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media: v4l2-dev: lock req_queue_mutex

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We need to serialize streamon/off with queueing new requests.
These ioctls may trigger the cancellation of a streaming
operation, and that should not be mixed with queuing a new
request at the same time.

Finally close() needs this lock since that too can trigger the
cancellation of a streaming operation.

We take the req_queue_mutex here before any other locks since
it is a very high-level lock.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Hans Verkuil
2018-05-21 04:54:34 -04:00
committed by Mauro Carvalho Chehab
parent 93a9d9008d
commit cc6eddcd37
2 changed files with 37 additions and 3 deletions
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18
drivers/media/v4l2-core/v4l2-dev.c
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@@ -444,8 +444,22 @@ static int v4l2_release(struct inode *inode, struct file *filp)
struct video_device *vdev = video_devdata(filp);
int ret = 0;
if (vdev->fops->release)
ret = vdev->fops->release(filp);
/*
* We need to serialize the release() with queueing new requests.
* The release() may trigger the cancellation of a streaming
* operation, and that should not be mixed with queueing a new
* request at the same time.
*/
if (vdev->fops->release) {
if (v4l2_device_supports_requests(vdev->v4l2_dev)) {
mutex_lock(&vdev->v4l2_dev->mdev->req_queue_mutex);
ret = vdev->fops->release(filp);
mutex_unlock(&vdev->v4l2_dev->mdev->req_queue_mutex);
} else {
ret = vdev->fops->release(filp);
}
}
if (vdev->dev_debug & V4L2_DEV_DEBUG_FOP)
dprintk("%s: release\n",
video_device_node_name(vdev));