Messages in this thread | | | Date | Sun, 22 Jun 2008 19:33:37 +0200 | From | Marcin Slusarz <> | Subject | Re: [PATCH] Fix open/close race in saa7134 |
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On Sun, Jun 22, 2008 at 10:05:07AM -0700, Arjan van de Ven wrote: > > From: Arjan van de Ven <arjan@linux.intel.com> > Date: Sun, 22 Jun 2008 10:03:02 -0700 > Subject: [PATCH] Fix open/close race in saa7134 > > The saa7134 driver uses a (non-atomic) variable in an attempt to > only allow one opener of the device (how it deals with sending > the fd over unix sockets I don't know). > > Unfortunately, the release function first decrements this variable, > and THEN goes on to disable more of the device. This allows for > a race where another opener of the device comes in after the decrement of > the variable, configures the hardware just to then see the hardware > be disabled by the rest of the release function.
Simplier fix: http://lkml.org/lkml/2008/6/9/308 But I don't remember whether it was applied or not...
> > This patch makes the release function use the same lock as the open > function to protect the hardware as well as the variable (which now > at least has some locking to protect it). > > Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> > --- > drivers/media/video/saa7134/saa7134-empress.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/drivers/media/video/saa7134/saa7134-empress.c b/drivers/media/video/saa7134/saa7134-empress.c > index 81431ee..9108843 100644 > --- a/drivers/media/video/saa7134/saa7134-empress.c > +++ b/drivers/media/video/saa7134/saa7134-empress.c > @@ -110,6 +110,8 @@ static int ts_release(struct inode *inode, struct file *file) > { > struct saa7134_dev *dev = file->private_data; > > + mutex_lock(&dev->empress_tsq.vb_lock); > + > videobuf_stop(&dev->empress_tsq); > videobuf_mmap_free(&dev->empress_tsq); > dev->empress_users--; > @@ -121,6 +123,8 @@ static int ts_release(struct inode *inode, struct file *file) > saa_writeb(SAA7134_AUDIO_MUTE_CTRL, > saa_readb(SAA7134_AUDIO_MUTE_CTRL) | (1 << 6)); > > + mutex_unlock(&dev->empress_tsq.vb_lock); > + > return 0; > } > > -- > 1.5.5.1
PS: I can't access 2.6.25 oopses anymore (timeout). Can you fix it? http://kerneloops.org/version.php?start=1671168&end=1703935&version=25-release&count=4509
Marcin
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