NetBSD Problem Report #55030
From christos@astron.com Fri Feb 28 17:47:31 2020
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Message-Id: <20200228163145.9062C10756@quasar.astron.com>
Date: Fri, 28 Feb 2020 16:31:45 +0000 (UTC)
From: christos@netbsd.org
Reply-To: christos@astron.com
To: gnats-bugs@NetBSD.org
Subject: nd6_llinfo_timer causes locking against myself
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>Number: 55030
>Category: kern
>Synopsis: nd6_llinfo_timer causes locking against myself
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: kern-bug-people
>State: closed
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Fri Feb 28 17:50:00 +0000 2020
>Closed-Date: Sun Jul 25 02:47:54 +0000 2021
>Last-Modified: Sun Jul 25 02:47:54 +0000 2021
>Originator: Christos Zoulas
>Release: NetBSD 9.99.48
>Organization:
Entropy Anonymous
>Environment:
System: NetBSD quasar.astron.com 9.99.48 NetBSD 9.99.48 (QUASAR) #76: Thu Feb 27 22:02:36 EST 2020 christos@quasar.astron.com:/usr/src/sys/arch/amd64/compile/QUASAR amd64
Architecture: x86_64
Machine: amd64
>Description:
path throu in6_lltable_lookup tries to lock lle entry locked by
nd6_llinfo_timer.
>How-To-Repeat:
Normal running of the network
>Fix:
Wait for timer processing to finish before taking the lock (blocking
on softint?) This seems to work so far...
Index: nd6.c
===================================================================
RCS file: /cvsroot/src/sys/netinet6/nd6.c,v
retrieving revision 1.267
diff -u -u -r1.267 nd6.c
--- nd6.c 9 Mar 2020 21:20:56 -0000 1.267
+++ nd6.c 22 Mar 2020 18:13:40 -0000
@@ -466,7 +466,11 @@
SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();
- LLE_WLOCK(ln);
+ LLE_RLOCK(ln);
+ if (!LLE_TRY_UPGRADE(ln)) {
+ LLE_RUNLOCK(ln);
+ goto out;
+ }
if ((ln->la_flags & LLE_LINKED) == 0)
goto out;
if (ln->ln_ntick > 0) {
Panic:
https://www.zoulas.com/~christos/NetBSD/nd6.png
>Release-Note:
>Audit-Trail:
From: "Christos Zoulas" <christos@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc:
Subject: PR/55030 CVS commit: src/sys/netinet6
Date: Fri, 3 Apr 2020 10:04:27 -0400
Module Name: src
Committed By: christos
Date: Fri Apr 3 14:04:27 UTC 2020
Modified Files:
src/sys/netinet6: nd6.c
Log Message:
PR/55030: Avoid locking against myself panic by moving the icmp error outside
the lock. Thanks ozaki-r!
To generate a diff of this commit:
cvs rdiff -u -r1.267 -r1.268 src/sys/netinet6/nd6.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->feedback
State-Changed-By: maya@NetBSD.org
State-Changed-When: Tue, 21 Apr 2020 16:32:52 +0000
State-Changed-Why:
Do you believe this fix is satisfactory?
State-Changed-From-To: feedback->closed
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Sun, 25 Jul 2021 02:47:54 +0000
State-Changed-Why:
feedback timeout, fixed a year ago
>Unformatted:
(Contact us)
$NetBSD: query-full-pr,v 1.46 2020/01/03 16:35:01 leot Exp $
$NetBSD: gnats_config.sh,v 1.9 2014/08/02 14:16:04 spz Exp $
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