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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [sys/] [linux/] [linuxthreads/] [barrier.c] - Blame information for rev 207

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1 207 jeremybenn
/* POSIX barrier implementation for LinuxThreads.
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   Copyright (C) 2000 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>, 2000.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Library General Public License as
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   published by the Free Software Foundation; either version 2 of the
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   License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Library General Public License for more details.
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   You should have received a copy of the GNU Library General Public
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   License along with the GNU C Library; see the file COPYING.LIB.  If not,
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   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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   Boston, MA 02111-1307, USA.  */
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#include <errno.h>
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#include "pthread.h"
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#include "internals.h"
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#include "spinlock.h"
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#include "queue.h"
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#include "restart.h"
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int
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pthread_barrier_wait(pthread_barrier_t *barrier)
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{
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  pthread_descr self = thread_self();
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  pthread_descr temp_wake_queue, th;
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  int result = 0;
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  __pthread_lock(&barrier->__ba_lock, self);
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  /* If the required number of threads have achieved rendezvous... */
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  if (barrier->__ba_present >= barrier->__ba_required - 1)
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    {
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      /* ... then this last caller shall be the serial thread */
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      result = PTHREAD_BARRIER_SERIAL_THREAD;
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      /* Copy and clear wait queue and reset barrier. */
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      temp_wake_queue = barrier->__ba_waiting;
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      barrier->__ba_waiting = NULL;
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      barrier->__ba_present = 0;
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    }
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  else
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    {
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      result = 0;
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      barrier->__ba_present++;
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      enqueue(&barrier->__ba_waiting, self);
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    }
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  __pthread_unlock(&barrier->__ba_lock);
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  if (result == 0)
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    {
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      /* Non-serial threads have to suspend */
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      suspend(self);
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      /* We don't bother dealing with cancellation because the POSIX
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         spec for barriers doesn't mention that pthread_barrier_wait
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         is a cancellation point. */
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    }
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  else
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    {
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      /* Serial thread wakes up all others. */
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      while ((th = dequeue(&temp_wake_queue)) != NULL)
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        restart(th);
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    }
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  return result;
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}
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int
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pthread_barrier_init(pthread_barrier_t *barrier,
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                                const pthread_barrierattr_t *attr,
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                                unsigned int count)
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{
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  if (count == 0)
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     return EINVAL;
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  __pthread_init_lock(&barrier->__ba_lock);
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  barrier->__ba_required = count;
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  barrier->__ba_present = 0;
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  barrier->__ba_waiting = NULL;
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  return 0;
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}
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int
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pthread_barrier_destroy(pthread_barrier_t *barrier)
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{
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  if (barrier->__ba_waiting != NULL) return EBUSY;
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  return 0;
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}
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int
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pthread_barrierattr_init(pthread_barrierattr_t *attr)
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{
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  attr->__pshared = PTHREAD_PROCESS_PRIVATE;
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  return 0;
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}
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int
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pthread_barrierattr_destroy(pthread_barrierattr_t *attr)
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{
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  return 0;
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}
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int
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__pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr,
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                                 int *pshared)
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{
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  *pshared = attr->__pshared;
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  return 0;
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}
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int
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pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared)
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{
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  if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
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    return EINVAL;
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  attr->__pshared = pshared;
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  return 0;
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}

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