[PATCH 2/3] drivers/media/media-entity: clear media_gobj.mdev in _destroy()

[Max Kellermann]

media_gobj_destroy() may be called twice on one instance - once by
media_device_unregister() and again by dvb_media_device_free().  The
function media_remove_intf_links() establishes and documents the
convention that mdev==NULL means that the object is not registered,
but nobody ever NULLs this variable.  So this patch really implements
this behavior, and adds another mdev==NULL check to
media_gobj_destroy() to protect against double removal.

Signed-off-by: Max Kellermann <max@xxxxxxxxxxx>
---
 drivers/media/media-entity.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index d8a2299..9526338 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -203,10 +203,16 @@ void media_gobj_destroy(struct media_gobj *gobj)
 {
 	dev_dbg_obj(__func__, gobj);
 
+	/* Do nothing if the object is not linked. */
+	if (gobj->mdev == NULL)
+		return;
+
 	gobj->mdev->topology_version++;
 
 	/* Remove the object from mdev list */
 	list_del(&gobj->list);
+
+	gobj->mdev = NULL;
 }
 
 int media_entity_pads_init(struct media_entity *entity, u16 num_pads,