From owner-svn-src-stable-12@freebsd.org Wed Jun 24 16:17:59 2020 Return-Path: Delivered-To: svn-src-stable-12@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 74E6A35235B; Wed, 24 Jun 2020 16:17:59 +0000 (UTC) (envelope-from rscheff@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 49sSx32VcLz4LkL; Wed, 24 Jun 2020 16:17:59 +0000 (UTC) (envelope-from rscheff@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 5112B14640; Wed, 24 Jun 2020 16:17:59 +0000 (UTC) (envelope-from rscheff@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 05OGHxkE033098; Wed, 24 Jun 2020 16:17:59 GMT (envelope-from rscheff@FreeBSD.org) Received: (from rscheff@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 05OGHwkX033096; Wed, 24 Jun 2020 16:17:58 GMT (envelope-from rscheff@FreeBSD.org) Message-Id: <202006241617.05OGHwkX033096@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: rscheff set sender to rscheff@FreeBSD.org using -f From: Richard Scheffenegger Date: Wed, 24 Jun 2020 16:17:58 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r362586 - in stable/12/sys/netinet: . tcp_stacks X-SVN-Group: stable-12 X-SVN-Commit-Author: rscheff X-SVN-Commit-Paths: in stable/12/sys/netinet: . tcp_stacks X-SVN-Commit-Revision: 362586 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-stable-12@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for only the 12-stable src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Jun 2020 16:17:59 -0000 Author: rscheff Date: Wed Jun 24 16:17:58 2020 New Revision: 362586 URL: https://svnweb.freebsd.org/changeset/base/362586 Log: 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 continous reduction of the congestion window, and very poor performance when ECN is enabled. PR: 243590 Reviewed by: rgrimes (mentor), rrs Approved by: rgrimes (mentor, blanket) MFC after: 3 weeks Sponsored by: NetApp, Inc. Differential Revision: https://reviews.freebsd.org/D23364 Modified: stable/12/sys/netinet/tcp_input.c stable/12/sys/netinet/tcp_output.c stable/12/sys/netinet/tcp_stacks/rack.c Directory Properties: stable/12/ (props changed) Modified: stable/12/sys/netinet/tcp_input.c ============================================================================== --- stable/12/sys/netinet/tcp_input.c Wed Jun 24 15:46:33 2020 (r362585) +++ stable/12/sys/netinet/tcp_input.c Wed Jun 24 16:17:58 2020 (r362586) @@ -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: stable/12/sys/netinet/tcp_output.c ============================================================================== --- stable/12/sys/netinet/tcp_output.c Wed Jun 24 15:46:33 2020 (r362585) +++ stable/12/sys/netinet/tcp_output.c Wed Jun 24 16:17:58 2020 (r362586) @@ -1132,7 +1132,8 @@ 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); @@ -1140,15 +1141,15 @@ 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; } Modified: stable/12/sys/netinet/tcp_stacks/rack.c ============================================================================== --- stable/12/sys/netinet/tcp_stacks/rack.c Wed Jun 24 15:46:33 2020 (r362585) +++ stable/12/sys/netinet/tcp_stacks/rack.c Wed Jun 24 16:17:58 2020 (r362586) @@ -1415,9 +1415,15 @@ rack_cong_signal(struct tcpcb *tp, struct tcphdr *th, } 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; } @@ -8283,13 +8289,14 @@ send: #endif ip->ip_tos |= IPTOS_ECN_ECT0; TCPSTAT_INC(tcps_ecn_ect0); - } - /* - * Reply with proper ECN notifications. - */ - if (tp->t_flags & TF_ECN_SND_CWR) { - flags |= TH_CWR; - tp->t_flags &= ~TF_ECN_SND_CWR; + /* + * 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; + } } if (tp->t_flags & TF_ECN_SND_ECE) flags |= TH_ECE;