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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 * atomic_add_unless - add unless the number is already a given value
8 * @v: pointer of type atomic_t
9 * @a: the amount to add to v...
10 * @u: ...unless v is equal to u.
11 *
12 * Atomically adds @a to @v, so long as @v was not already @u.
13 * Returns non-zero if @v was not @u, and zero otherwise.
14 */
15static inline int atomic_add_unless(atomic_t *v, int a, int u)
16{
17 return __atomic_add_unless(v, a, u) != u;
18}
19
20/**
21 * atomic_inc_not_zero - increment unless the number is zero
22 * @v: pointer of type atomic_t
23 *
24 * Atomically increments @v by 1, so long as @v is non-zero.
25 * Returns non-zero if @v was non-zero, and zero otherwise.
26 */
27#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
28
29/**
30 * atomic_inc_not_zero_hint - increment if not null
31 * @v: pointer of type atomic_t
32 * @hint: probable value of the atomic before the increment
33 *
34 * This version of atomic_inc_not_zero() gives a hint of probable
35 * value of the atomic. This helps processor to not read the memory
36 * before doing the atomic read/modify/write cycle, lowering
37 * number of bus transactions on some arches.
38 *
39 * Returns: 0 if increment was not done, 1 otherwise.
40 */
41#ifndef atomic_inc_not_zero_hint
42static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
43{
44 int val, c = hint;
45
46 /* sanity test, should be removed by compiler if hint is a constant */
47 if (!hint)
48 return atomic_inc_not_zero(v);
49
50 do {
51 val = atomic_cmpxchg(v, c, c + 1);
52 if (val == c)
53 return 1;
54 c = val;
55 } while (c);
56
57 return 0;
58}
59#endif
60
61#ifndef atomic_inc_unless_negative
62static inline int atomic_inc_unless_negative(atomic_t *p)
63{
64 int v, v1;
65 for (v = 0; v >= 0; v = v1) {
66 v1 = atomic_cmpxchg(p, v, v + 1);
67 if (likely(v1 == v))
68 return 1;
69 }
70 return 0;
71}
72#endif
73
74#ifndef atomic_dec_unless_positive
75static inline int atomic_dec_unless_positive(atomic_t *p)
76{
77 int v, v1;
78 for (v = 0; v <= 0; v = v1) {
79 v1 = atomic_cmpxchg(p, v, v - 1);
80 if (likely(v1 == v))
81 return 1;
82 }
83 return 0;
84}
85#endif
86
87#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
88static inline void atomic_or(int i, atomic_t *v)
89{
90 int old;
91 int new;
92
93 do {
94 old = atomic_read(v);
95 new = old | i;
96 } while (atomic_cmpxchg(v, old, new) != old);
97}
98#endif /* #ifndef CONFIG_ARCH_HAS_ATOMIC_OR */
99
100#include <asm-generic/atomic-long.h>
101#ifdef CONFIG_GENERIC_ATOMIC64
102#include <asm-generic/atomic64.h>
103#endif
104#endif /* _LINUX_ATOMIC_H */