sysdeps/htl/pt-barrier-wait.c

   1 /* pthread_barrier_wait.  Generic version.
   2    Copyright (C) 2002-2023 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    <https://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_wait (&barrier->__lock);
  28   if (--barrier->__pending == 0)
  29     {
  30       barrier->__pending = barrier->__count;
  31
  32       if (barrier->__count == 1)
  33         __pthread_spin_unlock (&barrier->__lock);
  34       else
  35         {
  36           struct __pthread *wakeup;
  37           unsigned n = 0;
  38
  39           __pthread_queue_iterate (barrier->__queue, wakeup)
  40             n++;
  41
  42           {
  43             struct __pthread *wakeups[n];
  44             unsigned i = 0;
  45
  46             __pthread_dequeuing_iterate (barrier->__queue, wakeup)
  47               wakeups[i++] = wakeup;
  48
  49             barrier->__queue = NULL;
  50             __pthread_spin_unlock (&barrier->__lock);
  51
  52             for (i = 0; i < n; i++)
  53               __pthread_wakeup (wakeups[i]);
  54           }
  55         }
  56
  57       return PTHREAD_BARRIER_SERIAL_THREAD;
  58     }
  59   else
  60     {
  61       struct __pthread *self = _pthread_self ();
  62
  63       /* Add ourselves to the list of waiters.  */
  64       __pthread_enqueue (&barrier->__queue, self);
  65       __pthread_spin_unlock (&barrier->__lock);
  66
  67       __pthread_block (self);
  68       return 0;
  69     }
  70 }