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-rw-r--r--drivers/media/v4l2-core/v4l2-dev.c34
1 files changed, 14 insertions, 20 deletions
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index 33617c3..9aa530a 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -194,7 +194,7 @@ static void v4l2_device_release(struct device *cd)
mutex_unlock(&videodev_lock);
#if defined(CONFIG_MEDIA_CONTROLLER)
- if (v4l2_dev && v4l2_dev->mdev &&
+ if (v4l2_dev->mdev &&
vdev->vfl_type != VFL_TYPE_SUBDEV)
media_device_unregister_entity(&vdev->entity);
#endif
@@ -207,7 +207,7 @@ static void v4l2_device_release(struct device *cd)
* TODO: In the long run all drivers that use v4l2_device should use the
* v4l2_device release callback. This check will then be unnecessary.
*/
- if (v4l2_dev && v4l2_dev->release == NULL)
+ if (v4l2_dev->release == NULL)
v4l2_dev = NULL;
/* Release video_device and perform other
@@ -360,27 +360,22 @@ static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
* hack but it will have to do for those drivers that are not
* yet converted to use unlocked_ioctl.
*
- * There are two options: if the driver implements struct
- * v4l2_device, then the lock defined there is used to
- * serialize the ioctls. Otherwise the v4l2 core lock defined
- * below is used. This lock is really bad since it serializes
- * completely independent devices.
+ * All drivers implement struct v4l2_device, so we use the
+ * lock defined there to serialize the ioctls.
*
- * Both variants suffer from the same problem: if the driver
- * sleeps, then it blocks all ioctls since the lock is still
- * held. This is very common for VIDIOC_DQBUF since that
- * normally waits for a frame to arrive. As a result any other
- * ioctl calls will proceed very, very slowly since each call
- * will have to wait for the VIDIOC_QBUF to finish. Things that
- * should take 0.01s may now take 10-20 seconds.
+ * However, if the driver sleeps, then it blocks all ioctls
+ * since the lock is still held. This is very common for
+ * VIDIOC_DQBUF since that normally waits for a frame to arrive.
+ * As a result any other ioctl calls will proceed very, very
+ * slowly since each call will have to wait for the VIDIOC_QBUF
+ * to finish. Things that should take 0.01s may now take 10-20
+ * seconds.
*
* The workaround is to *not* take the lock for VIDIOC_DQBUF.
* This actually works OK for videobuf-based drivers, since
* videobuf will take its own internal lock.
*/
- static DEFINE_MUTEX(v4l2_ioctl_mutex);
- struct mutex *m = vdev->v4l2_dev ?
- &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;
+ struct mutex *m = &vdev->v4l2_dev->ioctl_lock;
if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
return -ERESTARTSYS;
@@ -938,12 +933,11 @@ int __video_register_device(struct video_device *vdev, int type, int nr,
name_base, nr, video_device_node_name(vdev));
/* Increase v4l2_device refcount */
- if (vdev->v4l2_dev)
- v4l2_device_get(vdev->v4l2_dev);
+ v4l2_device_get(vdev->v4l2_dev);
#if defined(CONFIG_MEDIA_CONTROLLER)
/* Part 5: Register the entity. */
- if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
+ if (vdev->v4l2_dev->mdev &&
vdev->vfl_type != VFL_TYPE_SUBDEV) {
vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L;
vdev->entity.name = vdev->name;
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