Date: Fri, 05 Dec 2025 13:10:59 +0000 From: Richard Scheffenegger <rscheff@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 9155d4b273ff - main - tcp: retire do_newsack - always adhere to RFC6675 SACK Message-ID: <6932d9e3.289f7.62b6656@gitrepo.freebsd.org>
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The branch main has been updated by rscheff: URL: https://cgit.FreeBSD.org/src/commit/?id=9155d4b273ffc07e81e2cb0bcedfac570d14a303 commit 9155d4b273ffc07e81e2cb0bcedfac570d14a303 Author: Richard Scheffenegger <rscheff@FreeBSD.org> AuthorDate: 2025-12-05 11:29:15 +0000 Commit: Richard Scheffenegger <rscheff@FreeBSD.org> CommitDate: 2025-12-05 13:10:37 +0000 tcp: retire do_newsack - always adhere to RFC6675 SACK Depreciation notice for net.inet.tcp.newsack is in 15.0. Remove this tunable for HEAD, streamlining the code slightly. Reviewed by: tuexen, cc, nickbanks_netflix.com, #transport Sponsored by: NetApp, Inc. Differential Revision: https://reviews.freebsd.org/D54072 --- sys/netinet/tcp_input.c | 11 +++-------- sys/netinet/tcp_sack.c | 41 +---------------------------------------- sys/netinet/tcp_stacks/rack.c | 4 ++-- sys/netinet/tcp_var.h | 2 -- 4 files changed, 6 insertions(+), 52 deletions(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 0036a07384ae..c015995ffc7a 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -2535,8 +2535,7 @@ tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, } if (th->th_ack == tp->snd_una) { /* Check if this is a duplicate ACK. */ - if ((tp->t_flags & TF_SACK_PERMIT) && - V_tcp_do_newsack) { + if (tp->t_flags & TF_SACK_PERMIT) { /* * If SEG.ACK == SND.UNA, RFC 6675 requires a * duplicate ACK to selectively acknowledge @@ -2613,7 +2612,6 @@ tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, goto drop; } else if (tp->t_dupacks == tcprexmtthresh || (tp->t_flags & TF_SACK_PERMIT && - V_tcp_do_newsack && tp->sackhint.sacked_bytes > (tcprexmtthresh - 1) * maxseg)) { enter_recovery: @@ -2780,8 +2778,7 @@ enter_recovery: * from the left side. Such partial ACKs should not be * counted as dupacks here. */ - if (V_tcp_do_newsack && - tcp_is_sack_recovery(tp, &to) && + if (tcp_is_sack_recovery(tp, &to) && (((tp->t_rxtshift == 0) && (sack_changed != SACK_NOCHANGE)) || ((tp->t_rxtshift > 0) && (sack_changed == SACK_NEWLOSS))) && (tp->snd_nxt == tp->snd_max)) { @@ -4120,13 +4117,11 @@ tcp_compute_pipe(struct tcpcb *tp) if (tp->t_fb->tfb_compute_pipe != NULL) { pipe = (*tp->t_fb->tfb_compute_pipe)(tp); - } else if (V_tcp_do_newsack) { + } else { pipe = tp->snd_max - tp->snd_una + tp->sackhint.sack_bytes_rexmit - tp->sackhint.sacked_bytes - tp->sackhint.lost_bytes; - } else { - pipe = tp->snd_nxt - tp->snd_fack + tp->sackhint.sack_bytes_rexmit; } return (imax(pipe, 0)); } diff --git a/sys/netinet/tcp_sack.c b/sys/netinet/tcp_sack.c index 13cc7b0de157..f31e88eda41a 100644 --- a/sys/netinet/tcp_sack.c +++ b/sys/netinet/tcp_sack.c @@ -126,28 +126,6 @@ SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_do_sack), 0, "Enable/Disable TCP SACK support"); -VNET_DEFINE(int, tcp_do_newsack) = 1; - -static int -sysctl_net_inet_tcp_sack_revised(SYSCTL_HANDLER_ARGS) -{ - int error; - int new; - - new = V_tcp_do_newsack; - error = sysctl_handle_int(oidp, &new, 0, req); - if (error == 0 && req->newptr) { - V_tcp_do_newsack = new; - gone_in(16, "net.inet.tcp.sack.revised will be deprecated." - " net.inet.tcp.sack.enable will always follow RFC6675 SACK.