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

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Message-ID: <20160526003615.GE22369@dtor-ws>
Date:	Wed, 25 May 2016 17:36:15 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Manfred Schlaegl <manfred.schlaegl@....at>
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 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.

-- 
Dmitry