pthread_spin_lock.c

glibc 2.9,最新版的C语言库函数

/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Jakub Jelinek <[e-mail]>, 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"

int
pthread_spin_lock (lock)
     pthread_spinlock_t *lock;
{
  int *p = (int *) lock;

  while (__builtin_expect (__sync_val_compare_and_swap (p, 0, 1), 0))
    {
      /* Spin without using the atomic instruction.  */
      do
	__asm __volatile ("hint @pause" : : : "memory");
      while (*p);
    }
  return 0;
}