1/* Copyright (C) 2005-2017 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@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_MUTEX_H
31#define GOMP_MUTEX_H 1
32
33typedef int gomp_mutex_t;
34
35#define GOMP_MUTEX_INIT_0 1
36
37extern void gomp_mutex_lock_slow (gomp_mutex_t *mutex, int);
38extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex);
39
40static inline void
41gomp_mutex_init (gomp_mutex_t *mutex)
42{
43 *mutex = 0;
44}
45
46static inline void
47gomp_mutex_destroy (gomp_mutex_t *mutex)
48{
49}
50
51static inline void
52gomp_mutex_lock (gomp_mutex_t *mutex)
53{
54 int oldval = 0;
55 if (!__atomic_compare_exchange_n (mutex, &oldval, 1, false,
56 MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
57 gomp_mutex_lock_slow (mutex, oldval);
58}
59
60static inline void
61gomp_mutex_unlock (gomp_mutex_t *mutex)
62{
63 int wait = __atomic_exchange_n (mutex, 0, MEMMODEL_RELEASE);
64 if (__builtin_expect (wait < 0, 0))
65 gomp_mutex_unlock_slow (mutex);
66}
67#endif /* GOMP_MUTEX_H */
68