Re: WARNING: at drivers/net/wireless/ath/ath9k/recv.c:536 ath_stoprecv+0xc8/0xda[ath9k]()

[Ben Greear]

On 03/08/2011 11:45 AM, Brian Prodoehl wrote:
> On Tue, Mar 8, 2011 at 2:27 PM, Ben Greear<greearb@xxxxxxxxxxxxxxx>  wrote:
> > On 03/08/2011 10:49 AM, Justin P. Mattock wrote:
> > > On 03/07/2011 07:22 AM, Mohammed Shafi wrote:
> > > > On Mon, Mar 7, 2011 at 8:42 PM, John W.
> > > > Linville<linville@xxxxxxxxxxxxx>  wrote:
> > > > > On Sun, Mar 06, 2011 at 12:47:05AM -0800, Justin Mattock wrote:
> > > > >
> > > > > > full dmesg here:
> > > > > > http://fpaste.org/5JQp/
> > > > > > let me know if I need to supply any info(also I can try a bisect, but
> > > > > > am in the middle of changing residencies, so it might not be right
> > > > > > away)
> > > > >
> > > > > One of the Atheros guys suggested that you change a DMA timeout value.
> > > > > Did you try that?
> > > >
> > > > John it looks like increasing the timeout also does not seems to help.
> > > > A user reported this issue in ath9k developer list and he told that
> > > > increasing the timeout did not fix this issue.
> > > >
> > > > > John
> > > > > --
> > > > > John W. Linville Someday the world will need a hero, and you
> > > > > linville@xxxxxxxxxxxxx might be all we have. Be ready.
> > > > > --
> > > > > To unsubscribe from this list: send the line "unsubscribe
> > > > > linux-wireless" in
> > > > > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > >
> > > at barnes and noble, and I see this has fired off again. will see if I
> > > can reproduce and bisect.
> >
> > This problem goes way back, and the driver has had lots of fixes in the
> > last few months, so I'm not sure if bisecting is going to
> > do you any good.
> >
> > Thanks,
> > Ben
>
> The warnings have been around since you added the check for the
> problem, right?  I remember initially it was a WARN_ON, and I'd get a
> steady flood of backtraces, and then it was switched to a
> WARN_ON_ONCE.  I see these on every platform I have (x86_64, IXP425
> and AR71xx) with AR9002 and AR9003.

I don't think I added the original check, but either way, it's
an old problem and bisecting it is unlikely to help.

I can't believe that the Atheros guys really are unable reproduce
this, but I can believe that it might be very difficult to
actually understand and fix.

At least in my testing, I see it quite often, but it doesn't
seem to cause any serious harm.  We do occasionally see crashes,
especially on module unload for a heavily utilized system, or
one that is constantly trying and failing to associate,
so it could be related to this.

Also, my patches to decrease scan and work_work related channel changes
made this harder to hit for our test cases.

Thanks,
Ben

--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com

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