diff mbox series

drm/ttm: Fix dma_fence refcnt leak when adding move fence

Message ID 1592051425-94019-1-git-send-email-xiyuyang19@fudan.edu.cn
State New
Headers show
Series drm/ttm: Fix dma_fence refcnt leak when adding move fence | expand

Commit Message

Xiyu Yang June 13, 2020, 12:30 p.m. UTC 
ttm_bo_add_move_fence() invokes dma_fence_get(), which returns a
reference of the specified dma_fence object to "fence" with increased
refcnt.

When ttm_bo_add_move_fence() returns, local variable "fence" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
ttm_bo_add_move_fence(). When no_wait_gpu flag is equals to true, the
function forgets to decrease the refcnt increased by dma_fence_get(),
causing a refcnt leak.

Fix this issue by calling dma_fence_put() when no_wait_gpu flag is
equals to true.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index f73b81c2576e..0f20e14a4cfd 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -883,8 +883,10 @@  static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo,
 	if (!fence)
 		return 0;
 
-	if (no_wait_gpu)
+	if (no_wait_gpu) {
+		dma_fence_put(fence);
 		return -EBUSY;
+	}
 
 	dma_resv_add_shared_fence(bo->base.resv, fence);