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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#include <asm/barrier.h>
20
21/*
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
38#ifdef CONFIG_SMP
39
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#define ATOMIC_FETCH_OP(op, c_op) \
65static inline int atomic_fetch_##op(int i, atomic_t *v) \
66{ \
67 int c, old; \
68 \
69 c = v->counter; \
70 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
71 c = old; \
72 \
73 return c; \
74}
75
76#else
77
78#include <linux/irqflags.h>
79
80#define ATOMIC_OP(op, c_op) \
81static inline void atomic_##op(int i, atomic_t *v) \
82{ \
83 unsigned long flags; \
84 \
85 raw_local_irq_save(flags); \
86 v->counter = v->counter c_op i; \
87 raw_local_irq_restore(flags); \
88}
89
90#define ATOMIC_OP_RETURN(op, c_op) \
91static inline int atomic_##op##_return(int i, atomic_t *v) \
92{ \
93 unsigned long flags; \
94 int ret; \
95 \
96 raw_local_irq_save(flags); \
97 ret = (v->counter = v->counter c_op i); \
98 raw_local_irq_restore(flags); \
99 \
100 return ret; \
101}
102
103#define ATOMIC_FETCH_OP(op, c_op) \
104static inline int atomic_fetch_##op(int i, atomic_t *v) \
105{ \
106 unsigned long flags; \
107 int ret; \
108 \
109 raw_local_irq_save(flags); \
110 ret = v->counter; \
111 v->counter = v->counter c_op i; \
112 raw_local_irq_restore(flags); \
113 \
114 return ret; \
115}
116
117#endif /* CONFIG_SMP */
118
119#ifndef atomic_add_return
120ATOMIC_OP_RETURN(add, +)
121#endif
122
123#ifndef atomic_sub_return
124ATOMIC_OP_RETURN(sub, -)
125#endif
126
127#ifndef atomic_fetch_add
128ATOMIC_FETCH_OP(add, +)
129#endif
130
131#ifndef atomic_fetch_sub
132ATOMIC_FETCH_OP(sub, -)
133#endif
134
135#ifndef atomic_fetch_and
136ATOMIC_FETCH_OP(and, &)
137#endif
138
139#ifndef atomic_fetch_or
140ATOMIC_FETCH_OP(or, |)
141#endif
142
143#ifndef atomic_fetch_xor
144ATOMIC_FETCH_OP(xor, ^)
145#endif
146
147#ifndef atomic_and
148ATOMIC_OP(and, &)
149#endif
150
151#ifndef atomic_or
152ATOMIC_OP(or, |)
153#endif
154
155#ifndef atomic_xor
156ATOMIC_OP(xor, ^)
157#endif
158
159#undef ATOMIC_FETCH_OP
160#undef ATOMIC_OP_RETURN
161#undef ATOMIC_OP
162
163/*
164 * Atomic operations that C can't guarantee us. Useful for
165 * resource counting etc..
166 */
167
168#define ATOMIC_INIT(i) { (i) }
169
170/**
171 * atomic_read - read atomic variable
172 * @v: pointer of type atomic_t
173 *
174 * Atomically reads the value of @v.
175 */
176#ifndef atomic_read
177#define atomic_read(v) READ_ONCE((v)->counter)
178#endif
179
180/**
181 * atomic_set - set atomic variable
182 * @v: pointer of type atomic_t
183 * @i: required value
184 *
185 * Atomically sets the value of @v to @i.
186 */
187#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
188
189#include <linux/irqflags.h>
190
191static inline int atomic_add_negative(int i, atomic_t *v)
192{
193 return atomic_add_return(i, v) < 0;
194}
195
196static inline void atomic_add(int i, atomic_t *v)
197{
198 atomic_add_return(i, v);
199}
200
201static inline void atomic_sub(int i, atomic_t *v)
202{
203 atomic_sub_return(i, v);
204}
205
206static inline void atomic_inc(atomic_t *v)
207{
208 atomic_add_return(1, v);
209}
210
211static inline void atomic_dec(atomic_t *v)
212{
213 atomic_sub_return(1, v);
214}
215
216#define atomic_dec_return(v) atomic_sub_return(1, (v))
217#define atomic_inc_return(v) atomic_add_return(1, (v))
218
219#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
220#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
221#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
222
223#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
224#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
225
226static inline int __atomic_add_unless(atomic_t *v, int a, int u)
227{
228 int c, old;
229 c = atomic_read(v);
230 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
231 c = old;
232 return c;
233}
234
235#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 */