[17/19] drm/ttm: fix ttm_bo_add_ttm(user) failure path

[Greg KH <gregkh@suse.de>]

2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------

From: Marcin Slusarz <marcin.slusarz@gmail.com>

commit 7c4c3960dff109bc5db4c35da481c212dadb5eb5 upstream.

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

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/gpu/drm/ttm/ttm_bo.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -281,8 +281,10 @@ static int ttm_bo_add_ttm(struct ttm_buf
 
 		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");