static void __exit xfrm6_tunnel_fini(void)
{
	xfrm6_tunnel_deregister(&xfrm46_tunnel_handler, AF_INET);
	xfrm6_tunnel_deregister(&xfrm6_tunnel_handler, AF_INET6);
	xfrm_unregister_type(&xfrm6_tunnel_type, AF_INET6);
	unregister_pernet_subsys(&xfrm6_tunnel_net_ops);
	kmem_cache_destroy(xfrm6_tunnel_spi_kmem);
}
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.