sysdeps/ia64/nptl/pthread_spin_lock.c

   1 /* Copyright (C) 2003-2019 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
   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 "pthreadP.h"
  20
  21 int
  22 pthread_spin_lock (pthread_spinlock_t *lock)
  23 {
  24   int *p = (int *) lock;
  25
  26   while (__builtin_expect (__sync_val_compare_and_swap (p, 0, 1), 0))
  27     {
  28       /* Spin without using the atomic instruction.  */
  29       do
  30         __asm __volatile ("hint @pause" : : : "memory");
  31       while (*p);
  32     }
  33   return 0;
  34 }