- for (;;) {
- w = c->_c_waiters;
- a_fetch_add(&m->_m_waiters, w);
- if (a_cas(&c->_c_waiters, w, 0) == w) break;
- a_fetch_add(&m->_m_waiters, -w);
- }
+ a_fetch_add(&m->_m_waiters, c->_c_waiters2);
+ c->_c_waiters2 = 0;
+
+ /* Perform the futex requeue, waking one waiter unless we know
+ * that the calling thread holds the mutex. */
+ __syscall(SYS_futex, &c->_c_seq, FUTEX_REQUEUE,
+ !m->_m_type || (m->_m_lock&INT_MAX)!=pthread_self()->tid,
+ INT_MAX, &m->_m_lock);