/* Copyright (C) 2003 Free Software Foundation, Inc.   This file is part of the GNU C Library.   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.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, write to the Free   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA   02111-1307 USA.  */#include "pthreadP.h"#include <lowlevellock.h>unsigned long int __fork_generation attribute_hidden;static voidclear_once_control (void *arg){  pthread_once_t *once_control = (pthread_once_t *) arg;  *once_control = 0;  lll_futex_wake (once_control, INT_MAX);}int__pthread_once (once_control, init_routine)     pthread_once_t *once_control;     void (*init_routine) (void);{  while (1)    {      int oldval;      int newval;      /* Pseudo code:	   oldval = *once_control;	   if ((oldval & 2) == 0)	    {	      newval = (oldval & 3) | __fork_generation | 1;	      *once_control = newval;	    }	 Do this atomically.  */      __asm __volatile ("   l	 %1,%0\n"			"0: lhi	 %2,2\n"			"   tml	 %1,2\n"			"   jnz	 1f\n"			"   nr	 %2,%1\n"			"   ahi	 %2,1\n"			"   o	 %2,%3\n"			"   cs	 %1,%2,%0\n"			"   jl	 0b\n"			"1:"			: "=Q" (*once_control), "=&d" (oldval), "=&d" (newval)			: "m" (__fork_generation), "m" (*once_control)			: "cc" );      /* Check if the initialized has already been done.  */      if ((oldval & 2) != 0)	  break;      /* 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);	      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.  */      __asm __volatile ("   l	 %1,%0\n"			"0: lr	 %2,%1\n"			"   ahi	 %2,1\n"			"   cs	 %1,%2,%0\n"			"   jl	 0b\n"			: "=Q" (*once_control), "=&d" (oldval), "=&d" (newval)			: "m" (*once_control) : "cc" );      /* Wake up all other threads.  */      lll_futex_wake (once_control, INT_MAX);      break;    }  return 0;}weak_alias (__pthread_once, pthread_once)strong_alias (__pthread_once, __pthread_once_internal)