revert previous change in cond var waiter move

[musl] / src / thread / pthread_cond_broadcast.c

diff --git a/src/thread/pthread_cond_broadcast.c b/src/thread/pthread_cond_broadcast.c
index 6002c53..7e5ea91 100644 (file)
--- a/src/thread/pthread_cond_broadcast.c
+++ b/src/thread/pthread_cond_broadcast.c
@@ -1,9 +1,48 @@
 #include "pthread_impl.h"
 
+static void unlock(pthread_cond_t *c)
+{
+       a_dec(&c->_c_bcast);
+       if (c->_c_leavers) __wake(&c->_c_bcast, -1, 0);
+}
+
 int pthread_cond_broadcast(pthread_cond_t *c)
 {
-       int w = c->_c_waiters;
-       if (a_swap(&c->_c_block, 0) || w)
+       pthread_mutex_t *m;
+       int w;
+
+       if (!c->_c_waiters) return 0;
+       a_inc(&c->_c_bcast);
+       if (!c->_c_waiters) {
+               unlock(c);
+               return 0;
+       }
+
+       a_store(&c->_c_block, 0);
+
+       m = c->_c_mutex;
+
+       /* If mutex ptr is not available, simply wake all waiters. */
+       if (m == (void *)-1) {
+               unlock(c);
                __wake(&c->_c_block, -1, 0);
+               return 0;
+       }
+
+       /* Move waiter count to the mutex */
+       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);
+       }
+
+       /* Perform the futex requeue, waking one waiter unless we know
+        * that the calling thread holds the mutex. */
+       __syscall(SYS_futex, &c->_c_block, FUTEX_REQUEUE,
+               !m->_m_type || (m->_m_lock&INT_MAX)!=pthread_self()->tid,
+               INT_MAX, &m->_m_lock);
+
+       unlock(c);
        return 0;
 }