Function mutex_unlock

examples/stdlib.c:1587–1601

}

static __attribute__((__noinline__)) int mutex_unlock(mutex_t *m)
{
    if (mutex_disabled)
        return 0;
    pid_t *x = mutex_get_ptr(m);
    pid_t self = mutex_gettid();
    while (!mutex_fast_unlock(self, x))
    {
        if (syscall(SYS_futex, x, FUTEX_UNLOCK_PI, 0, NULL, NULL, 0) != 0)
            return -1;
        if ((pid_t)(*x & ~FUTEX_WAITERS) != self)
            break;
    }
    return 0;                       // released
}

static pid_t gettid(void)
{