[media] vb2: properly clean up PREPARED and QUEUED buffers

If __reqbufs was called then existing buffers are freed. However, if that
happens without ever having started STREAMON, but if buffers have been queued,
then the buf_finish op is never called.

Add a call to __vb2_queue_cancel in __reqbufs so that these buffers are
cleaned up there as well.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/v4l2-core/videobuf2-core.c

@@ -100,6 +100,8 @@ module_param(debug, int, 0644);
 #define V4L2_BUFFER_OUT_FLAGS	(V4L2_BUF_FLAG_PFRAME | V4L2_BUF_FLAG_BFRAME | \
 				 V4L2_BUF_FLAG_KEYFRAME | V4L2_BUF_FLAG_TIMECODE)
 
+static void __vb2_queue_cancel(struct vb2_queue *q);
+
 /**
  * __vb2_buf_mem_alloc() - allocate video memory for the given buffer
  */
@@ -802,6 +804,12 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 			return -EBUSY;
 		}
 
+		/*
+		 * Call queue_cancel to clean up any buffers in the PREPARED or
+		 * QUEUED state which is possible if buffers were prepared or
+		 * queued without ever calling STREAMON.
+		 */
+		__vb2_queue_cancel(q);
 		ret = __vb2_queue_free(q, q->num_buffers);
 		if (ret)
 			return ret;