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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Generic C implementation of atomic counter operations. Usable on
4 * UP systems only. Do not include in 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/*
16 * atomic_$op() - $op integer to atomic variable
17 * @i: integer value to $op
18 * @v: pointer to the atomic variable
19 *
20 * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use
21 * smp_mb__{before,after}_atomic().
22 */
23
24/*
25 * atomic_$op_return() - $op interer to atomic variable and returns the result
26 * @i: integer value to $op
27 * @v: pointer to the atomic variable
28 *
29 * Atomically $ops @i to @v. Does imply a full memory barrier.
30 */
31
32#ifdef CONFIG_SMP
33
34/* we can build all atomic primitives from cmpxchg */
35
36#define ATOMIC_OP(op, c_op) \
37static inline void atomic_##op(int i, atomic_t *v) \
38{ \
39 int c, old; \
40 \
41 c = v->counter; \
42 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
43 c = old; \
44}
45
46#define ATOMIC_OP_RETURN(op, c_op) \
47static inline int atomic_##op##_return(int i, atomic_t *v) \
48{ \
49 int c, old; \
50 \
51 c = v->counter; \
52 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
53 c = old; \
54 \
55 return c c_op i; \
56}
57
58#define ATOMIC_FETCH_OP(op, c_op) \
59static inline int atomic_fetch_##op(int i, atomic_t *v) \
60{ \
61 int c, old; \
62 \
63 c = v->counter; \
64 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
65 c = old; \
66 \
67 return c; \
68}
69
70#else
71
72#include <linux/irqflags.h>
73
74#define ATOMIC_OP(op, c_op) \
75static inline void atomic_##op(int i, atomic_t *v) \
76{ \
77 unsigned long flags; \
78 \
79 raw_local_irq_save(flags); \
80 v->counter = v->counter c_op i; \
81 raw_local_irq_restore(flags); \
82}
83
84#define ATOMIC_OP_RETURN(op, c_op) \
85static inline int atomic_##op##_return(int i, atomic_t *v) \
86{ \
87 unsigned long flags; \
88 int ret; \
89 \
90 raw_local_irq_save(flags); \
91 ret = (v->counter = v->counter c_op i); \
92 raw_local_irq_restore(flags); \
93 \
94 return ret; \
95}
96
97#define ATOMIC_FETCH_OP(op, c_op) \
98static inline int atomic_fetch_##op(int i, atomic_t *v) \
99{ \
100 unsigned long flags; \
101 int ret; \
102 \
103 raw_local_irq_save(flags); \
104 ret = v->counter; \
105 v->counter = v->counter c_op i; \
106 raw_local_irq_restore(flags); \
107 \
108 return ret; \
109}
110
111#endif /* CONFIG_SMP */
112
113#ifndef atomic_add_return
114ATOMIC_OP_RETURN(add, +)
115#endif
116
117#ifndef atomic_sub_return
118ATOMIC_OP_RETURN(sub, -)
119#endif
120
121#ifndef atomic_fetch_add
122ATOMIC_FETCH_OP(add, +)
123#endif
124
125#ifndef atomic_fetch_sub
126ATOMIC_FETCH_OP(sub, -)
127#endif
128
129#ifndef atomic_fetch_and
130ATOMIC_FETCH_OP(and, &)
131#endif
132
133#ifndef atomic_fetch_or
134ATOMIC_FETCH_OP(or, |)
135#endif
136
137#ifndef atomic_fetch_xor
138ATOMIC_FETCH_OP(xor, ^)
139#endif
140
141#ifndef atomic_and
142ATOMIC_OP(and, &)
143#endif
144
145#ifndef atomic_or
146ATOMIC_OP(or, |)
147#endif
148
149#ifndef atomic_xor
150ATOMIC_OP(xor, ^)
151#endif
152
153#undef ATOMIC_FETCH_OP
154#undef ATOMIC_OP_RETURN
155#undef ATOMIC_OP
156
157/*
158 * Atomic operations that C can't guarantee us. Useful for
159 * resource counting etc..
160 */
161
162#define ATOMIC_INIT(i) { (i) }
163
164/**
165 * atomic_read - read atomic variable
166 * @v: pointer of type atomic_t
167 *
168 * Atomically reads the value of @v.
169 */
170#ifndef atomic_read
171#define atomic_read(v) READ_ONCE((v)->counter)
172#endif
173
174/**
175 * atomic_set - set atomic variable
176 * @v: pointer of type atomic_t
177 * @i: required value
178 *
179 * Atomically sets the value of @v to @i.
