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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 | ||
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 | |
66 | static 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 | |
89 | static 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 | ||
104 | static inline int atomic_add_negative(int i, atomic_t *v) | |
105 | { | |
106 | return atomic_add_return(i, v) < 0; | |
107 | } | |
108 | ||
109 | static inline void atomic_add(int i, atomic_t *v) | |
110 | { | |
111 | atomic_add_return(i, v); | |
112 | } | |
113 | ||
114 | static inline void atomic_sub(int i, atomic_t *v) | |
115 | { | |
116 | atomic_sub_return(i, v); | |
117 | } | |
118 | ||
119 | static inline void atomic_inc(atomic_t *v) | |
120 | { | |
121 | atomic_add_return(1, v); | |
122 | } | |
123 | ||
124 | static 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 | ||
139 | static 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 | |
156 | static 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 | |
175 | static 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 */ |