From owner-dev-commits-src-all@freebsd.org Tue Jan 26 15:09:04 2021 Return-Path: Delivered-To: dev-commits-src-all@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 789E44F22F8; Tue, 26 Jan 2021 15:09:04 +0000 (UTC) (envelope-from git@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 "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4DQ99r33SCz4WLM; Tue, 26 Jan 2021 15:09:04 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (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 did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 5B72B3895; Tue, 26 Jan 2021 15:09:04 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 10QF94sp005232; Tue, 26 Jan 2021 15:09:04 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 10QF94iV005231; Tue, 26 Jan 2021 15:09:04 GMT (envelope-from git) Date: Tue, 26 Jan 2021 15:09:04 GMT Message-Id: <202101261509.10QF94iV005231@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Richard Scheffenegger Subject: git: 6a376af0cd21 - main - TCP PRR: Patch div/0 in tcp_prr_partialack MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: rscheff X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 6a376af0cd212be4e16d013d35a0e2eec1dbb8ae Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for all branches of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Jan 2021 15:09:04 -0000 The branch main has been updated by rscheff: URL: https://cgit.FreeBSD.org/src/commit/?id=6a376af0cd212be4e16d013d35a0e2eec1dbb8ae commit 6a376af0cd212be4e16d013d35a0e2eec1dbb8ae Author: Richard Scheffenegger AuthorDate: 2021-01-26 15:06:32 +0000 Commit: Richard Scheffenegger CommitDate: 2021-01-26 15:06:32 +0000 TCP PRR: Patch div/0 in tcp_prr_partialack With clearing of recover_fs in bc7ee8e5bc555, div/0 was observed while processing partial_acks. Suspect that rewind of an erraneous RTO may be causing this - with the above change, recover_fs would no longer retained at the last calculated value, and reset. But CC_RTO_ERR can reenable IN_RECOVERY(), without setting this again. Adding a safety net prior to the division in that function, which I missed in D28114. --- sys/netinet/tcp_input.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 4b8f91ed9d0b..459b78cd444a 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -510,7 +510,6 @@ cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) } /* XXXLAS: EXIT_RECOVERY ? */ tp->t_bytes_acked = 0; - tp->sackhint.recover_fs = 0; } /* @@ -3948,10 +3947,13 @@ tcp_prr_partialack(struct tcpcb *tp, struct tcphdr *th) /* * Proportional Rate Reduction */ - if (pipe > tp->snd_ssthresh) + if (pipe > tp->snd_ssthresh) { + if (tp->sackhint.recover_fs == 0) + tp->sackhint.recover_fs = + max(1, tp->snd_nxt - tp->snd_una); snd_cnt = (tp->sackhint.prr_delivered * tp->snd_ssthresh / tp->sackhint.recover_fs) - tp->sackhint.sack_bytes_rexmit; - else { + } else { if (V_tcp_do_prr_conservative) limit = tp->sackhint.prr_delivered - tp->sackhint.sack_bytes_rexmit;