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
40 static __inline int
__SIMPLELOCK_LOCKED_P(const __cpu_simple_lock_t * __ptr)41 __SIMPLELOCK_LOCKED_P(const __cpu_simple_lock_t *__ptr)
42 {
43 return *__ptr != __SIMPLELOCK_UNLOCKED;
44 }
45
46 static __inline int
__SIMPLELOCK_UNLOCKED_P(const __cpu_simple_lock_t * __ptr)47 __SIMPLELOCK_UNLOCKED_P(const __cpu_simple_lock_t *__ptr)
48 {
49 return *__ptr == __SIMPLELOCK_UNLOCKED;
50 }
51
52 static __inline void
__cpu_simple_lock_clear(__cpu_simple_lock_t * __ptr)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
62 static __inline void
__cpu_simple_lock_set(__cpu_simple_lock_t * __ptr)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
72 static __inline void __unused
__cpu_simple_lock_init(__cpu_simple_lock_t * __ptr)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
82 static __inline void __unused
__cpu_simple_lock(__cpu_simple_lock_t * __ptr)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
90 static __inline int __unused
__cpu_simple_lock_try(__cpu_simple_lock_t * __ptr)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
96 static __inline void __unused
__cpu_simple_unlock(__cpu_simple_lock_t * __ptr)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