common_lock.h revision 1.2 
1/* $NetBSD: common_lock.h,v 1.2 2017/09/16 23:30:50 christos Exp $ */
2
3/*-
4 * Copyright (c) 2014 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Matt Thomas of 3am Software Foundry.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*
33 * Machine-dependent spin lock operations using the builtin compiler atomic
34 * primitives.
35 */
36
37#ifndef _SYS_COMMON_LOCK_H_
38#define	_SYS_COMMON_LOCK_H_
39
40static __inline int
41__SIMPLELOCK_LOCKED_P(const __cpu_simple_lock_t *__ptr)
42{
43	return *__ptr != __SIMPLELOCK_UNLOCKED;
44}
45
46static __inline int
47__SIMPLELOCK_UNLOCKED_P(const __cpu_simple_lock_t *__ptr)
48{
49	return *__ptr == __SIMPLELOCK_UNLOCKED;
50}
51
52static __inline void
53__cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr)
54{
55#if 1
56	*__ptr = __SIMPLELOCK_UNLOCKED;
57#else
58	__atomic_store_n(__ptr, __SIMPLELOCK_UNLOCKED, __ATOMIC_RELAXED);
59#endif
60}
61
62static __inline void
63__cpu_simple_lock_set(__cpu_simple_lock_t *__ptr)
64{
65#if 1
66	*__ptr = __SIMPLELOCK_LOCKED;
67#else
68	__atomic_store_n(__ptr, __SIMPLELOCK_LOCKED, __ATOMIC_RELAXED);
69#endif
70}
71
72static __inline void __unused
73__cpu_simple_lock_init(__cpu_simple_lock_t *__ptr)
74{
75#if 1
76	*__ptr = __SIMPLELOCK_UNLOCKED;
77#else
78	__atomic_store_n(__ptr, __SIMPLELOCK_UNLOCKED, __ATOMIC_RELAXED);
79#endif
80}
81
82static __inline void __unused
83__cpu_simple_lock(__cpu_simple_lock_t *__ptr)
84{
85	while (__atomic_exchange_n(__ptr, __SIMPLELOCK_LOCKED, __ATOMIC_ACQUIRE) == __SIMPLELOCK_LOCKED) {
86		/* do nothing */
87	}
88}
89
90static __inline int __unused
91__cpu_simple_lock_try(__cpu_simple_lock_t *__ptr)
92{
93	return __atomic_exchange_n(__ptr, __SIMPLELOCK_LOCKED, __ATOMIC_ACQUIRE) == __SIMPLELOCK_UNLOCKED;
94}
95
96static __inline void __unused
97__cpu_simple_unlock(__cpu_simple_lock_t *__ptr)
98{
99	__atomic_store_n(__ptr, __SIMPLELOCK_UNLOCKED, __ATOMIC_RELEASE);
100}
101
102#endif /* _SYS_COMMON_LOCK_H_ */
103