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

[Seth Forshee <seth.forshee@canonical.com>]

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).

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).

Seth