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From: Avery Pennarun <apenwarr@gmail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: ath9k-devel <ath9k-devel@lists.ath9k.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH] mac80211: debugfs var for the default aggregation timeout.
Date: Fri, 8 Apr 2016 04:31:45 -0400	[thread overview]
Message-ID: <CAHqTa-1SO+asqf7Fn2d+J_w8vvJ1CnnMG8AGB2O1CBjeaaL8hA@mail.gmail.com> (raw)
In-Reply-To: <1460099746.30678.3.camel@sipsolutions.net>

On Fri, Apr 8, 2016 at 3:15 AM, Johannes Berg <johannes@sipsolutions.net> 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.

Thanks for looking into it :)

Avery

WARNING: multiple messages have this Message-ID (diff)
From: Avery Pennarun <apenwarr@gmail.com>
To: ath9k-devel@lists.ath9k.org
Subject: [ath9k-devel] [PATCH] mac80211: debugfs var for the default aggregation timeout.
Date: Fri, 8 Apr 2016 04:31:45 -0400	[thread overview]
Message-ID: <CAHqTa-1SO+asqf7Fn2d+J_w8vvJ1CnnMG8AGB2O1CBjeaaL8hA@mail.gmail.com> (raw)
In-Reply-To: <1460099746.30678.3.camel@sipsolutions.net>

On Fri, Apr 8, 2016 at 3:15 AM, Johannes Berg <johannes@sipsolutions.net> 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.

Thanks for looking into it :)

Avery

  reply	other threads:[~2016-04-08  8:32 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-04  5:03 ath9k(?): AP stops sending traffic to iPhone 4S until another 802.11n-capable STA joins Avery Pennarun
2016-02-16 21:28 ` Avery Pennarun
2016-02-16 21:28   ` [PATCH] mac80211: debugfs var for the default aggregation timeout Avery Pennarun
2016-02-16 21:44     ` Johannes Berg
2016-02-17  2:05     ` Sujith Manoharan
2016-02-23 10:14     ` Johannes Berg
2016-02-23 18:43       ` Avery Pennarun
2016-02-23 20:05         ` Johannes Berg
2016-04-05 23:46           ` Avery Pennarun
2016-04-05 23:46             ` [ath9k-devel] " Avery Pennarun
2016-04-06  7:40             ` Johannes Berg
2016-04-06  7:40               ` [ath9k-devel] " Johannes Berg
2016-04-08  1:32               ` Avery Pennarun
2016-04-08  1:32                 ` [ath9k-devel] " Avery Pennarun
2016-04-08  6:56                 ` Johannes Berg
2016-04-08  6:56                   ` [ath9k-devel] " Johannes Berg
2016-04-08  7:01                   ` Johannes Berg
2016-04-08  7:01                     ` [ath9k-devel] " Johannes Berg
2016-04-08  7:15                     ` Johannes Berg
2016-04-08  7:15                       ` [ath9k-devel] " Johannes Berg
2016-04-08  8:31                       ` Avery Pennarun [this message]
2016-04-08  8:31                         ` Avery Pennarun
2016-04-09  1:27                         ` Avery Pennarun
2016-04-09  1:27                           ` [ath9k-devel] " Avery Pennarun
2016-04-09  4:56                           ` Johannes Berg
2016-04-09  4:56                             ` [ath9k-devel] " Johannes Berg
2016-04-10  0:31                             ` Adrian Chadd
2016-04-10  0:31                               ` [ath9k-devel] " Adrian Chadd
2016-04-10  1:59                               ` bruce m beach
2016-04-10  2:12                                 ` [ath9k-devel] " bruce m beach
2016-04-19  1:29                                 ` Avery Pennarun
2016-04-19  1:29                                   ` [ath9k-devel] " Avery Pennarun
2016-02-16 22:05   ` ath9k(?): AP stops sending traffic to iPhone 4S until another 802.11n-capable STA joins Johannes Berg
2016-02-17  4:32     ` Avery Pennarun
2016-02-17  6:23       ` Krishna Chaitanya
2016-02-17  7:05         ` Avery Pennarun

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