Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso...

[cascardo/linux.git] / drivers / media / v4l2-core / v4l2-dev.c

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index 33617c3..9aa530a 100644 (file)
--- 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;