\n"); - } - return (error); -} - -SYSCTL_PROC(_net_inet_tcp_sack, OID_AUTO, revised, CTLFLAG_VNET | CTLFLAG_RW | CTLTYPE_INT, - &VNET_NAME(tcp_do_newsack), 0, sysctl_net_inet_tcp_sack_revised, "CU", - "Use revised SACK loss recovery per RFC 6675"); - VNET_DEFINE(int, tcp_do_lrd) = 1; SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, lrd, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_do_lrd), 1, @@ -1013,8 +991,7 @@ tcp_sack_partialack(struct tcpcb *tp, struct tcphdr *th, u_int *maxsegp) * the trailing packets of a window are lost and no further data * is available for sending. */ - if ((V_tcp_do_newsack) && - SEQ_LT(th->th_ack, tp->snd_recover) && + if (SEQ_LT(th->th_ack, tp->snd_recover) && TAILQ_EMPTY(&tp->snd_holes) && (tp->sackhint.delivered_data > 0)) { /* @@ -1079,22 +1056,6 @@ tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt) } KASSERT(SEQ_LT(hole->start, hole->end), ("%s: SEQ_GEQ(hole.start, hole.end)", __func__)); - if (!(V_tcp_do_newsack)) { - KASSERT(SEQ_LT(hole->start, tp->snd_fack), - ("%s: SEG_GEQ(hole.start, snd.fack)", __func__)); - KASSERT(SEQ_LT(hole->end, tp->snd_fack), - ("%s: SEG_GEQ(hole.end, snd.fack)", __func__)); - KASSERT(SEQ_LT(hole->rxmit, tp->snd_fack), - ("%s: SEQ_GEQ(hole.rxmit, snd.fack)", __func__)); - if (SEQ_GEQ(hole->start, hole->end) || - SEQ_GEQ(hole->start, tp->snd_fack) || - SEQ_GEQ(hole->end, tp->snd_fack) || - SEQ_GEQ(hole->rxmit, tp->snd_fack)) { - log(LOG_CRIT,"tcp: invalid SACK hole (%u-%u,%u) vs fwd ack %u, ignoring.\n", - hole->start, hole->end, hole->rxmit, tp->snd_fack); - return (NULL); - } - } return (hole); } diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c index 9ed26d5a617b..76bf8f2e3b17 100644 --- a/sys/netinet/tcp_stacks/rack.c +++ b/sys/netinet/tcp_stacks/rack.c @@ -5393,7 +5393,7 @@ rack_ack_received(struct tcpcb *tp, struct tcp_rack *rack, uint32_t th_ack, uint log.u_bbr.flex4 = tp->t_ccv.nsegs; log.u_bbr.flex5 = labc_to_use; log.u_bbr.flex6 = prior_cwnd; - log.u_bbr.flex7 = V_tcp_do_newsack; + log.u_bbr.flex7 = 1; /* always doing RFC6675 SACK */ log.u_bbr.flex8 = 1; lgb = tcp_log_event(tp, NULL, NULL, NULL, BBR_LOG_CWND, 0, 0, &log, false, NULL, __func__, __LINE__,&tv); @@ -5508,7 +5508,7 @@ rack_post_recovery(struct tcpcb *tp, uint32_t th_ack) log.u_bbr.flex4 = tp->t_ccv.nsegs; log.u_bbr.flex5 = V_tcp_abc_l_var; log.u_bbr.flex6 = orig_cwnd; - log.u_bbr.flex7 = V_tcp_do_newsack; + log.u_bbr.flex7 = 1; /* always doing RFC6675 SACK */ log.u_bbr.pkts_out = rack->r_ctl.rc_prr_sndcnt; log.u_bbr.flex8 = 2; tcp_log_event(tp, NULL, NULL, NULL, BBR_LOG_CWND, 0, diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h index f9297be46af7..7f836f5a1df4 100644 --- a/sys/netinet/tcp_var.h +++ b/sys/netinet/tcp_var.h @@ -1308,7 +1308,6 @@ VNET_DECLARE(int, tcp_tolerate_missing_ts); VNET_DECLARE(int, tcp_do_rfc3042); VNET_DECLARE(int, tcp_do_rfc3390); VNET_DECLARE(int, tcp_do_rfc3465); -VNET_DECLARE(int, tcp_do_newsack); VNET_DECLARE(int, tcp_do_sack); VNET_DECLARE(int, tcp_do_tso); VNET_DECLARE(int, tcp_ecn_maxretries); @@ -1359,7 +1358,6 @@ VNET_DECLARE(struct inpcbinfo, tcbinfo); #define V_tcp_do_rfc3042 VNET(tcp_do_rfc3042) #define V_tcp_do_rfc3390 VNET(tcp_do_rfc3390) #define V_tcp_do_rfc3465 VNET(tcp_do_rfc3465) -#define V_tcp_do_newsack VNET(tcp_do_newsack) #define V_tcp_do_sack VNET(tcp_do_sack) #define V_tcp_do_tso VNET(tcp_do_tso) #define V_tcp_ecn_maxretries VNET(tcp_ecn_maxretries)help
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