_ratio = -1; ++ ++ round_delivered = bbr_update_round_start(sk, rs, &ctx); ++ if (bbr->round_start) { ++ bbr->rounds_since_probe = ++ min_t(s32, bbr->rounds_since_probe + 1, 0xFF); ++ ce_ratio = bbr_update_ecn_alpha(sk); ++ } ++ bbr_plb(sk, rs, ce_ratio); ++ ++ bbr->ecn_in_round |= (bbr->ecn_eligible && rs->is_ece); ++ bbr_calculate_bw_sample(sk, rs, &ctx); ++ bbr_update_latest_delivery_signals(sk, rs, &ctx); + +- bbr_update_model(sk, rs); ++ if (bbr_run_fast_path(sk, &update_model, rs, &ctx)) ++ goto out; + ++ if (update_model) ++ bbr_update_model(sk, rs, &ctx); ++ ++ bbr_update_gains(sk); + bw = bbr_bw(sk); + bbr_set_pacing_rate(sk, bw, bbr->pacing_gain); +- bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain); ++ bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain, ++ tcp_snd_cwnd(tp), &ctx); ++ bbr_bound_cwnd_for_inflight_model(sk); ++ ++out: ++ bbr_advance_latest_delivery_signals(sk, rs, &ctx); ++ bbr->prev_ca_state = inet_csk(sk)->icsk_ca_state; ++ bbr->loss_in_cycle |= rs->lost > 0; ++ bbr->ecn_in_cycle |= rs->delivered_ce > 0; + } + + __bpf_kfunc static void bbr_init(struct sock *sk) +@@ -1055,20 +2079,21 @@ __bpf_kfunc static void bbr_init(struct + struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); + +- bbr->prior_cwnd = 0; ++ bbr->initialized = 1; ++ ++ bbr->init_cwnd = min(0x7FU, tcp_snd_cwnd(tp)); ++ bbr->prior_cwnd = tp->prior_cwnd; + tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; +- bbr->rtt_cnt = 0; + bbr->next_rtt_delivered = tp->delivered; + bbr->prev_ca_state = TCP_CA_Open; +- bbr->packet_conservation = 0; + + bbr->probe_rtt_done_stamp = 0; + bbr->probe_rtt_round_done = 0; ++ bbr->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; + +- minmax_reset(&bbr->bw, bbr->rtt_cnt, 0); /* init max bw to 0 */ +- + bbr->has_seen_rtt = 0; + bbr_init_pacing_rate_from_rtt(sk); + +@@ -1079,7 +2104,7 @@ __bpf_kfunc static void bbr_init(struct + bbr->full_bw_cnt = 0; + bbr->cycle_mstamp = 0; + bbr->cycle_idx = 0; +- bbr_reset_lt_bw_sampling(sk); ++ + bbr_reset_startup_mode(sk); + + bbr->ack_epoch_mstamp = tp->tcp_mstamp; +@@ -1089,78 +2114,236 @@ __bpf_kfunc static void bbr_init(struct + bbr->extra_acked[0] = 0; + bbr->extra_acked[1] = 0; + ++ bbr->ce_state = 0; ++ bbr->prior_rcv_nxt = tp->rcv_nxt; ++ bbr->try_fast_path = 0; ++ + cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED); ++ ++ /* Start sampling ECN mark rate after first full flight is ACKed: */ ++ bbr->loss_round_delivered = tp->delivered + 1; ++ bbr->loss_round_start = 0; ++ bbr->undo_bw_lo = 0; ++ bbr->undo_inflight_lo = 0; ++ bbr->undo_inflight_hi = 0; ++ bbr->loss_events_in_round = 0; ++ bbr->startup_ecn_rounds = 0; ++ bbr_reset_congestion_signals(sk); ++ bbr->bw_lo = ~0U; ++ bbr->bw_hi[0] = 0; ++ bbr->bw_hi[1] = 0; ++ bbr->inflight_lo = ~0U; ++ bbr->inflight_hi = ~0U; ++ bbr_reset_full_bw(sk); ++ bbr->bw_probe_up_cnt = ~0U; ++ bbr->bw_probe_up_acks = 0; ++ bbr->bw_probe_up_rounds = 0; ++ bbr->probe_wait_us = 0; ++ bbr->stopped_risky_probe = 0; ++ bbr->ack_phase = BBR_ACKS_INIT; ++ bbr->rounds_since_probe = 0; ++ bbr->bw_probe_samples = 0; ++ bbr->prev_probe_too_high = 0; ++ bbr->ecn_eligible = 0; ++ bbr->ecn_alpha = bbr_param(sk, ecn_alpha_init); ++ bbr->alpha_last_delivered = 0; ++ bbr->alpha_last_delivered_ce = 0; ++ bbr->plb.pause_until = 0; ++ ++ tp->fast_ack_mode = bbr_fast_ack_mode ? 