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

   1 #include "pthread_impl.h"
   2
   3 int __pthread_mutex_trylock(pthread_mutex_t *);
   4
   5 int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *restrict at)
   6 {
   7         if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL
   8             && !a_cas(&m->_m_lock, 0, EBUSY))
   9                 return 0;
  10
  11         int type = m->_m_type;
  12         int r, t, priv = (type & 128) ^ 128;
  13
  14         r = pthread_mutex_trylock(m);
  15         if (r != EBUSY) return r;
  16
  17         int spins = 100;
  18         while (spins-- && m->_m_lock && !m->_m_waiters) a_spin();
  19
  20         while ((r=__pthread_mutex_trylock(m)) == EBUSY) {
  21                 if (!(r=m->_m_lock) || ((r&0x40000000) && (type&4)))
  22                         continue;
  23                 if ((type&3) == PTHREAD_MUTEX_ERRORCHECK
  24                  && (r&0x7fffffff) == __pthread_self()->tid)
  25                         return EDEADLK;
  26
  27                 a_inc(&m->_m_waiters);
  28                 t = r | 0x80000000;
  29                 a_cas(&m->_m_lock, r, t);
  30                 r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, priv);
  31                 a_dec(&m->_m_waiters);
  32                 if (r && r != EINTR) break;
  33         }
  34         return r;
  35 }
  36
  37 weak_alias(__pthread_mutex_timedlock, pthread_mutex_timedlock);