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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 <linux/irqflags.h> |
47 | #include <asm/system.h> |
48 | |
49 | /** |
50 | * atomic_add_return - add integer to atomic variable |
51 | * @i: integer value to add |
52 | * @v: pointer of type atomic_t |
53 | * |
54 | * Atomically adds @i to @v and returns the result |
55 | */ |
56 | static inline int atomic_add_return(int i, atomic_t *v) |
57 | { |
58 | unsigned long flags; |
59 | int temp; |
60 | |
61 | raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ |
62 | temp = v->counter; |
63 | temp += i; |
64 | v->counter = temp; |
65 | raw_local_irq_restore(flags); |
66 | |
67 | return temp; |
68 | } |
69 | |
70 | /** |
71 | * atomic_sub_return - subtract integer from atomic variable |
72 | * @i: integer value to subtract |
73 | * @v: pointer of type atomic_t |
74 | * |
75 | * Atomically subtracts @i from @v and returns the result |
76 | */ |
77 | static inline int atomic_sub_return(int i, atomic_t *v) |
78 | { |
79 | unsigned long flags; |
80 | int temp; |
81 | |
82 | raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ |
83 | temp = v->counter; |
84 | temp -= i; |
85 | v->counter = temp; |
86 | raw_local_irq_restore(flags); |
87 | |
88 | return temp; |
89 | } |
90 | |
91 | static inline int atomic_add_negative(int i, atomic_t *v) |
92 | { |
93 | return atomic_add_return(i, v) < 0; |
94 | } |
95 | |
96 | static inline void atomic_add(int i, atomic_t *v) |
97 | { |
98 | atomic_add_return(i, v); |
99 | } |
100 | |
101 | static inline void atomic_sub(int i, atomic_t *v) |
102 | { |
103 | atomic_sub_return(i, v); |
104 | } |
105 | |
106 | static inline void atomic_inc(atomic_t *v) |
107 | { |
108 | atomic_add_return(1, v); |
109 | } |
110 | |
111 | static inline void atomic_dec(atomic_t *v) |
112 | { |
113 | atomic_sub_return(1, v); |
114 | } |
115 | |
116 | #define atomic_dec_return(v) atomic_sub_return(1, (v)) |
117 | #define atomic_inc_return(v) atomic_add_return(1, (v)) |
118 | |
119 | #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) |
120 | #define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0) |
121 | #define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0) |
122 | |
123 | #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) |
124 | #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) |
125 | |
126 | #define cmpxchg_local(ptr, o, n) \ |
127 | ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ |
128 | (unsigned long)(n), sizeof(*(ptr)))) |
129 | |
130 | #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) |
131 | |
132 | static inline int atomic_add_unless(atomic_t *v, int a, int u) |
133 | { |
134 | int c, old; |
135 | c = atomic_read(v); |
136 | while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) |
137 | c = old; |
138 | return c != u; |
139 | } |
140 | |
141 | #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) |
142 | |
143 | static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) |
144 | { |
145 | unsigned long flags; |
146 | |
147 | mask = ~mask; |
148 | raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ |
149 | *addr &= mask; |
150 | raw_local_irq_restore(flags); |
151 | } |
152 | |
153 | /* Assume that atomic operations are already serializing */ |
154 | #define smp_mb__before_atomic_dec() barrier() |
155 | #define smp_mb__after_atomic_dec() barrier() |
156 | #define smp_mb__before_atomic_inc() barrier() |
157 | #define smp_mb__after_atomic_inc() barrier() |
158 | |
159 | #include <asm-generic/atomic-long.h> |
160 | |
161 | #endif /* __KERNEL__ */ |
162 | #endif /* __ASM_GENERIC_ATOMIC_H */ |
163 |
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