The branch main has been updated by rscheff: URL: https://cgit.FreeBSD.org/src/commit/?id=0b3f9e435f2bde9e5be27030d9f574a977a1ad47
commit 0b3f9e435f2bde9e5be27030d9f574a977a1ad47 Author: Richard Scheffenegger <[email protected]> AuthorDate: 2024-01-27 23:16:59 +0000 Commit: Richard Scheffenegger <[email protected]> CommitDate: 2024-01-27 23:18:51 +0000 tcp: move cc_post_recovery past snd_una update The RFC6675 pipe calculation (sack.revised, enabled by default since D28702), uses outdated information, while the previous default calculated it correctly with up-to-date information from the incoming ACK. This difference can become as large as the receive window (not the congestion window previously), potentially triggering a massive burst of new packets. MFC after: 1 week Reviewed By: tuexen, #transport Sponsored by: NetApp, Inc. Differential Revision: https://reviews.freebsd.org/D43520 --- sys/netinet/tcp_input.c | 50 ++++++++++++++++++++++--------------------------- 1 file changed, 22 insertions(+), 28 deletions(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 98564ff67f22..afcda60137ec 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -474,13 +474,12 @@ cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) { INP_WLOCK_ASSERT(tptoinpcb(tp)); - /* XXXLAS: KASSERT that we're in recovery? */ - if (CC_ALGO(tp)->post_recovery != NULL) { tp->t_ccv.curack = th->th_ack; CC_ALGO(tp)->post_recovery(&tp->t_ccv); } - /* XXXLAS: EXIT_RECOVERY ? */ + EXIT_RECOVERY(tp->t_flags); + tp->t_bytes_acked = 0; tp->sackhint.delivered_data = 0; tp->sackhint.prr_delivered = 0; @@ -2813,11 +2812,13 @@ resume_partialack: * If the congestion window was inflated to account * for the other side's cached packets, retract it. */ - if (IN_FASTRECOVERY(tp->t_flags)) { - if (SEQ_LT(th->th_ack, tp->snd_recover)) { + if (SEQ_LT(th->th_ack, tp->snd_recover)) { + if (IN_FASTRECOVERY(tp->t_flags)) { if (tp->t_flags & TF_SACK_PERMIT) { - if (V_tcp_do_prr && to.to_flags & TOF_SACK) { - tcp_timer_activate(tp, TT_REXMT, 0); + if (V_tcp_do_prr && + (to.to_flags & TOF_SACK)) { + tcp_timer_activate(tp, + TT_REXMT, 0); tp->t_rtttime = 0; tcp_do_prr_ack(tp, th, &to, sack_changed, &maxseg); @@ -2830,24 +2831,18 @@ resume_partialack: } else { tcp_newreno_partial_ack(tp, th); } - } else { - cc_post_recovery(tp, th); - } - } else if (IN_CONGRECOVERY(tp->t_flags)) { - if (SEQ_LT(th->th_ack, tp->snd_recover)) { - if (V_tcp_do_prr) { - tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); - tp->snd_fack = th->th_ack; - /* - * During ECN cwnd reduction - * always use PRR-SSRB - */ - tcp_do_prr_ack(tp, th, &to, SACK_CHANGE, - &maxseg); - (void) tcp_output(tp); - } - } else { - cc_post_recovery(tp, th); + } else if (IN_CONGRECOVERY(tp->t_flags) && + (V_tcp_do_prr)) { + tp->sackhint.delivered_data = + BYTES_THIS_ACK(tp, th); + tp->snd_fack = th->th_ack; + /* + * During ECN cwnd reduction + * always use PRR-SSRB + */ + tcp_do_prr_ack(tp, th, &to, SACK_CHANGE, + &maxseg); + (void) tcp_output(tp); } } /* @@ -2999,12 +2994,11 @@ process_ACK: SEQ_GT(tp->snd_una, tp->snd_recover) && SEQ_LEQ(th->th_ack, tp->snd_recover)) tp->snd_recover = th->th_ack - 1; - /* XXXLAS: Can this be moved up into cc_post_recovery? */ + tp->snd_una = th->th_ack; if (IN_RECOVERY(tp->t_flags) && SEQ_GEQ(th->th_ack, tp->snd_recover)) { - EXIT_RECOVERY(tp->t_flags); + cc_post_recovery(tp, th); } - tp->snd_una = th->th_ack; if (tp->t_flags & TF_SACK_PERMIT) { if (SEQ_GT(tp->snd_una, tp->snd_recover)) tp->snd_recover = tp->snd_una;
