1  /* Copyright (C) 2005-2023 Free Software Foundation, Inc.
       2     Contributed by Richard Henderson <rth@redhat.com>.
       3  
       4     This file is part of the GNU Offloading and Multi Processing Library
       5     (libgomp).
       6  
       7     Libgomp is free software; you can redistribute it and/or modify it
       8     under the terms of the GNU General Public License as published by
       9     the Free Software Foundation; either version 3, or (at your option)
      10     any later version.
      11  
      12     Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
      13     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
      14     FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
      15     more details.
      16  
      17     Under Section 7 of GPL version 3, you are granted additional
      18     permissions described in the GCC Runtime Library Exception, version
      19     3.1, as published by the Free Software Foundation.
      20  
      21     You should have received a copy of the GNU General Public License and
      22     a copy of the GCC Runtime Library Exception along with this program;
      23     see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      24     <http://www.gnu.org/licenses/>.  */
      25  
      26  /* This is the default POSIX 1003.1b implementation of a semaphore
      27     synchronization mechanism for libgomp.  This type is private to
      28     the library.
      29  
      30     This is a bit heavy weight for what we need, in that we're not
      31     interested in sem_wait as a cancelation point, but it's not too
      32     bad for a default.  */
      33  
      34  #include "libgomp.h"
      35  
      36  #ifdef HAVE_BROKEN_POSIX_SEMAPHORES
      37  #include <stdlib.h>
      38  
      39  void gomp_sem_init (gomp_sem_t *sem, int value)
      40  {
      41    int ret;
      42  
      43    ret = pthread_mutex_init (&sem->mutex, NULL);
      44    if (ret)
      45      return;
      46  
      47    ret = pthread_cond_init (&sem->cond, NULL);
      48    if (ret)
      49      return;
      50  
      51    sem->value = value;
      52  }
      53  
      54  void gomp_sem_wait (gomp_sem_t *sem)
      55  {
      56    int ret;
      57  
      58    ret = pthread_mutex_lock (&sem->mutex);
      59    if (ret)
      60      return;
      61  
      62    if (sem->value > 0)
      63      {
      64        sem->value--;
      65        ret = pthread_mutex_unlock (&sem->mutex);
      66        return;
      67      }
      68  
      69    while (sem->value <= 0)
      70      {
      71        ret = pthread_cond_wait (&sem->cond, &sem->mutex);
      72        if (ret)
      73  	{
      74  	  pthread_mutex_unlock (&sem->mutex);
      75  	  return;
      76  	}
      77      }
      78  
      79    sem->value--;
      80    ret = pthread_mutex_unlock (&sem->mutex);
      81    return;
      82  }
      83  
      84  void gomp_sem_post (gomp_sem_t *sem)
      85  {
      86    int ret;
      87  
      88    ret = pthread_mutex_lock (&sem->mutex);
      89    if (ret)
      90      return;
      91  
      92    sem->value++;
      93  
      94    ret = pthread_mutex_unlock (&sem->mutex);
      95    if (ret)
      96      return;
      97  
      98    ret = pthread_cond_signal (&sem->cond);
      99  
     100    return;
     101  }
     102  
     103  void gomp_sem_destroy (gomp_sem_t *sem)
     104  {
     105    int ret;
     106  
     107    ret = pthread_mutex_destroy (&sem->mutex);
     108    if (ret)
     109      return;
     110  
     111    ret = pthread_cond_destroy (&sem->cond);
     112  
     113    return;
     114  }
     115  
     116  int gomp_sem_getcount (gomp_sem_t *sem)
     117  {
     118    int ret, count;
     119  
     120    ret = pthread_mutex_lock (&sem->mutex);
     121    if (ret)
     122      return -1;
     123  
     124    count = sem->value;
     125  
     126    ret = pthread_mutex_unlock (&sem->mutex);
     127    if (ret)
     128      return -1;
     129  
     130    if (count < 0)
     131      return -1;
     132  
     133    return count;
     134  }
     135  #else /* HAVE_BROKEN_POSIX_SEMAPHORES  */
     136  void
     137  gomp_sem_wait (gomp_sem_t *sem)
     138  {
     139    /* With POSIX, the wait can be canceled by signals.  We don't want that.
     140       It is expected that the return value here is -1 and errno is EINTR.  */
     141    while (sem_wait (sem) != 0)
     142      continue;
     143  }
     144  #endif