Re: Another AR5008 hang

[Ben Gamari <bgamari.foss@gmail.com>]

On Tue, 30 Mar 2010 06:14:40 -0700 (PDT), Ben Gamari <bgamari.foss@gmail.com> wrote:
> On Tue, 30 Mar 2010 08:03:06 +0200, Johannes Berg <johannes@sipsolutions.net> wrote:
> > On Mon, 2010-03-29 at 10:26 -0700, Ben Gamari wrote:
> > > New (2.6.33 and greater) kernels seem to result in a selective hang on my
> > > machine directly only seconds after association with an 802.11N access point
> > > (hosted with hostapd and another ar5008). I've included dmesg output for a
> > > failure event, including back traces of hung processes. What ath9k.debug flags
> > > would be most helpful for tracing this further?
> > 
> > None, I would think, this seems to be a lockup between
> > modprobe/stop_machine and some rtnl things, but I have no idea why that
> > would happen. Do you have lockdep enabled? And if you do, please disable
> > RCU lockdep as it typically gives you a warning and then turns off
> > lockdep...
> > 
> Thank you very much for your response. I do not currently have lockdep enabled,
> but I'm building a new kernel as we speak. Thanks again,
> 
Well, it will take me a bit longer than expected to get lockdep results on
2.6.34 due to a recent change[1] in how sysfs attributes are exposed to
lockdep. Hopefully this will be fixed soon.

That being said, after discovering this I went back and recompiled with
lockdep. Unfortunately, I'm now having trouble reproducing the issue on this
release. I still can with 2.6.34-rc1 though, so, again, hopefully soon I'll be
able to say where the deadlock occurs. I'll let you know as soon as I have
news. Thanks for your help,

- Ben

[1] http://lkml.org/lkml/2010/3/8/365