drm/amdgpu: destroy mutex when tearing down ttm buffer entity

Pair mutex_init() with mutex_destroy() on the GART window allocation
failure path and in amdgpu_ttm_buffer_entity_fini(). This is a no-op
without CONFIG_DEBUG_MUTEXES, but it keeps lockdep from seeing a live
mutex after the entity is freed or re-initialized.

Signed-off-by: Perry Yuan <[email protected]>
Reviewed-by: Christian König <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit 03ac40aeed034a0a0d5824ad26f8fbe1f6463698)
Cc: [email protected]

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

@@ -2081,6 +2081,7 @@ static int amdgpu_ttm_buffer_entity_init(struct amdgpu_gtt_mgr *mgr,
 	r = amdgpu_gtt_mgr_alloc_entries(mgr, &entity->gart_node, num_pages,
 					 DRM_MM_INSERT_BEST);
 	if (r) {
+		mutex_destroy(&entity->lock);
 		drm_sched_entity_destroy(&entity->base);
 		return r;
 	}
@@ -2098,6 +2099,7 @@ static void amdgpu_ttm_buffer_entity_fini(struct amdgpu_gtt_mgr *mgr,
 					  struct amdgpu_ttm_buffer_entity *entity)
 {
 	amdgpu_gtt_mgr_free_entries(mgr, &entity->gart_node);
+	mutex_destroy(&entity->lock);
 	drm_sched_entity_destroy(&entity->base);
 }