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1/* Atomic operations usable in machine independent code */
2#ifndef _LINUX_ATOMIC_H
3#define _LINUX_ATOMIC_H
4#include <asm/atomic.h>
5
6/*
7 * Provide __deprecated wrappers for the new interface, avoid flag day changes.
8 * We need the ugly external functions to break header recursion hell.
9 */
10#ifndef smp_mb__before_atomic_inc
11static inline void __deprecated smp_mb__before_atomic_inc(void)
12{
13 extern void __smp_mb__before_atomic(void);
14 __smp_mb__before_atomic();
15}
16#endif
17
18#ifndef smp_mb__after_atomic_inc
19static inline void __deprecated smp_mb__after_atomic_inc(void)
20{
21 extern void __smp_mb__after_atomic(void);
22 __smp_mb__after_atomic();
23}
24#endif
25
26#ifndef smp_mb__before_atomic_dec
27static inline void __deprecated smp_mb__before_atomic_dec(void)
28{
29 extern void __smp_mb__before_atomic(void);
30 __smp_mb__before_atomic();
31}
32#endif
33
34#ifndef smp_mb__after_atomic_dec
35static inline void __deprecated smp_mb__after_atomic_dec(void)
36{
37 extern void __smp_mb__after_atomic(void);
38 __smp_mb__after_atomic();
39}
40#endif
41
42/**
43 * atomic_add_unless - add unless the number is already a given value
44 * @v: pointer of type atomic_t
45 * @a: the amount to add to v...
46 * @u: ...unless v is equal to u.
47 *
48 * Atomically adds @a to @v, so long as @v was not already @u.
49 * Returns non-zero if @v was not @u, and zero otherwise.
50 */
51static inline int atomic_add_unless(atomic_t *v, int a, int u)
52{
53 return __atomic_add_unless(v, a, u) != u;
54}
55
56/**
57 * atomic_inc_not_zero - increment unless the number is zero
58 * @v: pointer of type atomic_t
59 *
60 * Atomically increments @v by 1, so long as @v is non-zero.
61 * Returns non-zero if @v was non-zero, and zero otherwise.
62 */
63#ifndef atomic_inc_not_zero
64#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
65#endif
66
67/**
68 * atomic_inc_not_zero_hint - increment if not null
69 * @v: pointer of type atomic_t
70 * @hint: probable value of the atomic before the increment
71 *
72 * This version of atomic_inc_not_zero() gives a hint of probable
73 * value of the atomic. This helps processor to not read the memory
74 * before doing the atomic read/modify/write cycle, lowering
75 * number of bus transactions on some arches.
76 *
77 * Returns: 0 if increment was not done, 1 otherwise.
78 */
79#ifndef atomic_inc_not_zero_hint
80static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
81{
82 int val, c = hint;
83
84 /* sanity test, should be removed by compiler if hint is a constant */
85 if (!hint)
86 return atomic_inc_not_zero(v);
87
88 do {
89 val = atomic_cmpxchg(v, c, c + 1);
90 if (val == c)
91 return 1;
92 c = val;
93 } while (c);
94
95 return 0;
96}
97#endif
98
99#ifndef atomic_inc_unless_negative
100static inline int atomic_inc_unless_negative(atomic_t *p)
101{
102 int v, v1;
103 for (v = 0; v >= 0; v = v1) {
104 v1 = atomic_cmpxchg(p, v, v + 1);
105 if (likely(v1 == v))
106 return 1;
107 }
108 return 0;
109}
110#endif
111
112#ifndef atomic_dec_unless_positive
113static inline int atomic_dec_unless_positive(atomic_t *p)
114{
115 int v, v1;
116 for (v = 0; v <= 0; v = v1) {
117 v1 = atomic_cmpxchg(p, v, v - 1);
118 if (likely(v1 == v))
119 return 1;
120 }
121 return 0;
122}
123#endif
124
125/*
126 * atomic_dec_if_positive - decrement by 1 if old value positive
127 * @v: pointer of type atomic_t
128 *
129 * The function returns the old value of *v minus 1, even if
130 * the atomic variable, v, was not decremented.
131 */
132#ifndef atomic_dec_if_positive
133static inline int atomic_dec_if_positive(atomic_t *v)
134{
135 int c, old, dec;
136 c = atomic_read(v);
137 for (;;) {
138 dec = c - 1;
139 if (unlikely(dec < 0))
140 break;
141 old = atomic_cmpxchg((v), c, dec);
142 if (likely(old == c))
143 break;
144 c = old;
145 }
146 return dec;
147}
148#endif
149
150#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
151static inline void atomic_or(int i, atomic_t *v)
152{
153 int old;
154 int new;
155
156 do {
157 old = atomic_read(v);
158 new = old | i;
159 } while (atomic_cmpxchg(v, old, new) != old);
160}
161#endif /* #ifndef CONFIG_ARCH_HAS_ATOMIC_OR */
162
163#include <asm-generic/atomic-long.h>
164#ifdef CONFIG_GENERIC_ATOMIC64
165#include <asm-generic/atomic64.h>
166#endif
167#endif /* _LINUX_ATOMIC_H */