media: uvcvideo: Handle locks in uvc_queue_return_buffers

Most of the calls to uvc_queue_return_buffers() wrap the call with
spin_lock_irq()/spin_unlock_irq().

Rename uvc_queue_return_buffers to __uvc_queue_return_buffers to
indicate that this is the version that does not handle locks and create
a new version of the function that handles the lock.

Reviewed-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Link: https://lore.kernel.org/r/20250616-uvc-fop-v4-2-250286570ee7@chromium.org
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

Author: ribalda

drivers/media/usb/uvc/uvc_queue.c

@@ -42,13 +42,15 @@ static inline struct uvc_buffer *uvc_vbuf_to_buffer(struct vb2_v4l2_buffer *buf)
  *
  * This function must be called with the queue spinlock held.
  */
-static void uvc_queue_return_buffers(struct uvc_video_queue *queue,
-			       enum uvc_buffer_state state)
+static void __uvc_queue_return_buffers(struct uvc_video_queue *queue,
+				       enum uvc_buffer_state state)
 {
 	enum vb2_buffer_state vb2_state = state == UVC_BUF_STATE_ERROR
 					? VB2_BUF_STATE_ERROR
 					: VB2_BUF_STATE_QUEUED;
 
+	lockdep_assert_held(&queue->irqlock);
+
 	while (!list_empty(&queue->irqqueue)) {
 		struct uvc_buffer *buf = list_first_entry(&queue->irqqueue,
 							  struct uvc_buffer,
@@ -59,6 +61,14 @@ static void uvc_queue_return_buffers(struct uvc_video_queue *queue,
 	}
 }
 
+static void uvc_queue_return_buffers(struct uvc_video_queue *queue,
+				     enum uvc_buffer_state state)
+{
+	spin_lock_irq(&queue->irqlock);
+	__uvc_queue_return_buffers(queue, state);
+	spin_unlock_irq(&queue->irqlock);
+}
+
 /* -----------------------------------------------------------------------------
  * videobuf2 queue operations
  */
@@ -171,9 +181,7 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 	if (ret == 0)
 		return 0;
 
-	spin_lock_irq(&queue->irqlock);
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
-	spin_unlock_irq(&queue->irqlock);
 
 	return ret;
 }
@@ -187,9 +195,7 @@ static void uvc_stop_streaming(struct vb2_queue *vq)
 	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
 		uvc_video_stop_streaming(uvc_queue_to_stream(queue));
 
-	spin_lock_irq(&queue->irqlock);
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
-	spin_unlock_irq(&queue->irqlock);
 }
 
 static const struct vb2_ops uvc_queue_qops = {
@@ -263,7 +269,7 @@ void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect)
 	unsigned long flags;
 
 	spin_lock_irqsave(&queue->irqlock, flags);
-	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
+	__uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
 	/*
 	 * This must be protected by the irqlock spinlock to avoid race
 	 * conditions between uvc_buffer_queue and the disconnection event that