NetBSD Problem Report #34748
From yamt@mwd.biglobe.ne.jp Sat Oct 7 21:43:12 2006
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Date: Sun, 8 Oct 2006 05:09:22 +0900 (JST)
From: yamt@mwd.biglobe.ne.jp
Reply-To: yamt@mwd.biglobe.ne.jp
To: gnats-bugs@NetBSD.org
Subject: our tcp stack can enter fast recovery due to DSACKs
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>Number: 34748
>Category: kern
>Synopsis: our tcp stack can enter fast recovery due to DSACKs
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: kern-bug-people
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Sat Oct 07 21:45:02 +0000 2006
>Closed-Date:
>Last-Modified: Tue Jan 29 12:36:04 +0000 2008
>Originator: YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>
>Release: NetBSD 4.99.3
>Organization:
>Environment:
System: NetBSD 4.99.3
Architecture: i386
Machine: i386
>Description:
our tcp stack can treat DSACKs as pure dupacks and enter fast recovery
erroneously.
>How-To-Repeat:
code inspection.
>Fix:
Index: netinet/tcp_input.c
===================================================================
--- netinet/tcp_input.c (revision 1807)
+++ netinet/tcp_input.c (revision 1808)
@@ -2276,7 +2276,8 @@ after_listen:
th->th_ack != tp->snd_una)
tp->t_dupacks = 0;
else if (tp->t_partialacks < 0 &&
- (++tp->t_dupacks == tcprexmtthresh ||
+ ((!TCP_SACK_ENABLED(tp) &&
+ ++tp->t_dupacks == tcprexmtthresh) ||
TCP_FACK_FASTRECOV(tp))) {
tcp_seq onxt;
>Release-Note:
>Audit-Trail:
From: YAMAMOTO Takashi <yamt@netbsd.org>
To: gnats-bugs@NetBSD.org
Cc:
Subject: PR/34748 CVS commit: src/sys/netinet
Date: Tue, 17 Oct 2006 09:31:17 +0000 (UTC)
Module Name: src
Committed By: yamt
Date: Tue Oct 17 09:31:17 UTC 2006
Modified Files:
src/sys/netinet: tcp_input.c
Log Message:
tcp_input: if we have SACK, don't enter fastrecovery on three dupacks.
otherwise, we can enter fastrecovery due to DSACKs, which we treat
as dupacks here. PR/34748. reviewed by Rui Paulo.
To generate a diff of this commit:
cvs rdiff -r1.252 -r1.253 src/sys/netinet/tcp_input.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
State-Changed-From-To: open->closed
State-Changed-By: yamt@netbsd.org
State-Changed-When: Tue, 17 Oct 2006 11:13:13 +0000
State-Changed-Why:
fixed.
State-Changed-From-To: closed->open
State-Changed-By: yamt@narn.netbsd.org
State-Changed-When: Tue, 29 Jan 2008 12:36:04 +0000
State-Changed-Why:
the fix was reverted.
>Unformatted:
(Contact us)
$NetBSD: query-full-pr,v 1.39 2013/11/01 18:47:49 spz Exp $
$NetBSD: gnats_config.sh,v 1.8 2006/05/07 09:23:38 tsutsui Exp $
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