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 -a_xchg(&m->_m_lock, 1) & EBUSY;
   9
  10         tid = pthread_self()->tid;
  11
  12         if (m->_m_owner == tid) {
  13                 if (m->_m_type != PTHREAD_MUTEX_RECURSIVE)
  14                         return EDEADLK;
  15                 if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
  16                 m->_m_count++;
  17                 return 0;
  18         }
  19
  20         if (a_xchg(&m->_m_lock, 1)) return EBUSY;
  21         m->_m_owner = tid;
  22         m->_m_count = 1;
  23         return 0;
  24 }