media: videobuf2-core: drop obsolete sanity check in __vb2_queue_free()

The sanity check in __vb2_queue_free() is obsolete ever since commit
f035eb4e ("[media] videobuf2: fix lockdep warning"). Remove it and
let __vb2_queue_free() return void.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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

@@ -502,27 +502,11 @@ static void __vb2_free_mem(struct vb2_queue *q, unsigned int buffers)
  * related information, if no buffers are left return the queue to an
  * uninitialized state. Might be called even if the queue has already been freed.
  */
-static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
+static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 {
 	unsigned int buffer;
 
-	/*
-	 * Sanity check: when preparing a buffer the queue lock is released for
-	 * a short while (see __buf_prepare for the details), which would allow
-	 * a race with a reqbufs which can call this function. Removing the
-	 * buffers from underneath __buf_prepare is obviously a bad idea, so we
-	 * check if any of the buffers is in the state PREPARING, and if so we
-	 * just return -EAGAIN.
-	 */
-	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
-	     ++buffer) {
-		if (q->bufs[buffer] == NULL)
-			continue;
-		if (q->bufs[buffer]->state == VB2_BUF_STATE_PREPARING) {
-			dprintk(q, 1, "preparing buffers, cannot free\n");
-			return -EAGAIN;
-		}
-	}
+	lockdep_assert_held(&q->mmap_lock);
 
 	/* Call driver-provided cleanup function for each buffer, if provided */
 	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
@@ -616,7 +600,6 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 		q->memory = VB2_MEMORY_UNKNOWN;
 		INIT_LIST_HEAD(&q->queued_list);
 	}
-	return 0;
 }
 
 bool vb2_buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb)
@@ -798,10 +781,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 		 * queued without ever calling STREAMON.
 		 */
 		__vb2_queue_cancel(q);
-		ret = __vb2_queue_free(q, q->num_buffers);
+		__vb2_queue_free(q, q->num_buffers);
 		mutex_unlock(&q->mmap_lock);
-		if (ret)
-			return ret;
 
 		/*
 		 * In case of REQBUFS(0) return immediately without calling