drm/ttm: introduce ttm_bo_move_null

This pattern is cut-n-pasted across 4 drivers, switch it to
a WARN_ON instead, as BUG_ON is considered a bad idea usually.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200907204630.1406528-2-airlied@gmail.com

1 files changed, 17 insertions, 0 deletions

diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index a694388f7b13..ebba282667ba 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -521,6 +521,23 @@ static inline void ttm_bo_move_to_lru_tail_unlocked(struct ttm_buffer_object *bo
 }
 
 /**
+ * ttm_bo_move_null = assign memory for a buffer object.
+ * @bo: The bo to assign the memory to
+ * @new_mem: The memory to be assigned.
+ *
+ * Assign the memory from new_mem to the memory of the buffer object bo.
+ */
+static inline void ttm_bo_move_null(struct ttm_buffer_object *bo,
+				    struct ttm_resource *new_mem)
+{
+	struct ttm_resource *old_mem = &bo->mem;
+
+	WARN_ON(old_mem->mm_node != NULL);
+	*old_mem = *new_mem;
+	new_mem->mm_node = NULL;
+}
+
+/**
  * ttm_bo_unreserve
  *
  * @bo: A pointer to a struct ttm_buffer_object.