Re: WARNING: at drivers/net/wireless/brcm80211/brcmsmac/main.c:7539

["Arend van Spriel" <arend@broadcom.com>]

On 01/02/2013 02:50 PM, Seth Forshee wrote:
> On Wed, Jan 02, 2013 at 01:05:49PM +0100, Arend van Spriel wrote:
>> On 12/28/2012 07:07 AM, Linus Torvalds wrote:
>>> Ok, maybe somebody is interested in this.. I don't know what triggered
>>> it, but maybe the few lines around it give some clue.
>>
>> Hi Linus,
>>
>> I am interested (being paid for it kinda helps). The warning itself does
>> not necessarily have to be a problem, but the frameid mismatch between
>> tx status info and the related buffer taken from the DMA ring does.
>> Smells like a race condition, but I need to investigate that.
>>
>>> I think it's new to 3.8-rc1, because I haven't seen it before (well,
>>> I'm running current -git - v3.8.0-rc1-00035-g101e5c7470eb to be exact
>>> - but the networking changes since -rc1 are small and seem unrelated).
>>> But maybe it just happens under certain circumstances.
>>
>> We had a big contribution from Canonical (cc-ed Seth) in brcmsmac
>> itself. Not playing the blame game, but I suspect it has altered
>> circumstances making the real issue (that was already there) more likely
>> to happen. Hope that helps us nailing it down.
> 
> I'm certain that both problems existed prior to 3.8-rc1. The warning
> itself has generated a fairly consistent trickle of bug reports for a
> while now. I haven't noticed any increased frequency of these messages;
> if anything I'd say I'm hitting the WARN_ON less often (though I've been
> doing a lot of testing under heavy load so my observations may not be
> typical).

Hi Seth,

Indeed the warning has been there for a while, but the fatal error
resulting in triggering a restart from mac80211 has popped up late in
the 3.7-rc cycles and seem to consistently fail on our smoketest as well.

> The channel mismatch errors are something I plan to look into, but I've
> been distracted by some background scanning problems (not specific to
> brcmsmac).

The channel mismatch could be related, but I do not have a clear picture
yet. Possibly your tracepoints will help with that. Keep you posted.

Gr. AvS