The video device depends on the existence of its media device --- if there
is one. Acquire a reference to it.
Note that when the media device release callback is used, then the V4L2
device release callback is ignored and a warning is issued if both are
set.
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-dev.c | 51 ++++++++++++++++++++----------
1 file changed, 34 insertions(+), 17 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index d13954bd31fd..c1e4995eaf5c 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -176,6 +176,11 @@ static void v4l2_device_release(struct device *cd)
{
struct video_device *vdev = to_video_device(cd);
struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
+ bool v4l2_dev_has_release = v4l2_dev->release;
+#ifdef CONFIG_MEDIA_CONTROLLER
+ struct media_device *mdev = v4l2_dev->mdev;
+ bool mdev_has_release = mdev && mdev->ops && mdev->ops->release;
+#endif
mutex_lock(&videodev_lock);
if (WARN_ON(video_devices[vdev->minor] != vdev)) {
@@ -198,8 +203,8 @@ static void v4l2_device_release(struct device *cd)
mutex_unlock(&videodev_lock);
-#if defined(CONFIG_MEDIA_CONTROLLER)
- if (v4l2_dev->mdev && vdev->vfl_dir != VFL_DIR_M2M) {
+#ifdef CONFIG_MEDIA_CONTROLLER
+ if (mdev && vdev->vfl_dir != VFL_DIR_M2M) {
/* Remove interfaces and interface links */
media_devnode_remove(vdev->intf_devnode);
if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN)
@@ -207,23 +212,31 @@ static void v4l2_device_release(struct device *cd)
}
#endif
- /* Do not call v4l2_device_put if there is no release callback set.
- * Drivers that have no v4l2_device release callback might free the
- * v4l2_dev instance in the video_device release callback below, so we
- * must perform this check here.
- *
- * 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->release == NULL)
- v4l2_dev = NULL;
-
/* Release video_device and perform other
cleanups as needed. */
vdev->release(vdev);
- /* Decrease v4l2_device refcount */
- if (v4l2_dev)
+#ifdef CONFIG_MEDIA_CONTROLLER
+ if (mdev)
+ media_device_put(mdev);
+
+ /*
+ * Generally both struct media_device and struct v4l2_device are
+ * embedded in the same driver's context struct so having a release
+ * callback in both is a bug.
+ */
+ WARN_ON(v4l2_dev_has_release && mdev_has_release);
+#endif
+
+ /*
+ * Decrease v4l2_device refcount, but only if the media device doesn't
+ * have a release callback.
+ */
+ if (v4l2_dev_has_release
+#ifdef CONFIG_MEDIA_CONTROLLER
+ && !mdev_has_release
+#endif
+ )
v4l2_device_put(v4l2_dev);
}
@@ -792,11 +805,14 @@ static int video_register_media_controller(struct video_device *vdev)
u32 intf_type;
int ret;
- /* Memory-to-memory devices are more complex and use
+ /*
+ * Memory-to-memory devices are more complex and use
* their own function to register its mc entities.
*/
- if (!vdev->v4l2_dev->mdev || vdev->vfl_dir == VFL_DIR_M2M)
+ if (!vdev->v4l2_dev->mdev || vdev->vfl_dir == VFL_DIR_M2M) {
+ media_device_get(vdev->v4l2_dev->mdev);
return 0;
+ }
vdev->entity.obj_type = MEDIA_ENTITY_TYPE_VIDEO_DEVICE;
vdev->entity.function = MEDIA_ENT_F_UNKNOWN;
@@ -875,6 +891,7 @@ static int video_register_media_controller(struct video_device *vdev)
/* FIXME: how to create the other interface links? */
+ media_device_get(vdev->v4l2_dev->mdev);
#endif
return 0;
}
--
2.39.2
