src/thread/pthread_mutex_timedlock.c

   1 #include "pthread_impl.h"
   2
   3 int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *restrict at)
   4 {
   5         if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL
   6             && !a_cas(&m->_m_lock, 0, EBUSY))
   7                 return 0;
   8
   9         int type = m->_m_type;
  10         int r, t, priv = (type & 128) ^ 128;
  11
  12         r = __pthread_mutex_trylock(m);
  13         if (r != EBUSY) return r;
  14
  15         int spins = 100;
  16         while (spins-- && m->_m_lock && !m->_m_waiters) a_spin();
  17
  18         while ((r=__pthread_mutex_trylock(m)) == EBUSY) {
  19                 r = m->_m_lock;
  20                 int own = r & 0x3fffffff;
  21                 if (!own && (!r || (type&4)))
  22                         continue;
  23                 if ((type&3) == PTHREAD_MUTEX_ERRORCHECK
  24                     && own == __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);