[media] media: Don't accept early-created links

Links are graph objects that represent the links of two already
existing objects in the graph.

While with the current implementation, it is possible to create
the links earlier, It doesn't make any sense to allow linking
two objects when they are not both created.

So, remove the code that would be handling those early-created
links and add a BUG_ON() to ensure that.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/media-device.c

@@ -443,13 +443,6 @@ int __must_check media_device_register_entity(struct media_device *mdev,
 	media_gobj_init(mdev, MEDIA_GRAPH_ENTITY, &entity->graph_obj);
 	list_add_tail(&entity->list, &mdev->entities);
 
-	/*
-	 * Initialize objects at the links
-	 * in the case where links got created before entity register
-	 */
-	for (i = 0; i < entity->num_links; i++)
-		media_gobj_init(mdev, MEDIA_GRAPH_LINK,
-				&entity->links[i].graph_obj);
 	/* Initialize objects at the pads */
 	for (i = 0; i < entity->num_pads; i++)
 		media_gobj_init(mdev, MEDIA_GRAPH_PAD,

drivers/media/media-entity.c

@@ -149,6 +149,8 @@ void media_gobj_init(struct media_device *mdev,
 			   enum media_gobj_type type,
 			   struct media_gobj *gobj)
 {
+	BUG_ON(!mdev);
+
 	gobj->mdev = mdev;
 
 	/* Create a per-type unique object ID */