1 : 0; + } + +-__bpf_kfunc static u32 bbr_sndbuf_expand(struct sock *sk) ++/* BBR marks the current round trip as a loss round. */ ++static void bbr_note_loss(struct sock *sk) + { +- /* Provision 3 * cwnd since BBR may slow-start even during recovery. */ +- return 3; ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ ++ /* Capture "current" data over the full round trip of loss, to ++ * have a better chance of observing the full capacity of the path. ++ */ ++ if (!bbr->loss_in_round) /* first loss in this round trip? */ ++ bbr->loss_round_delivered = tp->delivered; /* set round trip */ ++ bbr->loss_in_round = 1; ++ bbr->loss_in_cycle = 1; + } + +-/* In theory BBR does not need to undo the cwnd since it does not +- * always reduce cwnd on losses (see bbr_main()). Keep it for now. +- */ ++/* Core TCP stack informs us that the given skb was just marked lost. */ ++__bpf_kfunc static void bbr_skb_marked_lost(struct sock *sk, ++ const struct sk_buff *skb) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ struct tcp_skb_cb *scb = TCP_SKB_CB(skb); ++ struct rate_sample rs = {}; ++ ++ bbr_note_loss(sk); ++ ++ if (!bbr->bw_probe_samples) ++ return; /* not an skb sent while probing for bandwidth */ ++ if (unlikely(!scb->tx.delivered_mstamp)) ++ return; /* skb was SACKed, reneged, marked lost; ignore it */ ++ /* We are probing for bandwidth. Construct a rate sample that ++ * estimates what happened in the flight leading up to this lost skb, ++ * then see if the loss rate went too high, and if so at which packet. ++ */ ++ rs.tx_in_flight = scb->tx.in_flight; ++ rs.lost = tp->lost - scb->tx.lost; ++ rs.is_app_limited = scb->tx.is_app_limited; ++ if (bbr_is_inflight_too_high(sk, &rs)) { ++ rs.tx_in_flight = bbr_inflight_hi_from_lost_skb(sk, &rs, skb); ++ bbr_handle_inflight_too_high(sk, &rs); ++ } ++} ++ ++static void bbr_run_loss_probe_recovery(struct sock *sk) ++{ ++ struct tcp_sock *tp = tcp_sk(sk); ++ struct bbr *bbr = inet_csk_ca(sk); ++ struct rate_sample rs = {0}; ++ ++ bbr_note_loss(sk); ++ ++ if (!bbr->bw_probe_samples) ++ return; /* not sent while probing for bandwidth */ ++ /* We are probing for bandwidth. Construct a rate sample that ++ * estimates what happened in the flight leading up to this ++ * loss, then see if the loss rate went too high. ++ */ ++ rs.lost = 1; /* TLP probe repaired loss of a single segment */ ++ rs.tx_in_flight = bbr->inflight_latest + rs.lost; ++ rs.is_app_limited = tp->tlp_orig_data_app_limited; ++ if (bbr_is_inflight_too_high(sk, &rs)) ++ bbr_handle_inflight_too_high(sk, &rs); ++} ++ ++/* Revert short-term model if current loss recovery event was spurious. */ + __bpf_kfunc static u32 bbr_undo_cwnd(struct sock *sk) + { + struct bbr *bbr = inet_csk_ca(sk); + +- bbr->full_bw = 0; /* spurious slow-down; reset full pipe detection */ +- bbr->full_bw_cnt = 0; +- bbr_reset_lt_bw_sampling(sk); +- return tcp_snd_cwnd(tcp_sk(sk)); ++ bbr_reset_full_bw(sk); /* spurious slow-down; reset full bw detector */ ++ bbr->loss_in_round = 0; ++ ++ /* Revert to cwnd and other state saved before loss episode. */ ++ bbr->bw_lo = max(bbr->bw_lo, bbr->undo_bw_lo); ++ bbr->inflight_lo = max(bbr->inflight_lo, bbr->undo_inflight_lo); ++ bbr->inflight_hi = max(bbr->inflight_hi, bbr->undo_inflight_hi); ++ bbr->try_fast_path = 0; /* take slow path to set proper cwnd, pacing */ ++ return bbr->prior_cwnd; + } + +-/* Entering loss recovery, so save cwnd for when we exit or undo recovery. */ ++/* Entering loss recovery, so save state for when we undo recovery. */ + __bpf_kfunc static u32 bbr_ssthresh(struct sock *sk) + { ++ struct bbr *bbr = inet_csk_ca(sk); ++ + bbr_save_cwnd(sk); ++ /* For undo, save state that adapts based on loss signal. */ ++ bbr->undo_bw_lo = bbr->bw_lo; ++ bbr->undo_inflight_lo = bbr->inflight_lo; ++ bbr->undo_inflight_hi = bbr->inflight_hi; + return tcp_sk(sk)->snd_ssthresh; + } + ++static enum tcp_bbr_phase bbr_get_phase(struct bbr *bbr) ++{ ++ switch (bbr->mode) { ++ case BBR_STARTUP: ++ return BBR_PHASE_STARTUP; ++ case BBR_DRAIN: ++ return BBR_PHASE_DRAIN; ++ case BBR_PROBE_BW: ++ break; ++ case BBR_PROBE_RTT: ++ return BBR_PHASE_PROBE_RTT; ++ default: ++ return BBR_PHASE_INVALID; ++ } ++ switch (bbr->cycle_idx) { ++ case BBR_BW_PROBE_UP: ++ return BBR_PHASE_PROBE_BW_UP; ++ case BBR_BW_PROBE_DOWN: ++ return BBR_PHASE_PROBE_BW_DOWN; ++ case BBR_BW_PROBE_CRUISE: ++ return BBR_PHASE_PROBE_BW_CRUISE; ++ case BBR_BW_PROBE_REFILL: ++ return BBR_PHASE_PROBE_BW_REFILL; ++ default: ++ return BBR_PHASE_INVALID; ++ } ++} ++ + static size_t bbr_get_info(struct sock *sk, u32 ext, int *attr, +- union tcp_cc_info *info) ++ union tcp_cc_info *info) + { + if (ext & (1 << (INET_DIAG_BBRINFO - 1)) || + ext & (1 << (INET_DIAG_VEGASINFO - 1))) { +- struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); +- u64 bw = bbr_bw(sk); +- +- bw = bw * tp->mss_cache * USEC_PER_SEC >> BW_SCALE; +- memset(&info->bbr, 0, sizeof(info->bbr)); +- info->bbr.bbr_bw_lo = (u32)bw; +- info->bbr.bbr_bw_hi = (u32)(bw >> 32); +- info->bbr.bbr_min_rtt = bbr->min_rtt_us; +- info->bbr.bbr_pacing_gain = bbr->pacing_gain; +- info->bbr.bbr_cwnd_gain = bbr->cwnd_gain; ++ u64 bw = bbr_bw_bytes_per_sec(sk, bbr_bw(sk)); ++ u64 bw_hi = bbr_bw_bytes_per_sec(sk, bbr_max_bw(sk)); ++ u64 bw_lo = bbr->bw_lo == ~0U ? ++ ~0ULL : bbr_bw_bytes_per_sec(sk, bbr->bw_lo); ++ struct tcp_bbr_info *bbr_info = &info->bbr; ++ ++ memset(bbr_info, 0, sizeof(*bbr_info)); ++ bbr_info->bbr_bw_lo = (u32)bw; ++ bbr_info->bbr_bw_hi = (u32)(bw >> 32); ++ bbr_info->bbr_min_rtt = bbr->min_rtt_us; ++ bbr_info->bbr_pacing_gain = bbr->pacing_gain; ++ bbr_info->bbr_cwnd_gain = bbr->cwnd_gain; ++ bbr_info->bbr_bw_hi_lsb = (u32)bw_hi; ++ bbr_info->bbr_bw_hi_msb = (u32)(bw_hi >> 32); ++ bbr_info->bbr_bw_lo_lsb = (u32)bw_lo; ++ bbr_info->bbr_bw_lo_msb = (u32)(bw_lo >> 32); ++ bbr_info->bbr_mode = bbr->mode; ++ bbr_info->bbr_phase = (__u8)bbr_get_phase(bbr); ++ bbr_info->bbr_version = (__u8)BBR_VERSION; ++ bbr_info->bbr_inflight_lo = bbr->inflight_lo; ++ bbr_info->bbr_inflight_hi = bbr->inflight_hi; ++ bbr_info->bbr_extra_acked = bbr_extra_acked(sk); + *attr = INET_DIAG_BBRINFO; +- return sizeof(info->bbr); ++ return sizeof(*bbr_info); + } + return 0; + } + + __bpf_kfunc static void bbr_set_state(struct sock *sk, u8 new_state) + { ++ struct tcp_sock *tp = tcp_sk(sk); + struct bbr *bbr = inet_csk_ca(sk); + + if (new_state == TCP_CA_Loss) { +- struct rate_sample rs = { .losses = 1 }; + + bbr->prev_ca_state = TCP_CA_Loss; +- bbr->full_bw = 0; +- bbr->round_start = 1; /* treat RTO like end of a round */ +- bbr_lt_bw_sampling(sk, &rs); ++ tcp_plb_update_state_upon_rto(sk, &bbr->plb); ++ /* The tcp_write_timeout() call to sk_rethink_txhash() likely ++ * repathed this flow, so re-learn the min network RTT on the ++ * new path: ++ */ ++ bbr_reset_full_bw(sk); ++ if (!bbr_is_probing_bandwidth(sk) && bbr->inflight_lo == ~0U) { ++ /* bbr_adapt_lower_bounds() needs cwnd before ++ * we suffered an RTO, to update inflight_lo: ++ */ ++ bbr->inflight_lo = ++ max(tcp_snd_cwnd(tp), bbr->prior_cwnd); ++ } ++ } else if (bbr->prev_ca_state == TCP_CA_Loss && ++ new_state != TCP_CA_Loss) { ++ bbr_exit_loss_recovery(sk); + } + } + ++ + static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = { +- .flags = TCP_CONG_NON_RESTRICTED, ++ .flags = TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS, + .name = "bbr", + .owner = THIS_MODULE, + .init = bbr_init, + .cong_control = bbr_main, + .sndbuf_expand = bbr_sndbuf_expand, ++ .skb_marked_lost = bbr_skb_marked_lost, + .undo_cwnd = bbr_undo_cwnd, + .cwnd_event = bbr_cwnd_event, + .ssthresh = bbr_ssthresh, +@@ -1175,10 +2358,11 @@ BTF_SET8_START(tcp_bbr_check_kfunc_ids) + BTF_ID_FLAGS(func, bbr_init) + BTF_ID_FLAGS(func, bbr_main) + BTF_ID_FLAGS(func, bbr_sndbuf_expand) ++BTF_ID_FLAGS(func, bbr_skb_marked_lost) + BTF_ID_FLAGS(func, bbr_undo_cwnd) + BTF_ID_FLAGS(func, bbr_cwnd_event) + BTF_ID_FLAGS(func, bbr_ssthresh) +-BTF_ID_FLAGS(func, bbr_min_tso_segs) ++BTF_ID_FLAGS(func, bbr_tso_segs) + BTF_ID_FLAGS(func, bbr_set_state) + #endif + #endif +@@ -1213,5 +2397,12 @@ MODULE_AUTHOR("Van Jacobson "); + MODULE_AUTHOR("Yuchung Cheng "); + MODULE_AUTHOR("Soheil Hassas Yeganeh "); ++MODULE_AUTHOR("Priyaranjan Jha "); ++MODULE_AUTHOR("Yousuk Seung "); ++MODULE_AUTHOR("Kevin Yang "); ++MODULE_AUTHOR("Arjun Roy "); ++MODULE_AUTHOR("David Morley "); ++ + MODULE_LICENSE("Dual BSD/GPL"); + MODULE_DESCRIPTION("TCP BBR (Bottleneck Bandwidth and RTT)"); ++MODULE_VERSION(__stringify(BBR_VERSION)); diff --git a/target/linux/generic/hack-6.6/601-17-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-ensure-ECN-enabled-BBR-flows-set-ECT-.patch b/target/linux/generic/hack-6.6/601-17-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-ensure-ECN-enabled-BBR-flows-set-ECT-.patch new file mode 100644 index 00000000000000..a19a77079639cd --- /dev/null +++ b/target/linux/generic/hack-6.6/601-17-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-ensure-ECN-enabled-BBR-flows-set-ECT-.patch @@ -0,0 +1,58 @@ +From f17f10618636cc35a0b8c3ccee3023dc4c62b956 Mon Sep 17 00:00:00 2001 +From: Adithya Abraham Philip +Date: Fri, 11 Jun 2021 21:56:10 +0000 +Subject: [PATCH 17/19] net-tcp_bbr: v3: ensure ECN-enabled BBR flows set ECT + on retransmits + +Adds a new flag TCP_ECN_ECT_PERMANENT that is used by CCAs to +indicate that retransmitted packets and pure ACKs must have the +ECT bit set. This is necessary for BBR, which when using +ECN expects ECT to be set even on retransmitted packets and ACKs. + +Previous to this addition of TCP_ECN_ECT_PERMANENT, CCAs which can use +ECN but don't "need" it did not have a way to indicate that ECT should +be set on retransmissions/ACKs. + +Signed-off-by: Adithya Abraham Philip +Signed-off-by: Neal Cardwell +Change-Id: I8b048eaab35e136fe6501ef6cd89fd9faa15e6d2 +--- + include/net/tcp.h | 1 + + net/ipv4/tcp_bbr.c | 3 +++ + net/ipv4/tcp_output.c | 3 ++- + 3 files changed, 6 insertions(+), 1 deletion(-) + +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -373,6 +373,7 @@ static inline void tcp_dec_quickack_mode + #define TCP_ECN_DEMAND_CWR 4 + #define TCP_ECN_SEEN 8 + #define TCP_ECN_LOW 16 ++#define TCP_ECN_ECT_PERMANENT 32 + + enum tcp_tw_status { + TCP_TW_SUCCESS = 0, +--- a/net/ipv4/tcp_bbr.c ++++ b/net/ipv4/tcp_bbr.c +@@ -2151,6 +2151,9 @@ __bpf_kfunc static void bbr_init(struct + bbr->plb.pause_until = 0; + + tp->fast_ack_mode = bbr_fast_ack_mode ? 1 : 0; ++ ++ if (bbr_can_use_ecn(sk)) ++ tp->ecn_flags |= TCP_ECN_ECT_PERMANENT; + } + + /* BBR marks the current round trip as a loss round. */ +--- a/net/ipv4/tcp_output.c ++++ b/net/ipv4/tcp_output.c +@@ -388,7 +388,8 @@ static void tcp_ecn_send(struct sock *sk + 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); + } diff --git a/target/linux/generic/hack-6.6/601-18-bbr-v3-upstream-prep-2024-02-19-01-tcp-export-TCPI_OPT_ECN_LOW-in-tcp_info-tcpi_options.patch b/target/linux/generic/hack-6.6/601-18-bbr-v3-upstream-prep-2024-02-19-01-tcp-export-TCPI_OPT_ECN_LOW-in-tcp_info-tcpi_options.patch new file mode 100644 index 00000000000000..7440a33eb41d1a --- /dev/null +++ b/target/linux/generic/hack-6.6/601-18-bbr-v3-upstream-prep-2024-02-19-01-tcp-export-TCPI_OPT_ECN_LOW-in-tcp_info-tcpi_options.patch @@ -0,0 +1,37 @@ +From 00a264b290051753e189ec6eadbd0cad3067b77d Mon Sep 17 00:00:00 2001 +From: Neal Cardwell +Date: Sun, 23 Jul 2023 23:25:34 -0400 +Subject: [PATCH 18/19] tcp: export TCPI_OPT_ECN_LOW in tcp_info