github.com/afumu/libc@v0.0.6/musl/src/thread/pthread_rwlock_unlock.c (about)

     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);