text: /* Copyright (C) 2003-2013 Free Software Foundation, Inc.
     Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, see
     <http://www.gnu.org/licenses/>.  */
  
  #include "pthreadP.h"
  #include <lowlevellock.h>
  
  unsigned long int __fork_generation attribute_hidden;
  
  static void
  clear_once_control (void *arg)
  {
    pthread_once_t *once_control = (pthread_once_t *) arg;
  
    *once_control = 0;
    lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
  }
  
  
  int
  __pthread_once (once_control, init_routine)
       pthread_once_t *once_control;
       void (*init_routine) (void);
  {
    while (1)
      {
        int oldval, val, newval;
  
        val = *once_control;
        do
  	{
  	  /* Check if the initialized has already been done.  */
  	  if ((val & 2) != 0)
  	    return 0;
  
  	  oldval = val;
  	  newval = (oldval & 3) | __fork_generation | 1;
  	  val = atomic_compare_and_exchange_val_acq (once_control, newval,
  						     oldval);
  	}
        while (__builtin_expect (val != oldval, 0));
  
        /* Check if another thread already runs the initializer.	*/
        if ((oldval & 1) != 0)
  	{
  	  /* Check whether the initializer execution was interrupted
  	     by a fork.	 */
  	  if (((oldval ^ newval) & -4) == 0)
  	    {
  	      /* Same generation, some other thread was faster. Wait.  */
  	      lll_futex_wait (once_control, newval, LLL_PRIVATE);
  	      continue;
  	    }
  	}
  
        /* This thread is the first here.  Do the initialization.
  	 Register a cleanup handler so that in case the thread gets
  	 interrupted the initialization can be restarted.  */
        pthread_cleanup_push (clear_once_control, once_control);
  
        init_routine ();
  
        pthread_cleanup_pop (0);
  
  
        /* Add one to *once_control.  */
        atomic_increment (once_control);
  
        /* Wake up all other threads.  */
        lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
        break;
      }
  
    return 0;
  }
  weak_alias (__pthread_once, pthread_once)
  strong_alias (__pthread_once, __pthread_once_internal)
  