[PATCH 0/1] iwlwifi: trace debug messages

[Luis Henriques]

On Tue, Sep 04, 2012 at 12:04:59PM +0100, Andy Whitcroft wrote:
> On Mon, Sep 03, 2012 at 01:52:44PM +0100, Luis Henriques wrote:
> 
> > It looks like the issue is due to an overflow of debug messages to the
> > kernel logs.  After bisecting the kernel, commit:
> > 
> > 2655e314c4b204966008689eaf3e87ba1f38d55c iwlwifi: trace debug messages
> > 
> > does fix the problem.  This commit had to be backported to the Precise
> > kernel as it didn't applied cleanly.  The original bug reporter claims
> > the issue is fixed with this backport.
> 
> This is rather a large patch which must fix the issue as a side effect
> rather than really fixing the original issue.  I am not against fixing
> this this way I guess, but it does feel a little heavy handed.  Did we
> have any idea which debug message was triggering the crash?

I understand your concerns and its ok for me to look for a different
solution.

I was able to reproduce the issue with a similar HW, and the last
message I'm able to get is:

iwlwifi 0000:0c:00.0: Invalid tbl->lq_type 0

Note that I get this message *before* the system actually freezes.
After a few seconds, I'm not able to get anything out of the system, and
a reboot will not show anything else on the logs.

I guess that I could spend some more time debugging it, but the solution
would probably end up being a SAUCE patch instead of a
cherry-pick/backport.  I simply bisected the kernel and this was the
commit that fixed it.

Another issue with this approach is that there is code brought in by this
commit that is not used on the driver (e.g., the IWL_DEBUG_QUIET_RFKILL
is introduced by this patch, but the 3.2 driver is not using it).
Having dead code (even if it isn't compiled in this example) always
brings maintenance issues...

Anyway, I'm ok dropping this patch and spend some more time debugging
it.

Cheers,
--
Luis