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Date: Tue, 2 Jun 2015 07:20:05 +0200
Message-ID: <CA+BoTQnDUtpjTJ41xodmrx0eXUny-KBMyF8JiCgeMCUJXegzkg@mail.gmail.com> (sfid-20150602_072042_464866_68167BA7)
Subject: Re: system hang with backports-20150511/20150525
From: Michal Kazior <michal.kazior@tieto.com>
To: Marty Faltesek <mfaltesek@google.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>,
	Martin Faltesek <martin.faltesek@gmail.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
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Sender: linux-wireless-owner@vger.kernel.org

On 1 June 2015 at 21:42, Marty Faltesek <mfaltesek@google.com> wrote:
> I disabled IEEE80211_HW_SUPPORT_FAST_XMIT before, and still saw the
> hang. I repeated today to confirm.

Thanks for checking.


> I added the extra ath10k debug flags you requested, and it causes a
> system reset without any messages, very soon after the last hbeat
> timestamp. I've uploaded  log "crash.6.1.15.13.46" to
> http://tinyurl.com/dmesg-ftrace.

I guess serial console gave up which isn't really surprising :( Thanks
for checking anyway.


> Any advice on how to bisect when using backports?

Sure. Generally you'll need to do the bisect on your linux-next tree
which you use to generate backports:

 git clone git://git.kernel.org/pub/scm/linux/kernel/git/backports/backports.git
 git clone git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
 cd linux-next
 git bisect start
 git bisect good a3da0fb6
 git bisect bad f17107c
 # repeat:
 cd ../backports
 ./gentree.py --clean --git-revision HEAD ../linux-next ../backports-output/
 cd ../backports-output
 # configure, make, test
 cd ../linux-next
 git bisect <good|bad> # "good" if problem doesn't reproduce, "bad" if it does
 # goto repeat


Michał


>
> On Mon, Jun 1, 2015 at 4:27 AM, Michal Kazior <michal.kazior@tieto.com> wrote:
>> On 1 June 2015 at 09:13, Kalle Valo <kvalo@qca.qualcomm.com> wrote:
>>> Michal Kazior <michal.kazior@tieto.com> writes:
>>>
>>>> +ath10k list
>>>>
>>>> On 1 June 2015 at 03:37, Marty Faltesek <mfaltesek@google.com> wrote:
>>>>> Starting with backports-20150511, and continuing with
>>>>> backports-20150525, we see frequent system hangs. backports-20150424
>>>>> had no issue.
>>>>
>>>> I don't see such binary releases on
>>>> https://backports.wiki.kernel.org/index.php/Main_Page
>>>> Hence I don't know what kernel you've backported the drivers from and
>>>> I can't compare anything.
>>>>
>>>> Can you provide more details, please?
>>>
>>> I suspect it's from here:
>>>
>>> https://www.kernel.org/pub/linux/kernel/projects/backports/2015/05/25/
>>>
>>> The backports project pages are a bit confusing and that location is
>>> hard to find.
>>
>> Oh, thanks!
>>
>> Hmm.. There was a ton of changes between 20150424 and 20150511. For
>> one, ath10k started to use chanctx API and FAST_XMIT. But it's not a
>> given these two are to blame.
>>
>> The latter can be easily disabled by removing
>> IEEE80211_HW_SUPPORT_FAST_XMIT from ar->hw->flags in ath10k's mac.c.
>> The former.. not so easy. I'd be awesome if you could do a git bisect.
>> The commit ids are a3da0fb6(good) f17107c(bad) (you need linux-next
>> git repo including its tags for these ids to be resolvable).
>>
>>
>> Michał