Re: traceroute6: panic: pcb not read locked

On Aug 8, 2015 07:49, "Julien Charbon" <jch_at_freebsd.org> wrote:
>
> 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().

 I pushed a fix in r286443.  I am checking if other less common paths have
the same issue of kernel assertions being too strict with INP_INFO
read/write lock checks.

 Thanks for the detailed report and patch proposal.

--
Julien