drm/msm: Drop struct_mutex in free_object() path

Now that active_list/inactive_list is protected by mm_lock, we no longer
need dev->struct_mutex in the free_object() path.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_gem.c

@@ -948,8 +948,6 @@ static void free_object(struct msm_gem_object *msm_obj)
 	struct drm_device *dev = obj->dev;
 	struct msm_drm_private *priv = dev->dev_private;
 
-	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
-
 	/* object should not be on active list: */
 	WARN_ON(is_active(msm_obj));
 
@@ -991,20 +989,14 @@ void msm_gem_free_work(struct work_struct *work)
 {
 	struct msm_drm_private *priv =
 		container_of(work, struct msm_drm_private, free_work);
-	struct drm_device *dev = priv->dev;
 	struct llist_node *freed;
 	struct msm_gem_object *msm_obj, *next;
 
 	while ((freed = llist_del_all(&priv->free_list))) {
-
-		mutex_lock(&dev->struct_mutex);
-
 		llist_for_each_entry_safe(msm_obj, next,
 					  freed, freed)
 			free_object(msm_obj);
 
-		mutex_unlock(&dev->struct_mutex);
-
 		if (need_resched())
 			break;
 	}