nbcon_state_try_cmpxchg
} while (!nbcon_state_try_cmpxchg(con, cur, &new));
if (!nbcon_state_try_cmpxchg(con, cur, &new)) {
if (!nbcon_state_try_cmpxchg(con, cur, &new))
if (nbcon_state_try_cmpxchg(con, cur, &new)) {
} while (!nbcon_state_try_cmpxchg(con, cur, &new));
} while (!nbcon_state_try_cmpxchg(con, &cur, &new));
} while (!nbcon_state_try_cmpxchg(con, &cur, &new));