Re: Linux 4.2-rc1

From: Shuah Khan
Date: Thu Jul 09 2015 - 09:44:15 EST


On 07/09/2015 07:10 AM, Shuah Khan wrote:
> On 07/08/2015 09:17 PM, Linus Torvalds wrote:
>> On Wed, Jul 8, 2015 at 5:58 PM, Ming Lei <ming.lei@xxxxxxxxxxxxx> wrote:
>>> On Thu, Jul 9, 2015 at 1:29 AM, Linus Torvalds
>>> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>>> Also, it looks like you need to hold the "fw_lock" to even look at
>>>> that pointer, since the buffer can get reallocated etc.
>>>
>>> Yes, the above code with holding 'fw_lock' is right fix for the issue since
>>> sysfs read can happen anytime, and there is one race between firmware
>>> request abort and reading uevent of sysfs.
>>
>> So if fw_priv->buf is NULL, what should we do?
>>
>> Should we skip the TIMEOUT= and ASYNC= fields too?
>>
>> Something like the attached, perhaps?
>>
>> Shuah, how reproducible is this? Does this (completely untested) patch
>> make any difference?
>>
>
> Happened both times I booted 4.2-rc1 up, so I would say 100% so far.
> I will test with your patch and report results.
>

Yes. This patch fixed the problem. I have been seeing another problem
that both poweroff and reboot hang. I will get more data on this later
on today.

thanks,
-- Shuah
--
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@xxxxxxxxxxxxxxx | (970) 217-8978
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