drm/amdgpu: fix NULL fence handling in amdgpu_cs_fence_to_handle_ioctl

When the fence is already signaled it is perfectly normal to get a NULL
fence here. But since we can't export that we need to use a stub fence.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 5dc3ee372e2f..149b3065119b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -1428,6 +1428,9 @@ int amdgpu_cs_fence_to_handle_ioctl(struct drm_device *dev, void *data,
         if (IS_ERR(fence))
                 return PTR_ERR(fence);
 
+        if (!fence)
+                fence = dma_fence_get_stub();
+
         switch (info->in.what) {
         case AMDGPU_FENCE_TO_HANDLE_GET_SYNCOBJ:
                 r = drm_syncobj_create(&syncobj, 0, fence);