aboutsummaryrefslogtreecommitdiffstats
path: root/include/asm-generic/atomic.h
blob: 33bd2de3bc1e930da34dcb8b6007825807ddacb3 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
/*
 * Generic C implementation of atomic counter operations. Usable on
 * UP systems only. Do not include in machine independent code.
 *
 * Originally implemented for MN10300.
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#ifndef __ASM_GENERIC_ATOMIC_H
#define __ASM_GENERIC_ATOMIC_H

#include <asm/cmpxchg.h>

#ifdef CONFIG_SMP
/* Force people to define core atomics */
# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \
     !defined(atomic_clear_mask) || !defined(atomic_set_mask)
#  error "SMP requires a little arch-specific magic"
# endif
#endif

/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 */

#define ATOMIC_INIT(i)	{ (i) }

#ifdef __KERNEL__

/**
 * atomic_read - read atomic variable
 * @v: pointer of type atomic_t
 *
 * Atomically reads the value of @v.
 */
#ifndef atomic_read
#define atomic_read(v)	(*(volatile int *)&(v)->counter)
#endif

/**
 * atomic_set - set atomic variable
 * @v: pointer of type atomic_t
 * @i: required value
 *
 * Atomically sets the value of @v to @i.
 */
#define atomic_set(v, i) (((v)->counter) = (i))

#include <linux/irqflags.h>

/**
 * atomic_add_return - add integer to atomic variable
 * @i: integer value to add
 * @v: pointer of type atomic_t
 *
 * Atomically adds @i to @v and returns the result
 */
#ifndef atomic_add_return
static inline int atomic_add_return(int i, atomic_t *v)
{
	unsigned long flags;
	int temp;

	raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
	temp = v->counter;
	temp += i;
	v->counter = temp;
	raw_local_irq_restore(flags);

	return temp;
}
#endif

/**
 * atomic_sub_return - subtract integer from atomic variable
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 *
 * Atomically subtracts @i from @v and returns the result
 */
#ifndef atomic_sub_return
static inline int atomic_sub_return(int i, atomic_t *v)
{
	unsigned long flags;
	int temp;

	raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
	temp = v->counter;
	temp -= i;
	v->counter = temp;
	raw_local_irq_restore(flags);

	return temp;
}
#endif

static inline int atomic_add_negative(int i, atomic_t *v)
{
	return atomic_add_return(i, v) < 0;
}

static inline void atomic_add(int i, atomic_t *v)
{
	atomic_add_return(i, v);
}

static inline void atomic_sub(int i, atomic_t *v)
{
	atomic_sub_return(i, v);
}

static inline void atomic_inc(atomic_t *v)
{
	atomic_add_return(1, v);
}

static inline void atomic_dec(atomic_t *v)
{
	atomic_sub_return(1, v);
}

#define atomic_dec_return(v)		atomic_sub_return(1, (v))
#define atomic_inc_return(v)		atomic_add_return(1, (v))

#define atomic_sub_and_test(i, v)	(atomic_sub_return((i), (v)) == 0)
#define atomic_dec_and_test(v)		(atomic_dec_return(v) == 0)
#define atomic_inc_and_test(v)		(atomic_inc_return(v) == 0)

#define atomic_xchg(ptr, v)		(xchg(&(ptr)->counter, (v)))
#define atomic_cmpxchg(v, old, new)	(cmpxchg(&((v)->counter), (old), (new)))

static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
  int c, old;
  c = atomic_read(v);
  while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
    c = old;
  return c;
}

/**
 * atomic_clear_mask - Atomically clear bits in atomic variable
 * @mask: Mask of the bits to be cleared
 * @v: pointer of type atomic_t
 *
 * Atomically clears the bits set in @mask from @v
 */
#ifndef atomic_clear_mask
static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
{
	unsigned long flags;

	mask = ~mask;
	raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
	v->counter &= mask;
	raw_local_irq_restore(flags);
}
#endif

/**
 * atomic_set_mask - Atomically set bits in atomic variable
 * @mask: Mask of the bits to be set
 * @v: pointer of type atomic_t
 *
 * Atomically sets the bits set in @mask in @v
 */
#ifndef atomic_set_mask
static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
{
	unsigned long flags;

	raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
	v->counter |= mask;
	raw_local_irq_restore(flags);
}
#endif

/* Assume that atomic operations are already serializing */
#define smp_mb__before_atomic_dec()	barrier()
#define smp_mb__after_atomic_dec()	barrier()
#define smp_mb__before_atomic_inc()	barrier()
#define smp_mb__after_atomic_inc()	barrier()

#endif /* __KERNEL__ */
#endif /* __ASM_GENERIC_ATOMIC_H */