[PATCH] drm/ttm: check null pointer before accessing when swapping

[Guchun Chen]

Add a check to avoid null pointer dereference.

Fixes: a2848d08742c ("drm/ttm: never consider pinned BOs for eviction&swap")
Signed-off-by: Guchun Chen <guchun.c...@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 7139a522b2f3..54e3083076b7 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -519,7 +519,8 @@ static bool ttm_bo_evict_swapout_allowable(struct 
ttm_buffer_object *bo,
 
        if (bo->pin_count) {
                *locked = false;
-               *busy = false;
+               if (busy)
+                       *busy = false;
                return false;
        }
 
-- 
2.25.1