180 */
181#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
182
183#include <linux/irqflags.h>
184
185static inline void atomic_add(int i, atomic_t *v)
186{
187 atomic_add_return(i, v);
188}
189
190static inline void atomic_sub(int i, atomic_t *v)
191{
192 atomic_sub_return(i, v);
193}
194
195#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
196#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
197
198#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#ifdef CONFIG_SMP
19/* Force people to define core atomics */
20# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \
21 !defined(atomic_clear_mask) || !defined(atomic_set_mask)
22# error "SMP requires a little arch-specific magic"
23# endif
24#endif
25
26/*
27 * Atomic operations that C can't guarantee us. Useful for
28 * resource counting etc..
29 */
30
31#define ATOMIC_INIT(i) { (i) }
32
33#ifdef __KERNEL__
34
35/**
36 * atomic_read - read atomic variable
37 * @v: pointer of type atomic_t
38 *
39 * Atomically reads the value of @v.
40 */
41#ifndef atomic_read
42#define atomic_read(v) (*(volatile int *)&(v)->counter)
43#endif
44
45/**
46 * atomic_set - set atomic variable
47 * @v: pointer of type atomic_t
48 * @i: required value
49 *
50 * Atomically sets the value of @v to @i.
51 */
52#define atomic_set(v, i) (((v)->counter) = (i))
53
54#include <linux/irqflags.h>
55#include <asm/system.h>
56
57/**
58 * atomic_add_return - add integer to atomic variable
59 * @i: integer value to add
60 * @v: pointer of type atomic_t
61 *
62 * Atomically adds @i to @v and returns the result
63 */
64#ifndef atomic_add_return
65static inline int atomic_add_return(int i, atomic_t *v)
66{
67 unsigned long flags;
68 int temp;
69
70 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
71 temp = v->counter;
72 temp += i;
73 v->counter = temp;
74 raw_local_irq_restore(flags);
75
76 return temp;
77}
78#endif
79
80/**
81 * atomic_sub_return - subtract integer from atomic variable
82 * @i: integer value to subtract
83 * @v: pointer of type atomic_t
84 *
85 * Atomically subtracts @i from @v and returns the result
86 */
87#ifndef atomic_sub_return
88static inline int atomic_sub_return(int i, atomic_t *v)
89{
90 unsigned long flags;
91 int temp;
92
93 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
94 temp = v->counter;
95 temp -= i;
96 v->counter = temp;
97 raw_local_irq_restore(flags);
98
99 return temp;
100}
101#endif
102
103static inline int atomic_add_negative(int i, atomic_t *v)
104{
105 return atomic_add_return(i, v) < 0;
106}
107
108static inline void atomic_add(int i, atomic_t *v)
109{
110 atomic_add_return(i, v);
111}
112
113static inline void atomic_sub(int i, atomic_t *v)
114{
115 atomic_sub_return(i, v);
116}
117
118static inline void atomic_inc(atomic_t *v)
119{
120 atomic_add_return(1, v);
121}
122
123static inline void atomic_dec(atomic_t *v)
124{
125 atomic_sub_return(1, v);
126}
127
128#define atomic_dec_return(v) atomic_sub_return(1, (v))
129#define atomic_inc_return(v) atomic_add_return(1, (v))
130
131#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
132#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
133#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
134
135#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
136#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
137
138#define cmpxchg_local(ptr, o, n) \
139 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
140 (unsigned long)(n), sizeof(*(ptr))))
141
142#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
143
144static inline int __atomic_add_unless(atomic_t *v, int a, int u)
145{
146 int c, old;
147 c = atomic_read(v);
148 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
149 c = old;
150 return c;
151}
152
153/**
154 * atomic_clear_mask - Atomically clear bits in atomic variable
155 * @mask: Mask of the bits to be cleared
156 * @v: pointer of type atomic_t
157 *
158 * Atomically clears the bits set in @mask from @v
159 */
160#ifndef atomic_clear_mask
161static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
162{
163 unsigned long flags;
164
165 mask = ~mask;
166 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
167 v->counter &= mask;
168 raw_local_irq_restore(flags);
169}
170#endif
171
172/**
173 * atomic_set_mask - Atomically set bits in atomic variable
174 * @mask: Mask of the bits to be set
175 * @v: pointer of type atomic_t
176 *
177 * Atomically sets the bits set in @mask in @v
178 */
179#ifndef atomic_set_mask
180static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
181{
182 unsigned long flags;
183
184 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
185 v->counter |= mask;
186 raw_local_irq_restore(flags);
187}
188#endif
189
190/* Assume that atomic operations are already serializing */
191#define smp_mb__before_atomic_dec() barrier()
192#define smp_mb__after_atomic_dec() barrier()
193#define smp_mb__before_atomic_inc() barrier()
194#define smp_mb__after_atomic_inc() barrier()
195
196#endif /* __KERNEL__ */
197#endif /* __ASM_GENERIC_ATOMIC_H */