linux-kernel - Re: [PATCH] Input: pwm-beeper - fix: scheduling while atomic

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Date:	Fri, 27 May 2016 10:54:52 +0200
From:	Manfred Schlaegl <manfred.schlaegl@....at>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Thierry Reding <thierry.reding@...il.com>,
	Manfred Schlaegl <manfred.schlaegl@...zinger.com>,
	Luis de Bethencourt <luis@...ethencourt.com>,
	Olivier Sobrie <olivier@...rie.be>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] Input: pwm-beeper - fix: scheduling while atomic

On 2016-05-26 02:36, Dmitry Torokhov wrote:
> On Tue, May 24, 2016 at 10:32:53AM +0200, Manfred Schlaegl wrote:
>> On 2016-05-20 18:59, Dmitry Torokhov wrote:
>>> Hi Manfred,
>>>
>>> On Wed, May 18, 2016 at 05:16:49PM +0200, Manfred Schlaegl wrote:
>>>> @@ -133,6 +149,8 @@ static int pwm_beeper_remove(struct platform_device *pdev)
>>>>  {
>>>>  	struct pwm_beeper *beeper = platform_get_drvdata(pdev);
>>>>  
>>>> +	cancel_work_sync(&beeper->work);
>>>> +
>>>>  	input_unregister_device(beeper->input);
>>>
>>> This is racy, request to play may come in after cancel_work_sync()
>>> returns but before we unregistered input device. I think you want the
>>> version below.
>>>
>>
>> Hi Dmitry,
>>
>> yes you are right. Thank you for your feedback.
>> I also see that point, but I think it would be a simpler change just
>> to cancel the worker after unregistering the device (to reorder 
>> cancel_work_sync and input_unregister_device).
> 
> That is an option, but I wanter to have close() because I also want to
> convert the driver to used devm for allocating resources, and then we'd
> need close() anyway so that we can get rid of remove() method.
> 
> Thanks.
> 

Ok. Thanks for clarification.
I will send a patch with the modifications you suggested before.

The following patch will also have some slight modifications in line numbers to make it apply after
cfae56f18 (input: misc: pwm-beeper: Explicitly apply PWM config extracted from pwm_args).

best regards,
Manfred