Date: Mon, 5 Feb 2024 11:41:48 GMT From: Richard Scheffenegger <rscheff@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 9bc48382a5e8 - stable/14 - tcp: move cc_post_recovery past snd_una update Message-ID: <202402051141.415Bfmuw075444@gitrepo.freebsd.org>
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The branch stable/14 has been updated by rscheff: URL: https://cgit.FreeBSD.org/src/commit/?id=9bc48382a5e8260b3240b4cd99d984ada55f0990 commit 9bc48382a5e8260b3240b4cd99d984ada55f0990 Author: Richard Scheffenegger <rscheff@FreeBSD.org> AuthorDate: 2024-01-27 23:16:59 +0000 Commit: Richard Scheffenegger <rscheff@FreeBSD.org> CommitDate: 2024-02-01 18:13:53 +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cc_post_recovery past snd_una update The RFC6675 pipe calculation (sack.revised, enabled by default since D28702), uses outdated information, while the previous default calculated it correctly with up-to-date information from the incoming ACK.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 (cherry picked from commit 0b3f9e435f2bde9e5be27030d9f574a977a1ad47) --- sys/netinet/tcp_input.c | 57 ++++++++++++++++++++++++------------------------- 1 file changed, 28 insertions(+), 29 deletions(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 38498370ceb2..2a4f3875d1b9 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -478,13 +478,12 @@ 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; @@ -2803,35 +2802,36 @@ 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 (tp->t_flags & TF_SACK_PERMIT) - if (V_tcp_do_prr && to.to_flags & TOF_SACK) { - tcp_timer_activate(tp, TT_REXMT, 0); + 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); tp->t_rtttime = 0; - tcp_do_prr_ack(tp, th, &to, sack_changed); + tcp_do_prr_ack(tp, th, &to, + sack_changed); tp->t_flags |= TF_ACKNOW; (void) tcp_output(tp); - } else + } else { tcp_sack_partialack(tp, th); - else + } + } 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); - (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); + (void) tcp_output(tp); + } } /* * If we reach this point, ACK is not a duplicate, @@ -2982,12 +2982,11 @@ 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;
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