lkml.org 
[lkml]   [2008]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] Fix open/close race in saa7134
    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



    \
     
     \ /
      Last update: 2008-06-22 19:37    [W:2.654 / U:0.160 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site