Date: Thu, 30 Apr 2009 14:48:40 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Simon Arlott <simon@fire.lp0.eu>
Cc: linux-kernel@vger.kernel.org, mchehab@infradead.org,
       linux-media@vger.kernel.org
Subject: Re: [PATCH] dvb-core: Fix potential mutex_unlock without mutex_lock
 in dvb_dvr_read
Message-Id: <20090430144840.6605e564.akpm@linux-foundation.org>
In-Reply-To: <49FA1B2E.8030402@simon.arlott.org.uk>
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	<20090430131818.d8aded42.akpm@linux-foundation.org>
	<49FA1B2E.8030402@simon.arlott.org.uk>
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On Thu, 30 Apr 2009 22:42:06 +0100
Simon Arlott <simon@fire.lp0.eu> wrote:

> >> diff --git a/drivers/media/dvb/dvb-core/dmxdev.c b/drivers/media/dvb/dvb-core/dmxdev.c
> >> index c35fbb8..d6d098a 100644
> >> --- a/drivers/media/dvb/dvb-core/dmxdev.c
> >> +++ b/drivers/media/dvb/dvb-core/dmxdev.c
> >> @@ -247,7 +247,7 @@ static ssize_t dvb_dvr_read(struct file *file, char __user *buf, size_t count,
> >>  	int ret;
> >>  
> >>  	if (dmxdev->exit) {
> >> -		mutex_unlock(&dmxdev->mutex);
> >> +		//mutex_unlock(&dmxdev->mutex);
> >>  		return -ENODEV;
> >>  	}
> > 
> > Is there any value in retaining all the commented-out lock operations,
> > or can we zap 'em?
> 
> I'm assuming they should really be there - it's just not practical
> because the call to dvb_dmxdev_buffer_read is likely to block waiting
> for data.

well..  such infomation is much better communicated via a nice comment,
rather than mystery-dead-code?

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