drm/amd/amdgpu: lock reservation object while creating shadow bo

ttm_bo_init checks that the reservation object is locked. This is
the caller's responsibility when resv != NULL. Otherwise, the inline
reservation object of the newly allocated buffer is used and must
explicitly be locked.

Uninterruptible w/w locks without an acquire context are always
successful.

v2: use ww_mutex_lock
Signed-off-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net> (v1)
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_object.c

@@ -472,7 +472,16 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
 		return r;
 
 	if (amdgpu_need_backup(adev) && (flags & AMDGPU_GEM_CREATE_SHADOW)) {
+		if (!resv) {
+			r = ww_mutex_lock(&(*bo_ptr)->tbo.resv->lock, NULL);
+			WARN_ON(r != 0);
+		}
+
 		r = amdgpu_bo_create_shadow(adev, size, byte_align, (*bo_ptr));
+
+		if (!resv)
+			ww_mutex_unlock(&(*bo_ptr)->tbo.resv->lock);
+
 		if (r)
 			amdgpu_bo_unref(bo_ptr);
 	}