[media] cx88: hold device lock during sub-driver initialization

cx8802_blackbird_probe makes a device node for the mpeg sub-device
before it has been added to dev->drvlist.  If the device is opened
during that time, the open succeeds but request_acquire cannot be
called, so the reference count remains zero.  Later, when the device
is closed, the reference count becomes negative --- uh oh.

Close the race by holding core->lock during probe and not releasing
until the device is in drvlist and initialization finished.
Previously the BKL prevented this race.

Reported-by: Andreas 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>

1 files changed, 0 insertions, 2 deletions

diff --git a/drivers/media/video/cx88/cx88-blackbird.c b/drivers/media/video/cx88/cx88-blackbird.c
index a6f7d53..f637d34 100644
--- a/drivers/media/video/cx88/cx88-blackbird.c
+++ b/drivers/media/video/cx88/cx88-blackbird.c
@@ -1335,11 +1335,9 @@ static int cx8802_blackbird_probe(struct cx8802_driver *drv)
 	blackbird_register_video(dev);
 
 	/* initial device configuration: needed ? */
-	mutex_lock(&dev->core->lock);
 //	init_controls(core);
 	cx88_set_tvnorm(core,core->tvnorm);
 	cx88_video_mux(core,0);
-	mutex_unlock(&dev->core->lock);
 
 	return 0;