drm/amdgpu:fix waiting on dirty fence

if bo->shadow is NULL (race issue:BO shadow was just released
and gpu-reset kick in but BO hasn't yet) recover_vram_from_shadow
won't set @next, so the following "fence=next"
will wrongly use a fence pointer which may already dirty.
fixing it by set next to NULL prior to recover_vram_from_shadow

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Chunming Zhou<david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 3c1754df4c40..367811cd0763 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -2522,6 +2522,7 @@ int amdgpu_sriov_gpu_reset(struct amdgpu_device *adev, bool voluntary)
         ring = adev->mman.buffer_funcs_ring;
         mutex_lock(&adev->shadow_list_lock);
         list_for_each_entry_safe(bo, tmp, &adev->shadow_list, shadow_list) {
+                next = NULL;
                 amdgpu_recover_vram_from_shadow(adev, ring, bo, &next);
                 if (fence) {
                         r = dma_fence_wait(fence, false);
@@ -2668,6 +2669,7 @@ retry:
                         DRM_INFO("recover vram bo from shadow\n");
                         mutex_lock(&adev->shadow_list_lock);
                         list_for_each_entry_safe(bo, tmp, &adev->shadow_list, shadow_list) {
+                                next = NULL;
                                 amdgpu_recover_vram_from_shadow(adev, ring, bo, &next);
                                 if (fence) {
                                         r = dma_fence_wait(fence, false);