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| | #include "pthread_impl.h"
#include <threads.h>
int cnd_broadcast(cnd_t *c)
{
mtx_t *m;
if (!c->_c_waiters) return thrd_success;
a_inc(&c->_c_seq);
/* Block waiters from returning so we can use the mutex. */
while (a_swap(&c->_c_lock, 1))
__wait(&c->_c_lock, &c->_c_lockwait, 1, 1);
if (!c->_c_waiters)
goto out;
m = c->_c_mutex;
/* Move waiter count to the mutex */
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);
out:
a_store(&c->_c_lock, 0);
if (c->_c_lockwait) __wake(&c->_c_lock, 1, 0);
return thrd_success;
}
|