linux-kernel - Re: [PATCH] [media] lmedm04: Do not unlock mutex if mutex_lock

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Date:	Sat, 16 Apr 2011 17:37:23 +0100
From:	Malcolm Priestley <tvboxspy@...il.com>
To:	Alexey Khoroshilov <khoroshilov@...ras.ru>
Cc:	Mauro Carvalho Chehab <mchehab@...radead.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [media] lmedm04: Do not unlock mutex if
 mutex_lock_interruptible failed

On Sat, 2011-04-16 at 01:01 +0100, Malcolm Priestley wrote:
> On Sat, 2011-04-16 at 00:40 +0400, Alexey Khoroshilov wrote:
> > There are a couple of places where mutex_unlock() is called even 
> > if mutex_lock_interruptible() failed. The patch fixes the issue.
> > 
> > Found by Linux Driver Verification project (linuxtesting.org).
> > 
> > Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
> > ---
> >  drivers/media/dvb/dvb-usb/lmedm04.c |   12 +++++++-----
> >  1 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/media/dvb/dvb-usb/lmedm04.c b/drivers/media/dvb/dvb-usb/lmedm04.c
> > index f2db012..40907df 100644
> > --- a/drivers/media/dvb/dvb-usb/lmedm04.c
> > +++ b/drivers/media/dvb/dvb-usb/lmedm04.c
> > @@ -591,9 +591,10 @@ static int lme2510_streaming_ctrl(struct dvb_usb_adapter *adap, int onoff)
> >  	else {
> >  		deb_info(1, "STM Steam Off");
> >  		/* mutex is here only to avoid collision with I2C */
> > -		ret = mutex_lock_interruptible(&adap->dev->i2c_mutex);
> > +		if (mutex_lock_interruptible(&adap->dev->i2c_mutex) < 0)
> > +			return -EAGAIN;
> >  
> > -		ret |= lme2510_usb_talk(adap->dev, clear_reg_3,
> > +		ret = lme2510_usb_talk(adap->dev, clear_reg_3,
> >  				sizeof(clear_reg_3), rbuf, rlen);
> >  		st->stream_on = 0;
> >  		st->i2c_talk_onoff = 1;
> 
> Unfortunately dvb-usb does not provide -EAGAIN on streaming_ctrl
> stopping and returns 0 instead.
> 

I have added a patch to dvb-usb to return device errors to the demuxer

This patch may now be applied.

Tested by: Malcolm Priestley <tvboxspy@...il.com>

Regards

Malcolm


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