drm/ttm: call ttm_bo_wait while inside a reservation

This is the last remaining function that doesn't use the reservation
lock completely to fence off access to a buffer.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>

drivers/gpu/drm/ttm/ttm_bo.c

@@ -503,17 +503,6 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo,
 		if (ret)
 			return ret;
 
-		/*
-		 * remove sync_obj with ttm_bo_wait, the wait should be
-		 * finished, and no new wait object should have been added.
-		 */
-		spin_lock(&bdev->fence_lock);
-		ret = ttm_bo_wait(bo, false, false, true);
-		WARN_ON(ret);
-		spin_unlock(&bdev->fence_lock);
-		if (ret)
-			return ret;
-
 		spin_lock(&glob->lru_lock);
 		ret = __ttm_bo_reserve(bo, false, true, false, NULL);
 
@@ -529,7 +518,15 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo,
 			spin_unlock(&glob->lru_lock);
 			return 0;
 		}
-	} else
+
+		/*
+		 * remove sync_obj with ttm_bo_wait, the wait should be
+		 * finished, and no new wait object should have been added.
+		 */
+		spin_lock(&bdev->fence_lock);
+		ret = ttm_bo_wait(bo, false, false, true);
+		WARN_ON(ret);
+	}
 	spin_unlock(&bdev->fence_lock);
 
 	if (ret || unlikely(list_empty(&bo->ddestroy))) {
@@ -1524,6 +1521,8 @@ int ttm_bo_wait(struct ttm_buffer_object *bo,
 	void *sync_obj;
 	int ret = 0;
 
+	lockdep_assert_held(&bo->resv->lock.base);
+
 	if (likely(bo->sync_obj == NULL))
 		return 0;