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1 | /* | |
2 | * Generic C implementation of atomic counter operations | |
3 | * Originally implemented for MN10300. | |
4 | * | |
5 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | |
6 | * Written by David Howells (dhowells@redhat.com) | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public Licence | |
10 | * as published by the Free Software Foundation; either version | |
11 | * 2 of the Licence, or (at your option) any later version. | |
12 | */ | |
13 | #ifndef __ASM_GENERIC_ATOMIC_H | |
14 | #define __ASM_GENERIC_ATOMIC_H | |
15 | ||
16 | #ifdef CONFIG_SMP | |
17 | #error not SMP safe | |
18 | #endif | |
19 | ||
20 | /* | |
21 | * Atomic operations that C can't guarantee us. Useful for | |
22 | * resource counting etc.. | |
23 | */ | |
24 | ||
25 | #define ATOMIC_INIT(i) { (i) } | |
26 | ||
27 | #ifdef __KERNEL__ | |
28 | ||
29 | /** | |
30 | * atomic_read - read atomic variable | |
31 | * @v: pointer of type atomic_t | |
32 | * | |
33 | * Atomically reads the value of @v. | |
34 | */ | |
35 | #define atomic_read(v) (*(volatile int *)&(v)->counter) | |
36 | ||
37 | /** | |
38 | * atomic_set - set atomic variable | |
39 | * @v: pointer of type atomic_t | |
40 | * @i: required value | |
41 | * | |
42 | * Atomically sets the value of @v to @i. | |
43 | */ | |
44 | #define atomic_set(v, i) (((v)->counter) = (i)) | |
45 | ||
46 | #include <asm/system.h> | |
47 | ||
48 | /** | |
49 | * atomic_add_return - add integer to atomic variable | |
50 | * @i: integer value to add | |
51 | * @v: pointer of type atomic_t | |
52 | * | |
53 | * Atomically adds @i to @v and returns the result | |
54 | */ | |
55 | static inline int atomic_add_return(int i, atomic_t *v) | |
56 | { | |
57 | unsigned long flags; | |
58 | int temp; | |
59 | ||
60 | raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ | |
61 | temp = v->counter; | |
62 | temp += i; | |
63 | v->counter = temp; | |
64 | raw_local_irq_restore(flags); | |
65 | ||
66 | return temp; | |
67 | } | |
68 | ||
69 | /** | |
70 | * atomic_sub_return - subtract integer from atomic variable | |
71 | * @i: integer value to subtract | |
72 | * @v: pointer of type atomic_t | |
73 | * | |
74 | * Atomically subtracts @i from @v and returns the result | |
75 | */ | |
76 | static inline int atomic_sub_return(int i, atomic_t *v) | |
77 | { | |
78 | unsigned long flags; | |
79 | int temp; | |
80 | ||
81 | raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ | |
82 | temp = v->counter; | |
83 | temp -= i; | |
84 | v->counter = temp; | |
85 | raw_local_irq_restore(flags); | |
86 | ||
87 | return temp; | |
88 | } | |
89 | ||
90 | static inline int atomic_add_negative(int i, atomic_t *v) | |
91 | { | |
92 | return atomic_add_return(i, v) < 0; | |
93 | } | |
94 | ||
95 | static inline void atomic_add(int i, atomic_t *v) | |
96 | { | |
97 | atomic_add_return(i, v); | |
98 | } | |
99 | ||
100 | static inline void atomic_sub(int i, atomic_t *v) | |
101 | { | |
102 | atomic_sub_return(i, v); | |
103 | } | |
104 | ||
105 | static inline void atomic_inc(atomic_t *v) | |
106 | { | |
107 | atomic_add_return(1, v); | |
108 | } | |
109 | ||
110 | static inline void atomic_dec(atomic_t *v) | |
111 | { | |
112 | atomic_sub_return(1, v); | |
113 | } | |
114 | ||
115 | #define atomic_dec_return(v) atomic_sub_return(1, (v)) | |
116 | #define atomic_inc_return(v) atomic_add_return(1, (v)) | |
117 | ||
118 | #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) | |
119 | #define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0) | |
120 | #define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0) | |
121 | ||
122 | #define atomic_add_unless(v, a, u) \ | |
123 | ({ \ | |
124 | int c, old; \ | |
125 | c = atomic_read(v); \ | |
126 | while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ | |
127 | c = old; \ | |
128 | c != (u); \ | |
129 | }) | |
130 | ||
131 | #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) | |
132 | ||
133 | static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) | |
134 | { | |
135 | unsigned long flags; | |
136 | ||
137 | mask = ~mask; | |
138 | raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ | |
139 | *addr &= mask; | |
140 | raw_local_irq_restore(flags); | |
141 | } | |
142 | ||
143 | #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) | |
144 | #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) | |
145 | ||
146 | #define cmpxchg_local(ptr, o, n) \ | |
147 | ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ | |
148 | (unsigned long)(n), sizeof(*(ptr)))) | |
149 | ||
150 | #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) | |
151 | ||
152 | /* Assume that atomic operations are already serializing */ | |
153 | #define smp_mb__before_atomic_dec() barrier() | |
154 | #define smp_mb__after_atomic_dec() barrier() | |
155 | #define smp_mb__before_atomic_inc() barrier() | |
156 | #define smp_mb__after_atomic_inc() barrier() | |
157 | ||
158 | #include <asm-generic/atomic-long.h> | |
159 | ||
160 | #endif /* __KERNEL__ */ | |
161 | #endif /* __ASM_GENERIC_ATOMIC_H */ |