Re: traceroute6: panic: pcb not read locked

From: Julien Charbon <jch_at_freebsd.org>
Date: Sat, 08 Aug 2015 07:49:38 +0200
On 08/08/15 05:25, Mark Johnston wrote:
> On Fri, Aug 07, 2015 at 08:04:01PM -0500, Larry Rosenman wrote:
>> Trying to debug TimeWarner IPV6 to my HE.NET tunnel, and running traceroute6, 
>> got the following panic:
>>
>> borg.lerctr.org dumped core - see /var/crash/vmcore.0
>>
>> Fri Aug  7 19:58:40 CDT 2015
>>
>> FreeBSD borg.lerctr.org 11.0-CURRENT FreeBSD 11.0-CURRENT #32 r286338: Wed Aug  5 15:57:55 CDT 2015     root_at_borg.lerctr.org:/usr/obj/usr/src/sys/VT-LER  amd64
>>
>> panic: Lock tcp not read locked _at_ /usr/src/sys/netinet/tcp_subr.c:1189
>>
>> GNU gdb 6.1.1 [FreeBSD]
>> Copyright 2004 Free Software Foundation, Inc.
>> GDB is free software, covered by the GNU General Public License, and you are
>> welcome to change it and/or distribute copies of it under certain conditions.
>> Type "show copying" to see the conditions.
>> There is absolutely no warranty for GDB.  Type "show warranty" for details.
>> This GDB was configured as "amd64-marcel-freebsd"...
>>
>> Unread portion of the kernel message buffer:
>> panic: Lock tcp not read locked _at_ /usr/src/sys/netinet/tcp_subr.c:1189
> 
> This appears to be fallout from r286227: the tcpinfo lock assertion in
> tcp_notify() is too strong, since tcp_notify() can still be called from
> c with the tcpinfo write lock held.

 Nice catch, I agree these tcpinfo lock assertion are too strong.  I am
fixing and testing that as in top of tcp_notify() and tcp_drop(), you
also need to update also tcp_close() and tcp_detach().

 By the way I am working on make INP_INFO_WLOCK a INP_INFO_RLOCK in
in6_pcbnotify() but this is not for today.

 Thanks.

--
Julien


Received on Sat Aug 08 2015 - 03:49:54 UTC

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