tcpi_options + field + +Analogous to other important ECN information, export TCPI_OPT_ECN_LOW +in tcp_info tcpi_options field. + +Signed-off-by: Neal Cardwell +Change-Id: I08d8d8c7e8780e6e37df54038ee50301ac5a0320 +--- + include/uapi/linux/tcp.h | 1 + + net/ipv4/tcp.c | 2 ++ + 2 files changed, 3 insertions(+) + +--- a/include/uapi/linux/tcp.h ++++ b/include/uapi/linux/tcp.h +@@ -170,6 +170,7 @@ enum tcp_fastopen_client_fail { + #define TCPI_OPT_ECN 8 /* ECN was negociated at TCP session init */ + #define TCPI_OPT_ECN_SEEN 16 /* we received at least one packet with ECT */ + #define TCPI_OPT_SYN_DATA 32 /* SYN-ACK acked data in SYN sent or rcvd */ ++#define TCPI_OPT_ECN_LOW 64 /* Low-latency ECN configured at init */ + + /* + * Sender's congestion state indicating normal or abnormal situations +--- a/net/ipv4/tcp.c ++++ b/net/ipv4/tcp.c +@@ -3791,6 +3791,8 @@ void tcp_get_info(struct sock *sk, struc + info->tcpi_options |= TCPI_OPT_ECN; + if (tp->ecn_flags & TCP_ECN_SEEN) + info->tcpi_options |= TCPI_OPT_ECN_SEEN; ++ if (tp->ecn_flags & TCP_ECN_LOW) ++ info->tcpi_options |= TCPI_OPT_ECN_LOW; + if (tp->syn_data_acked) + info->tcpi_options |= TCPI_OPT_SYN_DATA; + diff --git a/target/linux/generic/hack-6.6/601-19-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-change-u64-to-unsigned-long-for-bytes.patch b/target/linux/generic/hack-6.6/601-19-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-change-u64-to-unsigned-long-for-bytes.patch new file mode 100644 index 00000000000000..f1d55df7a5d41f --- /dev/null +++ b/target/linux/generic/hack-6.6/601-19-bbr-v3-upstream-prep-2024-02-19-01-net-tcp_bbr-v3-change-u64-to-unsigned-long-for-bytes.patch @@ -0,0 +1,36 @@ +From 5ccaffc5456985926897afe8c79fa21a612eec70 Mon Sep 17 00:00:00 2001 +From: Chen Minqiang +Date: Sat, 21 Sep 2024 23:51:24 +0800 +Subject: [PATCH 19/19] net-tcp_bbr: v3: change `u64` to `unsigned long` for + `bytes` in `bbr_tso_segs_generic` + +This change addresses a build failure on 32-bit systems due to undefined division symbols: + +arm: +ERROR: modpost: "__aeabi_uldivmod" [net/ipv4/tcp_bbr.ko] undefined! +ERROR: modpost: "__aeabi_ldivmod" [net/ipv4/tcp_bbr.ko] undefined! + +x86, mips, ppc: +ERROR: modpost: "__udivdi3" [net/ipv4/tcp_bbr.ko] undefined! +ERROR: modpost: "__divdi3" [net/ipv4/tcp_bbr.ko] undefined! + +Since `sk->sk_pacing_rate` is already an `unsigned long`, the `bytes` variable is +updated to `unsigned long` to resolve these division issues and ensure compatibility +across both 32-bit and 64-bit platforms. + +Signed-off-by: Chen Minqiang +--- + net/ipv4/tcp_bbr.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +--- a/net/ipv4/tcp_bbr.c ++++ b/net/ipv4/tcp_bbr.c +@@ -481,7 +481,7 @@ static u32 bbr_tso_segs_generic(struct s + { + struct bbr *bbr = inet_csk_ca(sk); + u32 segs, r; +- u64 bytes; ++ unsigned long bytes; + + /* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */ + bytes = sk->sk_pacing_rate >> sk->sk_pacing_shift;