[v4 5/5] drm/amdgpu: fix invalid memory access in amdgpu_fence_driver_sw_fini()

[Jiang Liu]

Function detects initialization status by checking sched->ops, so set
sched->ops to non-NULL just before return in function
amdgpu_fence_driver_sw_fini() and amdgpu_device_init_schedulers()
to avoid possible invalid memory access on error recover path.

Signed-off-by: Jiang Liu <ge...@linux.alibaba.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c  | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index f29a4ad3c6d0..3688e9eb949b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -2857,6 +2857,7 @@ static int amdgpu_device_init_schedulers(struct 
amdgpu_device *adev)
                if (r) {
                        DRM_ERROR("Failed to create scheduler on ring %s.\n",
                                  ring->name);
+                       ring->sched.ops = NULL;
                        return r;
                }
                r = amdgpu_uvd_entity_init(adev, ring);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index 2f24a6aa13bf..b5e87b515139 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -656,8 +656,10 @@ void amdgpu_fence_driver_sw_fini(struct amdgpu_device 
*adev)
                 * The natural check would be sched.ready, which is
                 * set as drm_sched_init() finishes...
                 */
-               if (ring->sched.ops)
+               if (ring->sched.ops) {
                        drm_sched_fini(&ring->sched);
+                       ring->sched.ops = NULL;
+               }
 
                for (j = 0; j <= ring->fence_drv.num_fences_mask; ++j)
                        dma_fence_put(ring->fence_drv.fences[j]);
-- 
2.43.5