3 files changed, 37 insertions, 0 deletions

diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 6b1ef85d8cc8..1898099ec65a 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -143,6 +143,7 @@ static inline void video_put(struct video_device *vdev)
 static void v4l2_device_release(struct device *cd)
 {
         struct video_device *vdev = to_video_device(cd);
+        struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
 
         mutex_lock(&videodev_lock);
         if (video_device[vdev->minor] != vdev) {
@@ -169,6 +170,10 @@ static void v4l2_device_release(struct device *cd)
         /* Release video_device and perform other
            cleanups as needed. */
         vdev->release(vdev);
+
+        /* Decrease v4l2_device refcount */
+        if (v4l2_dev)
+                v4l2_device_put(v4l2_dev);
 }
 
 static struct class video_class = {
@@ -676,6 +681,11 @@ int __video_register_device(struct video_device *vdev, int type, int nr,
         if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
                 printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
                         name_base, nr, video_device_node_name(vdev));
+
+        /* Increase v4l2_device refcount */
+        if (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) {
diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index fd7a445ce34c..5aeaf876ba9b 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -37,6 +37,7 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
         spin_lock_init(&v4l2_dev->lock);
         mutex_init(&v4l2_dev->ioctl_lock);
         v4l2_prio_init(&v4l2_dev->prio);
+        kref_init(&v4l2_dev->ref);
         v4l2_dev->dev = dev;
         if (dev == NULL) {
                 /* If dev == NULL, then name must be filled in by the caller */
@@ -54,6 +55,21 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register);
 
+static void v4l2_device_release(struct kref *ref)
+{
+        struct v4l2_device *v4l2_dev =
+                container_of(ref, struct v4l2_device, ref);
+
+        if (v4l2_dev->release)
+                v4l2_dev->release(v4l2_dev);
+}
+
+int v4l2_device_put(struct v4l2_device *v4l2_dev)
+{
+        return kref_put(&v4l2_dev->ref, v4l2_device_release);
+}
+EXPORT_SYMBOL_GPL(v4l2_device_put);
+
 int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
                                                 atomic_t *instance)
 {
diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index 3b723283da26..bd102cf509ac 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -60,8 +60,19 @@ struct v4l2_device {
         struct v4l2_prio_state prio;
         /* BKL replacement mutex. Temporary solution only. */
         struct mutex ioctl_lock;
+        /* Keep track of the references to this struct. */
+        struct kref ref;
+        /* Release function that is called when the ref count goes to 0. */
+        void (*release)(struct v4l2_device *v4l2_dev);
 };
 
+static inline void v4l2_device_get(struct v4l2_device *v4l2_dev)
+{
+        kref_get(&v4l2_dev->ref);
+}
+
+int v4l2_device_put(struct v4l2_device *v4l2_dev);
+
 /* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev.
    dev may be NULL in rare cases (ISA devices). In that case you
    must fill in the v4l2_dev->name field before calling this function. */