src/thread/pthread_rwlock_unlock.c

   1 #include "pthread_impl.h"
   2
   3 int __pthread_rwlock_unlock(pthread_rwlock_t *rw)
   4 {
   5         int val, cnt, waiters, new, priv = rw->_rw_shared^128;
   6
   7         do {
   8                 val = rw->_rw_lock;
   9                 cnt = val & 0x7fffffff;
  10                 waiters = rw->_rw_waiters;
  11                 new = (cnt == 0x7fffffff || cnt == 1) ? 0 : val-1;
  12         } while (a_cas(&rw->_rw_lock, val, new) != val);
  13
  14         if (!new && (waiters || val<0))
  15                 __wake(&rw->_rw_lock, cnt, priv);
  16
  17         return 0;
  18 }
  19
  20 weak_alias(__pthread_rwlock_unlock, pthread_rwlock_unlock);