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3f7e212d AB |
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. Note that the guaranteed | |
34 | * useful range of an atomic_t is only 24 bits. | |
35 | */ | |
36 | #define atomic_read(v) ((v)->counter) | |
37 | ||
38 | /** | |
39 | * atomic_set - set atomic variable | |
40 | * @v: pointer of type atomic_t | |
41 | * @i: required value | |
42 | * | |
43 | * Atomically sets the value of @v to @i. Note that the guaranteed | |
44 | * useful range of an atomic_t is only 24 bits. | |
45 | */ | |
46 | #define atomic_set(v, i) (((v)->counter) = (i)) | |
47 | ||
48 | #include <asm/system.h> | |
49 | ||
50 | /** | |
51 | * atomic_add_return - add integer to atomic variable | |
52 | * @i: integer value to add | |
53 | * @v: pointer of type atomic_t | |
54 | * | |
55 | * Atomically adds @i to @v and returns the result | |
56 | * Note that the guaranteed useful range of an atomic_t is only 24 bits. | |
57 | */ | |
58 | static inline int atomic_add_return(int i, atomic_t *v) | |
59 | { | |
60 | unsigned long flags; | |
61 | int temp; | |
62 | ||
63 | local_irq_save(flags); | |
64 | temp = v->counter; | |
65 | temp += i; | |
66 | v->counter = temp; | |
67 | local_irq_restore(flags); | |
68 | ||
69 | return temp; | |
70 | } | |
71 | ||
72 | /** | |
73 | * atomic_sub_return - subtract integer from atomic variable | |
74 | * @i: integer value to subtract | |
75 | * @v: pointer of type atomic_t | |
76 | * | |
77 | * Atomically subtracts @i from @v and returns the result | |
78 | * Note that the guaranteed useful range of an atomic_t is only 24 bits. | |
79 | */ | |
80 | static inline int atomic_sub_return(int i, atomic_t *v) | |
81 | { | |
82 | unsigned long flags; | |
83 | int temp; | |
84 | ||
85 | local_irq_save(flags); | |
86 | temp = v->counter; | |
87 | temp -= i; | |
88 | v->counter = temp; | |
89 | local_irq_restore(flags); | |
90 | ||
91 | return temp; | |
92 | } | |
93 | ||
94 | static inline int atomic_add_negative(int i, atomic_t *v) | |
95 | { | |
96 | return atomic_add_return(i, v) < 0; | |
97 | } | |
98 | ||
99 | static inline void atomic_add(int i, atomic_t *v) | |
100 | { | |
101 | atomic_add_return(i, v); | |
102 | } | |
103 | ||
104 | static inline void atomic_sub(int i, atomic_t *v) | |
105 | { | |
106 | atomic_sub_return(i, v); | |
107 | } | |
108 | ||
109 | static inline void atomic_inc(atomic_t *v) | |
110 | { | |
111 | atomic_add_return(1, v); | |
112 | } | |
113 | ||
114 | static inline void atomic_dec(atomic_t *v) | |
115 | { | |
116 | atomic_sub_return(1, v); | |
117 | } | |
118 | ||
119 | #define atomic_dec_return(v) atomic_sub_return(1, (v)) | |
120 | #define atomic_inc_return(v) atomic_add_return(1, (v)) | |
121 | ||
122 | #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) | |
123 | #define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0) | |
124 | #define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0) | |
125 | ||
126 | #define atomic_add_unless(v, a, u) \ | |
127 | ({ \ | |
128 | int c, old; \ | |
129 | c = atomic_read(v); \ | |
130 | while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ | |
131 | c = old; \ | |
132 | c != (u); \ | |
133 | }) | |
134 | ||
135 | #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) | |
136 | ||
137 | static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) | |
138 | { | |
139 | unsigned long flags; | |
140 | ||
141 | mask = ~mask; | |
142 | local_irq_save(flags); | |
143 | *addr &= mask; | |
144 | local_irq_restore(flags); | |
145 | } | |
146 | ||
147 | #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) | |
148 | #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) | |
149 | ||
150 | #define cmpxchg_local(ptr, o, n) \ | |
151 | ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ | |
152 | (unsigned long)(n), sizeof(*(ptr)))) | |
153 | ||
154 | #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) | |
155 | ||
156 | /* Assume that atomic operations are already serializing */ | |
157 | #define smp_mb__before_atomic_dec() barrier() | |
158 | #define smp_mb__after_atomic_dec() barrier() | |
159 | #define smp_mb__before_atomic_inc() barrier() | |
160 | #define smp_mb__after_atomic_inc() barrier() | |
161 | ||
162 | #include <asm-generic/atomic-long.h> | |
163 | ||
164 | #endif /* __KERNEL__ */ | |
165 | #endif /* __ASM_GENERIC_ATOMIC_H */ |