nptl/pthread_spin_unlock.c

   1 /* pthread_spin_unlock -- unlock a spin lock.  Generic version.
   2    Copyright (C) 2003-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include "pthreadP.h"
  21 #include <atomic.h>
  22
  23 int
  24 pthread_spin_unlock (pthread_spinlock_t *lock)
  25 {
  26   /* The atomic_store_release synchronizes-with the atomic_exchange_acquire
  27      or atomic_compare_exchange_weak_acquire in pthread_spin_lock /
  28      pthread_spin_trylock.  */
  29   atomic_store_release (lock, 0);
  30   return 0;
  31 }