[PATCH] drm/qxl: unset a pointer in sync_obj_unref

[Maarten Lankhorst]

This fixes a BUG_ON(bo->sync_obj != NULL); in ttm_bo_release_list.

Cc: stable at vger.kernel.org #v3.10+
     
Signed-off-by: Maarten Lankhorst <maarten.lankhorst at canonical.com>
---
diff --git a/drivers/gpu/drm/qxl/qxl_ttm.c b/drivers/gpu/drm/qxl/qxl_ttm.c
index c7e7e6590c2b..c82c1d6a965a 100644
--- a/drivers/gpu/drm/qxl/qxl_ttm.c
+++ b/drivers/gpu/drm/qxl/qxl_ttm.c
@@ -433,6 +433,7 @@ static int qxl_sync_obj_flush(void *sync_obj)
  
  static void qxl_sync_obj_unref(void **sync_obj)
  {
+	*sync_obj = NULL;
  }
  
  static void *qxl_sync_obj_ref(void *sync_obj)