[PATCH] drm/ttm: fix ttm_bo_add_ttm(user) failure path

[Marcin Slusarz]

ttm_tt_destroy kfrees passed object, so we need to nullify
a reference to it.

Signed-off-by: Marcin Slusarz <marcin.slusarz at gmail.com>
Cc: stable at kernel.org
---
 drivers/gpu/drm/ttm/ttm_bo.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 251df77..2e8f929 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -353,8 +353,10 @@ static int ttm_bo_add_ttm(struct ttm_buffer_object *bo, bool zero_alloc)
 
 		ret = ttm_tt_set_user(bo->ttm, current,
 				      bo->buffer_start, bo->num_pages);
-		if (unlikely(ret != 0))
+		if (unlikely(ret != 0)) {
 			ttm_tt_destroy(bo->ttm);
+			bo->ttm = NULL;
+		}
 		break;
 	default:
 		printk(KERN_ERR TTM_PFX "Illegal buffer object type\n");
-- 
1.7.6