[ath9k-devel] [PATCH] mac80211: debugfs var for the default aggregation timeout.

On Fri, Apr 8, 2016 at 4:31 AM, Avery Pennarun <[email protected]> wrote:
> On Fri, Apr 8, 2016 at 3:15 AM, Johannes Berg <[email protected]> wrote:
>> On Fri, 2016-04-08 at 09:01 +0200, Johannes Berg wrote:
>>> On Fri, 2016-04-08 at 08:56 +0200, Johannes Berg wrote:
>>> > On Thu, 2016-04-07 at 21:32 -0400, Avery Pennarun wrote:
>>> > > Yes.  Here it is:
>>> > > http://apenwarr.ca/tmp/mac80211-agg-status-crash.ko
>>> > >
>>> > Unfortunately there are no debug symbols in this file, so it
>>> > doesn't
>>> > help me much. I can't even seem to get objdump to disassemble it
>>> > correctly: looks like the file is in thumb, going from things
>>> > like R_ARM_THM_CALL relocations, but even -Mforce-thumb doesn't
>>> > seem
>>> > to DRT; sta_agg_status_read+0xeb isn't even a valid instruction
>>> > offset in regular ARM mode.
>>> >
>>> It *seems* that it most likely crashes on the first access to tid_tx,
>>> which is consistent with the story of disabling TX aggregation
>>> timeouts
>>> reducing the chances.
>>>
>>> So I guess we have to look for some TX aggregation teardown RCU
>>> pointer problem?
>>
>> Can't find anything. The only other thing I saw now is that the TID
>> appears to be 7 (in r7), might be worth looking for whether that's a
>> common thing or not?
>
> Just to be clear, this crash is only from *reading* the agg_status
> files.  I don't know if the crashiness reduces when disabling the
> aggregation timeouts, since that's a separate bug (in which the queue
> gets stuck and the 'pending' column of this file just keeps
> increasing).
>
> I'll try twiddling some options again tomorrow and see if I can get
> one with proper debug symbols.  For what it's worth, this platform is
> "ARMv7 Processor rev 1 (v7l)" and the gcc build is made for Cortex A9.
> You can find an x86 build of our toolchain in the git repo at
> https://gfiber.googlesource.com/toolchains/mindspeed.

Updated .ko file that definitely has debug symbols this time:
http://apenwarr.ca/tmp/mac80211-agg-status-crash-debugsyms.ko
a gdb compiled for x86-64 that can definitely read the above .ko file:
http://apenwarr.ca/tmp/arm-gdb

Thanks!