source: azure_iot_hub/trunk/musl-1.1.18/src/thread/pthread_rwlock_unlock.c@ 388

#include "pthread_impl.h"

int pthread_rwlock_unlock(pthread_rwlock_t *rw)
{
        int val, cnt, waiters, new, priv = rw->_rw_shared^128;

        do {
                val = rw->_rw_lock;
                cnt = val & 0x7fffffff;
                waiters = rw->_rw_waiters;
                new = (cnt == 0x7fffffff || cnt == 1) ? 0 : val-1;
        } while (a_cas(&rw->_rw_lock, val, new) != val);

        if (!new && (waiters || val<0))
                __wake(&rw->_rw_lock, cnt, priv);

        return 0;
}