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Arnd Bergmann3f7e212d2009-05-13 22:56:35 +00001/*
Arun Sharmaacac43e2011-07-26 16:09:08 -07002 * Generic C implementation of atomic counter operations. Usable on
3 * UP systems only. Do not include in machine independent code.
4 *
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +00005 * Originally implemented for MN10300.
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_ATOMIC_H
16#define __ASM_GENERIC_ATOMIC_H
17
David Howells34484272012-03-28 18:30:03 +010018#include <asm/cmpxchg.h>
Peter Zijlstrafebdbfe2014-02-06 18:16:07 +010019#include <asm/barrier.h>
David Howells34484272012-03-28 18:30:03 +010020
Peter Zijlstra560cb122014-04-23 16:12:30 +020021/*
22 * atomic_$op() - $op integer to atomic variable
23 * @i: integer value to $op
24 * @v: pointer to the atomic variable
25 *
26 * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use
27 * smp_mb__{before,after}_atomic().
28 */
29
30/*
31 * atomic_$op_return() - $op interer to atomic variable and returns the result
32 * @i: integer value to $op
33 * @v: pointer to the atomic variable
34 *
35 * Atomically $ops @i to @v. Does imply a full memory barrier.
36 */
37
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +000038#ifdef CONFIG_SMP
Peter Zijlstra560cb122014-04-23 16:12:30 +020039
40/* we can build all atomic primitives from cmpxchg */
41
42#define ATOMIC_OP(op, c_op) \
43static inline void atomic_##op(int i, atomic_t *v) \
44{ \
45 int c, old; \
46 \
47 c = v->counter; \
48 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
49 c = old; \
50}
51
52#define ATOMIC_OP_RETURN(op, c_op) \
53static inline int atomic_##op##_return(int i, atomic_t *v) \
54{ \
55 int c, old; \
56 \
57 c = v->counter; \
58 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
59 c = old; \
60 \
61 return c c_op i; \
62}
63
64#else
65
66#include <linux/irqflags.h>
67
68#define ATOMIC_OP(op, c_op) \
69static inline void atomic_##op(int i, atomic_t *v) \
70{ \
71 unsigned long flags; \
72 \
73 raw_local_irq_save(flags); \
74 v->counter = v->counter c_op i; \
75 raw_local_irq_restore(flags); \
76}
77
78#define ATOMIC_OP_RETURN(op, c_op) \
79static inline int atomic_##op##_return(int i, atomic_t *v) \
80{ \
81 unsigned long flags; \
82 int ret; \
83 \
84 raw_local_irq_save(flags); \
85 ret = (v->counter = v->counter c_op i); \
86 raw_local_irq_restore(flags); \
87 \
88 return ret; \
89}
90
91#endif /* CONFIG_SMP */
92
93#ifndef atomic_add_return
94ATOMIC_OP_RETURN(add, +)
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +000095#endif
96
Peter Zijlstra560cb122014-04-23 16:12:30 +020097#ifndef atomic_sub_return
98ATOMIC_OP_RETURN(sub, -)
99#endif
100
Peter Zijlstra56d1def2015-07-15 15:47:25 +0200101#ifndef atomic_and
Peter Zijlstra560cb122014-04-23 16:12:30 +0200102ATOMIC_OP(and, &)
Peter Zijlstra56d1def2015-07-15 15:47:25 +0200103#endif
104
Peter Zijlstra56d1def2015-07-15 15:47:25 +0200105#ifndef atomic_or
Peter Zijlstra560cb122014-04-23 16:12:30 +0200106ATOMIC_OP(or, |)
Peter Zijlstra56d1def2015-07-15 15:47:25 +0200107#endif
108
Peter Zijlstrae6942b72014-04-23 19:32:50 +0200109#ifndef atomic_xor
110ATOMIC_OP(xor, ^)
Peter Zijlstra560cb122014-04-23 16:12:30 +0200111#endif
112
113#undef ATOMIC_OP_RETURN
114#undef ATOMIC_OP
115
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000116/*
117 * Atomic operations that C can't guarantee us. Useful for
118 * resource counting etc..
119 */
120
121#define ATOMIC_INIT(i) { (i) }
122
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000123/**
124 * atomic_read - read atomic variable
125 * @v: pointer of type atomic_t
126 *
Peter Fritzsche37682172010-05-24 14:33:09 -0700127 * Atomically reads the value of @v.
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000128 */
Mike Frysinger7505cb62011-07-26 16:09:11 -0700129#ifndef atomic_read
Peter Zijlstra62e8a322015-09-18 11:13:10 +0200130#define atomic_read(v) READ_ONCE((v)->counter)
Mike Frysinger7505cb62011-07-26 16:09:11 -0700131#endif
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000132
133/**
134 * atomic_set - set atomic variable
135 * @v: pointer of type atomic_t
136 * @i: required value
137 *
Peter Fritzsche37682172010-05-24 14:33:09 -0700138 * Atomically sets the value of @v to @i.
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000139 */
Peter Zijlstra62e8a322015-09-18 11:13:10 +0200140#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000141
David Howellsdf9ee292010-10-07 14:08:55 +0100142#include <linux/irqflags.h>
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000143
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000144static inline int atomic_add_negative(int i, atomic_t *v)
145{
146 return atomic_add_return(i, v) < 0;
147}
148
149static inline void atomic_add(int i, atomic_t *v)
150{
151 atomic_add_return(i, v);
152}
153
154static inline void atomic_sub(int i, atomic_t *v)
155{
156 atomic_sub_return(i, v);
157}
158
159static inline void atomic_inc(atomic_t *v)
160{
161 atomic_add_return(1, v);
162}
163
164static inline void atomic_dec(atomic_t *v)
165{
166 atomic_sub_return(1, v);
167}
168
169#define atomic_dec_return(v) atomic_sub_return(1, (v))
170#define atomic_inc_return(v) atomic_add_return(1, (v))
171
172#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
Mike Frysinger3eea44e2011-07-26 16:09:09 -0700173#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
174#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000175
Mathieu Lacage8b9d4062010-06-27 12:26:06 +0200176#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
177#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
178
Arun Sharmaf24219b2011-07-26 16:09:07 -0700179static inline int __atomic_add_unless(atomic_t *v, int a, int u)
Mathieu Lacage8b9d4062010-06-27 12:26:06 +0200180{
Peter Zijlstra560cb122014-04-23 16:12:30 +0200181 int c, old;
182 c = atomic_read(v);
183 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
184 c = old;
185 return c;
Mathieu Lacage8b9d4062010-06-27 12:26:06 +0200186}
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000187
Arnd Bergmann3f7e212d2009-05-13 22:56:35 +0000188#endif /* __ASM_GENERIC_ATOMIC_H */