[em][panic] recursed on non-recursive mutex em0

[Jack Vogel]

On Wed, May 21, 2008 at 12:11 PM, Neil Hoggarth <neil at hoggarth.me.uk> wrote:
> Hi Folks,
>
> I opened PR kern/122928 last month, describing my problems with Intel
> PRO/1000 MT adaptor on 7-STABLE, with v6.7.3 of the em driver: every
> so often the machine would get into a state where it would repeatedly
> watchdog timeout the em0 interface, and the interface would stop
> receiving packets.
>
> A few weeks ago I cvsupped a newer version of the 7-STABLE source
> tree, after v6.9.0 of the em driver was MFCed. Since I started running
> on the newer build watchdog timeouts appear to be followed by a system
> panic rather than the freezing up of the interface.  I have no hard
> evidence but it "feels like" the panics are happening under the same
> sort of circumstance that was previously triggering my watchdog
> problem (basically network activity combined with CPU load). A similar
> observation was made by Yani Karydis on the freebsd-stable mailing
> list earlier in the month:
>
> http://lists.freebsd.org/pipermail/freebsd-stable/2008-May/042311.html
>
> I've now got a serial console set up, and I'm running a kernel with
> DDB support compiled in. I managed to get the information below out of
> the most recent panic. Is anyone able to use this to debug the
> situation? What else might I try to gather useful information?

This is a helpful start, I'll stare at the code and see... sounds like some
rx lock design issue.

Thanks Neil,

Jack