[PATCH] drm/amdgpu: Fix the dead lock issue.

[Emily Deng]

It will ramdomly have the dead lock issue when test TDR:
1. amdgpu_device_handle_vram_lost gets the lock shadow_list_lock
2. amdgpu_bo_create locked the bo's resv lock
3. amdgpu_bo_create_shadow is waiting for the shadow_list_lock
4. amdgpu_device_recover_vram_from_shadow is waiting for the bo's resv
lock.

Signed-off-by: Emily Deng <Emily.Deng at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index de990bd..c75447d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -557,12 +557,8 @@ static int amdgpu_bo_create_shadow(struct amdgpu_device *adev,
 	bp.resv = bo->tbo.resv;
 
 	r = amdgpu_bo_do_create(adev, &bp, &bo->shadow);
-	if (!r) {
+	if (!r)
 		bo->shadow->parent = amdgpu_bo_ref(bo);
-		mutex_lock(&adev->shadow_list_lock);
-		list_add_tail(&bo->shadow_list, &adev->shadow_list);
-		mutex_unlock(&adev->shadow_list_lock);
-	}
 
 	return r;
 }
@@ -603,6 +599,12 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
 		if (!bp->resv)
 			reservation_object_unlock((*bo_ptr)->tbo.resv);
 
+		if (!r) {
+			mutex_lock(&adev->shadow_list_lock);
+			list_add_tail(&(*bo_ptr)->shadow_list, &adev->shadow_list);
+			mutex_unlock(&adev->shadow_list_lock);
+		}
+
 		if (r)
 			amdgpu_bo_unref(bo_ptr);
 	}
-- 
2.7.4