Author: rscheff Date: Wed May 27 22:34:46 2020 New Revision: 361565 URL: https://svnweb.freebsd.org/changeset/base/361565
Log: MFS r361436: MFC r361347: With RFC3168 ECN, CWR SHOULD only be sent with new data. Overly conservative data receivers may ignore the CWR flag on other packets, and keep ECE latched. This can result in continuous reduction of the congestion window, and very poor performance when ECN is enabled. This does NOT contain the merge of the change to RACK since at this time that code does not exist in stable/11, and there is no plan to merge RACK to stable/11. PR: 243590 Reviewed by: rgrimes (mentor), rrs Approved by: re(gjb) Sponsored by: NetApp, Inc. Differential Revision: https://reviews.freebsd.org/D23364 Modified: releng/11.4/sys/netinet/tcp_input.c releng/11.4/sys/netinet/tcp_output.c Directory Properties: releng/11.4/ (props changed) Modified: releng/11.4/sys/netinet/tcp_input.c ============================================================================== --- releng/11.4/sys/netinet/tcp_input.c Wed May 27 21:56:45 2020 (r361564) +++ releng/11.4/sys/netinet/tcp_input.c Wed May 27 22:34:46 2020 (r361565) @@ -417,9 +417,15 @@ cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, ui } break; case CC_ECN: - if (!IN_CONGRECOVERY(tp->t_flags)) { + if (!IN_CONGRECOVERY(tp->t_flags) || + /* + * Allow ECN reaction on ACK to CWR, if + * that data segment was also CE marked. + */ + SEQ_GEQ(th->th_ack, tp->snd_recover)) { + EXIT_CONGRECOVERY(tp->t_flags); TCPSTAT_INC(tcps_ecn_rcwnd); - tp->snd_recover = tp->snd_max; + tp->snd_recover = tp->snd_max + 1; if (tp->t_flags & TF_ECN_PERMIT) tp->t_flags |= TF_ECN_SND_CWR; } Modified: releng/11.4/sys/netinet/tcp_output.c ============================================================================== --- releng/11.4/sys/netinet/tcp_output.c Wed May 27 21:56:45 2020 (r361564) +++ releng/11.4/sys/netinet/tcp_output.c Wed May 27 22:34:46 2020 (r361565) @@ -1161,7 +1161,8 @@ send: * Ignore pure ack packets, retransmissions and window probes. */ if (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) && - !((tp->t_flags & TF_FORCEDATA) && len == 1)) { + !((tp->t_flags & TF_FORCEDATA) && len == 1 && + SEQ_LT(tp->snd_una, tp->snd_max))) { #ifdef INET6 if (isipv6) ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); @@ -1169,15 +1170,15 @@ send: #endif ip->ip_tos |= IPTOS_ECN_ECT0; TCPSTAT_INC(tcps_ecn_ect0); + /* + * Reply with proper ECN notifications. + * Only set CWR on new data segments. + */ + if (tp->t_flags & TF_ECN_SND_CWR) { + flags |= TH_CWR; + tp->t_flags &= ~TF_ECN_SND_CWR; + } } - - /* - * Reply with proper ECN notifications. - */ - if (tp->t_flags & TF_ECN_SND_CWR) { - flags |= TH_CWR; - tp->t_flags &= ~TF_ECN_SND_CWR; - } if (tp->t_flags & TF_ECN_SND_ECE) flags |= TH_ECE; } _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
