sysdeps/htl/pt-once.c

   1 /* pthread_once.  Generic version.
   2    Copyright (C) 2002-2018 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 <atomic.h>
  21
  22 #include <pt-internal.h>
  23
  24 int
  25 __pthread_once (pthread_once_t *once_control, void (*init_routine) (void))
  26 {
  27   atomic_full_barrier ();
  28   if (once_control->__run == 0)
  29     {
  30       __pthread_spin_lock (&once_control->__lock);
  31
  32       if (once_control->__run == 0)
  33         {
  34           init_routine ();
  35           atomic_full_barrier ();
  36           once_control->__run = 1;
  37         }
  38
  39       __pthread_spin_unlock (&once_control->__lock);
  40     }
  41
  42   return 0;
  43 }
  44 strong_alias (__pthread_once, pthread_once);