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1/*
2 * Generic barrier definitions, originally based on MN10300 definitions.
3 *
4 * It should be possible to use these on really simple architectures,
5 * but it serves more as a starting point for new ports.
6 *
7 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
8 * Written by David Howells (dhowells@redhat.com)
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public Licence
12 * as published by the Free Software Foundation; either version
13 * 2 of the Licence, or (at your option) any later version.
14 */
15#ifndef __ASM_GENERIC_BARRIER_H
16#define __ASM_GENERIC_BARRIER_H
17
18#ifndef __ASSEMBLY__
19
20#include <linux/compiler.h>
21
22#ifndef nop
23#define nop() asm volatile ("nop")
24#endif
25
26/*
27 * Force strict CPU ordering. And yes, this is required on UP too when we're
28 * talking to devices.
29 *
30 * Fall back to compiler barriers if nothing better is provided.
31 */
32
33#ifndef mb
34#define mb() barrier()
35#endif
36
37#ifndef rmb
38#define rmb() mb()
39#endif
40
41#ifndef wmb
42#define wmb() mb()
43#endif
44
45#ifndef dma_rmb
46#define dma_rmb() rmb()
47#endif
48
49#ifndef dma_wmb
50#define dma_wmb() wmb()
51#endif
52
53#ifndef read_barrier_depends
54#define read_barrier_depends() do { } while (0)
55#endif
56
57#ifdef CONFIG_SMP
58
59#ifndef smp_mb
60#define smp_mb() mb()
61#endif
62
63#ifndef smp_rmb
64#define smp_rmb() rmb()
65#endif
66
67#ifndef smp_wmb
68#define smp_wmb() wmb()
69#endif
70
71#ifndef smp_read_barrier_depends
72#define smp_read_barrier_depends() read_barrier_depends()
73#endif
74
75#else /* !CONFIG_SMP */
76
77#ifndef smp_mb
78#define smp_mb() barrier()
79#endif
80
81#ifndef smp_rmb
82#define smp_rmb() barrier()
83#endif
84
85#ifndef smp_wmb
86#define smp_wmb() barrier()
87#endif
88
89#ifndef smp_read_barrier_depends
90#define smp_read_barrier_depends() do { } while (0)
91#endif
92
93#endif /* CONFIG_SMP */
94
95#ifndef smp_store_mb
96#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); mb(); } while (0)
97#endif
98
99#ifndef smp_mb__before_atomic
100#define smp_mb__before_atomic() smp_mb()
101#endif
102
103#ifndef smp_mb__after_atomic
104#define smp_mb__after_atomic() smp_mb()
105#endif
106
107#define smp_store_release(p, v) \
108do { \
109 compiletime_assert_atomic_type(*p); \
110 smp_mb(); \
111 WRITE_ONCE(*p, v); \
112} while (0)
113
114#define smp_load_acquire(p) \
115({ \
116 typeof(*p) ___p1 = READ_ONCE(*p); \
117 compiletime_assert_atomic_type(*p); \
118 smp_mb(); \
119 ___p1; \
120})
121
122#endif /* !__ASSEMBLY__ */
123#endif /* __ASM_GENERIC_BARRIER_H */