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| author | Jonathan Nieder <jrnieder@gmail.com> | 2011-05-01 06:29:37 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2011-05-20 09:29:36 -0300 |
| commit | 1fe70e963028f34ba5e32488a7870ff4b410b19b (patch) | |
| tree | 8185ba45b69831b8cb6a1b1aef5cb84ea092b8cc /drivers/media/video/cx88/cx88-blackbird.c | |
| parent | 8a317a8760cfffa8185b56ff59fb4b6c58488d79 (diff) | |
| download | lwn-1fe70e963028f34ba5e32488a7870ff4b410b19b.tar.gz lwn-1fe70e963028f34ba5e32488a7870ff4b410b19b.zip | |
[media] cx88: fix locking of sub-driver operations
The BKL conversion of this driver seems to have gone wrong.
Loading the cx88-blackbird driver deadlocks.
The cause: mpeg_ops::open in the cx2388x blackbird driver acquires the
device lock and calls the sub-driver's request_acquire, which tries to
acquire the lock again. Fix it by clarifying the semantics of
request_acquire, request_release, advise_acquire, and advise_release:
now all will rely on the caller to acquire the device lock.
Based on work by Ben Hutchings <ben@decadent.org.uk>.
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=31962
Reported-by: Andi Huber <hobrom@gmx.at>
Tested-by: Andi Huber <hobrom@gmx.at>
Tested-by: Marlon de Boer <marlon@hyves.nl>
Cc: stable@kernel.org
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/video/cx88/cx88-blackbird.c')
| -rw-r--r-- | drivers/media/video/cx88/cx88-blackbird.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/media/video/cx88/cx88-blackbird.c b/drivers/media/video/cx88/cx88-blackbird.c index b93fbd39a39e..a6f7d53a4510 100644 --- a/drivers/media/video/cx88/cx88-blackbird.c +++ b/drivers/media/video/cx88/cx88-blackbird.c @@ -1125,13 +1125,13 @@ static int mpeg_release(struct file *file) /* Make sure we release the hardware */ drv = cx8802_get_driver(dev, CX88_MPEG_BLACKBIRD); - mutex_unlock(&dev->core->lock); - if (drv) drv->request_release(drv); atomic_dec(&dev->core->mpeg_users); + mutex_unlock(&dev->core->lock); + return 0; } |