Am 13.06.20 um 14:30 schrieb Xiyu Yang:
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@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Reviewed and pushed this one as well as the other ttm fix to drm-misc-fixes.
That should show up in Linus tree rather soon.
Thanks for the help,
Christian.
PS: Are you working on some new automated scripts to catch that stuff or
how did you stumbled over it?
---
drivers/gpu/drm/ttm/ttm_bo.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
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);
