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From: Andrew Chant <andrew.chant@gmail.com>
Date: Mon, 16 Jul 2012 20:06:56 -0700
Message-ID: <CANugF35nYYToPfPm7pg_bQhBgwdSwusbkTokDhVxZkB+Xggvvw@mail.gmail.com> (sfid-20120717_050743_353409_94754125)
Subject: Re: v3.4.4 ath9k: kernel NULL pointer dereference in skb_dequeue
 during heavy udp xmit
To: Mohammed Shafi <shafi.wireless@gmail.com>
Cc: linux-wireless@vger.kernel.org,
	"Luis R. Rodriguez" <mcgrof@gmail.com>,
	Jouni Malinen <jouni@qca.qualcomm.com>,
	Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>,
	Senthil Balasubramanian <senthilb@qca.qualcomm.com>
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-wireless-owner@vger.kernel.org

Thanks.  That patch seems good against 3.4.4 after the first few
minutes - I'll leave it to run overnight.

On Sun, Jul 15, 2012 at 10:19 PM, Mohammed Shafi
<shafi.wireless@gmail.com> wrote:
> On Thu, Jul 12, 2012 at 12:05 PM, Andrew Chant <andrew.chant@gmail.com> wrote:
>> Any QCA people get a chance to take a look?  This is completely
>> reproducible for me on 3.4.4, sometimes within a few minutes but
>> occasionally requires up to an hour.  Do you qca folks have any tests
>> where you continuously transmit as many UDP packets as you possibly
>> can to another host?
>
> please check whether the following patch helps.
> http://comments.gmane.org/gmane.linux.kernel.wireless.general/93723
> Could please help whether it happens with wireless-testing tree ?
> http://linuxwireless.org/en/developers/Documentation/git-guide#Cloning_latest_wireless-testing
>
>>
>> On Fri, Jul 6, 2012 at 12:46 AM, Andrew Chant <andrew.chant@gmail.com> wrote:
>>> I was able to reproduce this on a boot shortly afterwards without
>>> changing the frequencies.
>>> Exact same stack trace w/ exception of slightly different values for
>>> RBX & R15, and R10 had 0x7f instead of 0x80.  I have not been able to
>>> reproduce since despite trying quite hard :)  I have a picture of the
>>> second oops if that helps.
>>> PCI ID is 168c:0030 (AR9300 Wireless LAN adaptor (rev 01))
>>> -Andrew
>>>
>>> On Fri, Jul 6, 2012 at 12:15 AM, Johannes Berg
>>> <johannes@sipsolutions.net> wrote:
>>>> -John
>>>> +QCA folks
>>>>
>>>> On Thu, 2012-07-05 at 21:36 -0700, Andrew Chant wrote:
>>>>
>>>>>  while performance testing ath9k -> ath9k performance in 3.4.4, I got
>>>>> a nasty kernel panic.  My performance testing involved filling the air
>>>>> with 1410-byte UDP packets between the machines, and switching the
>>>>> frequencies of the two cards to see how frequency affected
>>>>> performance.  I had switched between channels 36, 40, 44, and 48.
>>>>> Oops was on the transmitting machine, which was acting as the AP.
>>>>>
>>>>> Very clear screen image of the oops is at
>>>>> https://picasaweb.google.com/lh/photo/CjBdHLZH0up5PrnmCySJidMTjNZETYmyPJy0liipFm0?feat=directlink
>>>>
>>>> I briefly looked at this, but I don't see a bug in mac80211. It seems
>>>> likely that ath9k hands back a corrupted SKB, or frees one it no longer
>>>> owns, or such. The skb->next/prev pointers seem corrupted (rcx is NULL)
>>>> in one of the SKBs on the list, but mac80211 can't do that afaict.
>>>>
>>>> johannes
>>>>
>> --
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>
>
>
> --
> thanks,
> shafi