turnstile_exit
turnstile_exit(mtx);
turnstile_exit(mtx);
turnstile_exit(mtx);
turnstile_exit(mtx);
turnstile_exit(mtx);
turnstile_exit(rw);
turnstile_exit(rw);
turnstile_exit(rw);
turnstile_exit(rw);
void turnstile_exit(wchan_t);