[media] uvcvideo: Move mutex lock/unlock inside uvc_free_buffers

Callers outside uvc_queue.c should not be forced to lock/unlock the
queue mutex manually. Move the mutex operations inside
uvc_free_buffers().

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/uvc/uvc_queue.c

@@ -89,6 +89,39 @@ void uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
 	queue->type = type;
 }
 
+/*
+ * Free the video buffers.
+ *
+ * This function must be called with the queue lock held.
+ */
+static int __uvc_free_buffers(struct uvc_video_queue *queue)
+{
+	unsigned int i;
+
+	for (i = 0; i < queue->count; ++i) {
+		if (queue->buffer[i].vma_use_count != 0)
+			return -EBUSY;
+	}
+
+	if (queue->count) {
+		vfree(queue->mem);
+		queue->count = 0;
+	}
+
+	return 0;
+}
+
+int uvc_free_buffers(struct uvc_video_queue *queue)
+{
+	int ret;
+
+	mutex_lock(&queue->mutex);
+	ret = __uvc_free_buffers(queue);
+	mutex_unlock(&queue->mutex);
+
+	return ret;
+}
+
 /*
  * Allocate the video buffers.
  *
@@ -110,7 +143,7 @@ int uvc_alloc_buffers(struct uvc_video_queue *queue, unsigned int nbuffers,
 
 	mutex_lock(&queue->mutex);
 
-	if ((ret = uvc_free_buffers(queue)) < 0)
+	if ((ret = __uvc_free_buffers(queue)) < 0)
 		goto done;
 
 	/* Bail out if no buffers should be allocated. */
@@ -151,28 +184,6 @@ int uvc_alloc_buffers(struct uvc_video_queue *queue, unsigned int nbuffers,
 	return ret;
 }
 
-/*
- * Free the video buffers.
- *
- * This function must be called with the queue lock held.
- */
-int uvc_free_buffers(struct uvc_video_queue *queue)
-{
-	unsigned int i;
-
-	for (i = 0; i < queue->count; ++i) {
-		if (queue->buffer[i].vma_use_count != 0)
-			return -EBUSY;
-	}
-
-	if (queue->count) {
-		vfree(queue->mem);
-		queue->count = 0;
-	}
-
-	return 0;
-}
-
 /*
  * Check if buffers have been allocated.
  */

drivers/media/video/uvc/uvc_v4l2.c

@@ -494,11 +494,9 @@ static int uvc_v4l2_release(struct file *file)
 	if (uvc_has_privileges(handle)) {
 		uvc_video_enable(stream, 0);
 
-		mutex_lock(&stream->queue.mutex);
 		if (uvc_free_buffers(&stream->queue) < 0)
 			uvc_printk(KERN_ERR, "uvc_v4l2_release: Unable to "
 					"free buffers.\n");
-		mutex_unlock(&stream->queue.mutex);
 	}
 
 	/* Release the file handle. */