sysdeps/htl/pt-barrier-wait.c

   1 /* pthread_barrier_wait.  Generic version.
   2    Copyright (C) 2002-2019 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library;  if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <pthread.h>
  20 #include <assert.h>
  21
  22 #include <pt-internal.h>
  23
  24 int
  25 pthread_barrier_wait (pthread_barrier_t *barrier)
  26 {
  27   __pthread_spin_lock (&barrier->__lock);
  28   if (--barrier->__pending == 0)
  29     {
  30       barrier->__pending = barrier->__count;
  31
  32       if (barrier->__count > 1)
  33         {
  34           struct __pthread *wakeup;
  35           unsigned n = 0;
  36
  37           __pthread_queue_iterate (barrier->__queue, wakeup)
  38             n++;
  39
  40           {
  41             struct __pthread *wakeups[n];
  42             unsigned i = 0;
  43
  44             __pthread_dequeuing_iterate (barrier->__queue, wakeup)
  45               wakeups[i++] = wakeup;
  46
  47             barrier->__queue = NULL;
  48             __pthread_spin_unlock (&barrier->__lock);
  49
  50             for (i = 0; i < n; i++)
  51               __pthread_wakeup (wakeups[i]);
  52           }
  53         }
  54
  55       return PTHREAD_BARRIER_SERIAL_THREAD;
  56     }
  57   else
  58     {
  59       struct __pthread *self = _pthread_self ();
  60
  61       /* Add ourselves to the list of waiters.  */
  62       __pthread_enqueue (&barrier->__queue, self);
  63       __pthread_spin_unlock (&barrier->__lock);
  64
  65       __pthread_block (self);
  66       return 0;
  67     }
  68 }