nsz Git - musl/blob - src/thread/pthread_mutex_trylock.c

   1 #include "pthread_impl.h"
   2
   3 int pthread_mutex_trylock(pthread_mutex_t *m)
   4 {
   5         int tid;
   6
   7         if (m->_m_type == PTHREAD_MUTEX_NORMAL)
   8                 return (m->_m_lock || a_swap(&m->_m_lock, 1)) ? EBUSY : 0;
   9
  10         tid = pthread_self()->tid;
  11
  12         if (m->_m_lock == tid && m->_m_type == PTHREAD_MUTEX_RECURSIVE) {
  13                 if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
  14                 m->_m_count++;
  15                 return 0;
  16         }
  17
  18         if (m->_m_lock || a_cas(&m->_m_lock, 0, tid)) return EBUSY;
  19         m->_m_count = 1;
  20         return 0;
  21 }