drm: Don't reference objects in the flink name idr

There's no reason to keep a reference to objects in the name idr.  Each
handle to an object has a reference to the object and just before we
destroy the last handle we take the object out of the name idr.  Thus,
if an object is in the name idr, there's at least one reference to the
object.

Or to put it another way, the name idr reference will never keep the
object alive.  It just looks like it, which is confusing.

Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_gem.c

@@ -175,11 +175,6 @@ drm_gem_remove_prime_handles(struct drm_gem_object *obj, struct drm_file *filp)
 	mutex_unlock(&filp->prime.lock);
 }
 
-static void drm_gem_object_ref_bug(struct kref *list_kref)
-{
-	BUG();
-}
-
 /**
  * Called after the last handle to the object has been closed
  *
@@ -195,13 +190,6 @@ static void drm_gem_object_handle_free(struct drm_gem_object *obj)
 	if (obj->name) {
 		idr_remove(&dev->object_name_idr, obj->name);
 		obj->name = 0;
-		/*
-		 * The object name held a reference to this object, drop
-		 * that now.
-		*
-		* This cannot be the last reference, since the handle holds one too.
-		 */
-		kref_put(&obj->refcount, drm_gem_object_ref_bug);
 	}
 }
 
@@ -602,9 +590,6 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 			goto err;
 
 		obj->name = ret;
-
-		/* Allocate a reference for the name table.  */
-		drm_gem_object_reference(obj);
 	}
 
 	args->name = (uint64_t) obj->name;