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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Generic C implementation of atomic counter operations. Do not include in
4 * machine independent code.
5 *
6 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
7 * Written by David Howells (dhowells@redhat.com)
8 */
9#ifndef __ASM_GENERIC_ATOMIC_H
10#define __ASM_GENERIC_ATOMIC_H
11
12#include <asm/cmpxchg.h>
13#include <asm/barrier.h>
14
15#ifdef CONFIG_SMP
16
17/* we can build all atomic primitives from cmpxchg */
18
19#define ATOMIC_OP(op, c_op) \
20static inline void generic_atomic_##op(int i, atomic_t *v) \
21{ \
22 int c, old; \
23 \
24 c = v->counter; \
25 while ((old = arch_cmpxchg(&v->counter, c, c c_op i)) != c) \
26 c = old; \
27}
28
29#define ATOMIC_OP_RETURN(op, c_op) \
30static inline int generic_atomic_##op##_return(int i, atomic_t *v) \
31{ \
32 int c, old; \
33 \
34 c = v->counter; \
35 while ((old = arch_cmpxchg(&v->counter, c, c c_op i)) != c) \
36 c = old; \
37 \
38 return c c_op i; \
39}
40
41#define ATOMIC_FETCH_OP(op, c_op) \
42static inline int generic_atomic_fetch_##op(int i, atomic_t *v) \
43{ \
44 int c, old; \
45 \
46 c = v->counter; \
47 while ((old = arch_cmpxchg(&v->counter, c, c c_op i)) != c) \
48 c = old; \
49 \
50 return c; \
51}
52
53#else
54
55#include <linux/irqflags.h>
56
57#define ATOMIC_OP(op, c_op) \
58static inline void generic_atomic_##op(int i, atomic_t *v) \
59{ \
60 unsigned long flags; \
61 \
62 raw_local_irq_save(flags); \
63 v->counter = v->counter c_op i; \
64 raw_local_irq_restore(flags); \
65}
66
67#define ATOMIC_OP_RETURN(op, c_op) \
68static inline int generic_atomic_##op##_return(int i, atomic_t *v) \
69{ \
70 unsigned long flags; \
71 int ret; \
72 \
73 raw_local_irq_save(flags); \
74 ret = (v->counter = v->counter c_op i); \
75 raw_local_irq_restore(flags); \
76 \
77 return ret; \
78}
79
80#define ATOMIC_FETCH_OP(op, c_op) \
81static inline int generic_atomic_fetch_##op(int i, atomic_t *v) \
82{ \
83 unsigned long flags; \
84 int ret; \
85 \
86 raw_local_irq_save(flags); \
87 ret = v->counter; \
88 v->counter = v->counter c_op i; \
89 raw_local_irq_restore(flags); \
90 \
91 return ret; \
92}
93
94#endif /* CONFIG_SMP */
95
96ATOMIC_OP_RETURN(add, +)
97ATOMIC_OP_RETURN(sub, -)
98
99ATOMIC_FETCH_OP(add, +)
100ATOMIC_FETCH_OP(sub, -)
101ATOMIC_FETCH_OP(and, &)
102ATOMIC_FETCH_OP(or, |)
103ATOMIC_FETCH_OP(xor, ^)
104
105ATOMIC_OP(add, +)
106ATOMIC_OP(sub, -)
107ATOMIC_OP(and, &)
108ATOMIC_OP(or, |)
109ATOMIC_OP(xor, ^)
110
111#undef ATOMIC_FETCH_OP
112#undef ATOMIC_OP_RETURN
113#undef ATOMIC_OP
114
115#define arch_atomic_add_return generic_atomic_add_return
116#define arch_atomic_sub_return generic_atomic_sub_return
117
118#define arch_atomic_fetch_add generic_atomic_fetch_add
119#define arch_atomic_fetch_sub generic_atomic_fetch_sub
120#define arch_atomic_fetch_and generic_atomic_fetch_and
121#define arch_atomic_fetch_or generic_atomic_fetch_or
122#define arch_atomic_fetch_xor generic_atomic_fetch_xor
123
124#define arch_atomic_add generic_atomic_add
125#define arch_atomic_sub generic_atomic_sub
126#define arch_atomic_and generic_atomic_and
127#define arch_atomic_or generic_atomic_or
128#define arch_atomic_xor generic_atomic_xor
129
130#define arch_atomic_read(v) READ_ONCE((v)->counter)
131#define arch_atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
132
133#endif /* __ASM_GENERIC_ATOMIC_H */
1/*
2 * Generic C implementation of atomic counter operations. Usable on
3 * UP systems only. Do not include in machine independent code.
