aa_sunaddr
struct sockaddr_un *addr = aa_sunaddr(u, &addrlen);
struct sockaddr_un *paddr = aa_sunaddr(unix_sk(peer_sk), &plen);
addr = aa_sunaddr(unix_sk(sock->sk), &addrlen);
peer_addr = aa_sunaddr(unix_sk(peer_sk), &peer_addrlen);
struct sockaddr_un *aa_sunaddr(const struct unix_sock *u, int *addrlen);
struct sockaddr_un *addr = aa_sunaddr(u, &addrlen);