1/* Copyright (C) 2008-2015 Free Software Foundation, Inc. 2 Contributed by Jakub Jelinek <jakub@redhat.com>. 3 4 This file is part of the GNU Offloading and Multi Processing Library 5 (libgomp). 6 7 Libgomp is free software; you can redistribute it and/or modify it 8 under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3, or (at your option) 10 any later version. 11 12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY 13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 more details. 16 17 Under Section 7 of GPL version 3, you are granted additional 18 permissions described in the GCC Runtime Library Exception, version 19 3.1, as published by the Free Software Foundation. 20 21 You should have received a copy of the GNU General Public License and 22 a copy of the GCC Runtime Library Exception along with this program; 23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 <http://www.gnu.org/licenses/>. */ 25 26/* This is a Linux specific implementation of a mutex synchronization 27 mechanism for libgomp. This type is private to the library. This 28 implementation uses atomic instructions and the futex syscall. */ 29 30#ifndef GOMP_WAIT_H 31#define GOMP_WAIT_H 1 32 33#include "libgomp.h" 34#include <errno.h> 35 36#define FUTEX_WAIT 0 37#define FUTEX_WAKE 1 38#define FUTEX_PRIVATE_FLAG 128L 39 40#ifdef HAVE_ATTRIBUTE_VISIBILITY 41# pragma GCC visibility push(hidden) 42#endif 43 44extern long int gomp_futex_wait, gomp_futex_wake; 45 46#include <futex.h> 47 48static inline int do_spin (int *addr, int val) 49{ 50 unsigned long long i, count = gomp_spin_count_var; 51 52 if (__builtin_expect (__atomic_load_n (&gomp_managed_threads, 53 MEMMODEL_RELAXED) 54 > gomp_available_cpus, 0)) 55 count = gomp_throttled_spin_count_var; 56 for (i = 0; i < count; i++) 57 if (__builtin_expect (__atomic_load_n (addr, MEMMODEL_RELAXED) != val, 0)) 58 return 0; 59 else 60 cpu_relax (); 61 return 1; 62} 63 64static inline void do_wait (int *addr, int val) 65{ 66 if (do_spin (addr, val)) 67 futex_wait (addr, val); 68} 69 70#ifdef HAVE_ATTRIBUTE_VISIBILITY 71# pragma GCC visibility pop 72#endif 73 74#endif /* GOMP_WAIT_H */ 75