pthread_rwlock_unlock.c raw

   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);
  21