4 *
5 * 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
18#include <asm/cmpxchg.h>
19
20#ifdef CONFIG_SMP
21/* Force people to define core atomics */
22# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \
23 !defined(atomic_clear_mask) || !defined(atomic_set_mask)
24# error "SMP requires a little arch-specific magic"
25# endif
26#endif
27
28/*
29 * Atomic operations that C can't guarantee us. Useful for
30 * resource counting etc..
31 */
32
33#define ATOMIC_INIT(i) { (i) }
34
35#ifdef __KERNEL__
36
37/**
38 * atomic_read - read atomic variable
39 * @v: pointer of type atomic_t
40 *
41 * Atomically reads the value of @v.
42 */
43#ifndef atomic_read
44#define atomic_read(v) (*(volatile int *)&(v)->counter)
45#endif
46
47/**
48 * atomic_set - set atomic variable
49 * @v: pointer of type atomic_t
50 * @i: required value
51 *
52 * Atomically sets the value of @v to @i.
53 */
54#define atomic_set(v, i) (((v)->counter) = (i))
55
56#include <linux/irqflags.h>
57
58/**
59 * atomic_add_return - add integer to atomic variable
60 * @i: integer value to add
61 * @v: pointer of type atomic_t
62 *
63 * Atomically adds @i to @v and returns the result
64 */
65#ifndef atomic_add_return
66static inline int atomic_add_return(int i, atomic_t *v)
67{
68 unsigned long flags;
69 int temp;
70
71 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
72 temp = v->counter;
73 temp += i;
74 v->counter = temp;
75 raw_local_irq_restore(flags);
76
77 return temp;
78}
79#endif
80
81/**
82 * atomic_sub_return - subtract integer from atomic variable
83 * @i: integer value to subtract
84 * @v: pointer of type atomic_t
85 *
86 * Atomically subtracts @i from @v and returns the result
87 */
88#ifndef atomic_sub_return
89static inline int atomic_sub_return(int i, atomic_t *v)
90{
91 unsigned long flags;
92 int temp;
93
94 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
95 temp = v->counter;
96 temp -= i;
97 v->counter = temp;
98 raw_local_irq_restore(flags);
99
100 return temp;
101}
102#endif
103
104static inline int atomic_add_negative(int i, atomic_t *v)
105{
106 return atomic_add_return(i, v) < 0;
107}
108
109static inline void atomic_add(int i, atomic_t *v)
110{
111 atomic_add_return(i, v);
112}
113
114static inline void atomic_sub(int i, atomic_t *v)
115{
116 atomic_sub_return(i, v);
117}
118
119static inline void atomic_inc(atomic_t *v)
120{
121 atomic_add_return(1, v);
122}
123
124static inline void atomic_dec(atomic_t *v)
125{
126 atomic_sub_return(1, v);
127}
128
129#define atomic_dec_return(v) atomic_sub_return(1, (v))
130#define atomic_inc_return(v) atomic_add_return(1, (v))
131
132#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
133#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
134#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
135
136#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
137#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
138
139static inline int __atomic_add_unless(atomic_t *v, int a, int u)
140{
141 int c, old;
142 c = atomic_read(v);
143 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
144 c = old;
145 return c;
146}
147
148/**
149 * atomic_clear_mask - Atomically clear bits in atomic variable
150 * @mask: Mask of the bits to be cleared
151 * @v: pointer of type atomic_t
152 *
153 * Atomically clears the bits set in @mask from @v
154 */
155#ifndef atomic_clear_mask
156static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
157{
158 unsigned long flags;
159
160 mask = ~mask;
161 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
162 v->counter &= mask;
163 raw_local_irq_restore(flags);
164}
165#endif
166
167/**
168 * atomic_set_mask - Atomically set bits in atomic variable
169 * @mask: Mask of the bits to be set
170 * @v: pointer of type atomic_t
171 *
172 * Atomically sets the bits set in @mask in @v
173 */
174#ifndef atomic_set_mask
175static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
176{
177 unsigned long flags;
178
179 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
180 v->counter |= mask;
181 raw_local_irq_restore(flags);
182}
183#endif
184
185/* Assume that atomic operations are already serializing */
186#define smp_mb__before_atomic_dec() barrier()
187#define smp_mb__after_atomic_dec() barrier()
188#define smp_mb__before_atomic_inc() barrier()
189#define smp_mb__after_atomic_inc() barrier()
190
191#endif /* __KERNEL__ */
192#endif /* __ASM_GENERIC_ATOMIC_H */