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Arun Sharmaacac43e2011-07-26 16:09:08 -07001/* Atomic operations usable in machine independent code */
Eric Dumazet3f9d35b2010-11-11 14:05:08 -08002#ifndef _LINUX_ATOMIC_H
3#define _LINUX_ATOMIC_H
4#include <asm/atomic.h>
5
6/**
Arun Sharmaf24219b2011-07-26 16:09:07 -07007 * 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/**
Arun Sharma600634972011-07-26 16:09:06 -070021 * 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 */
Anton Blanchardb1ada602012-02-29 21:09:53 +000027#ifndef atomic_inc_not_zero
Arun Sharma600634972011-07-26 16:09:06 -070028#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
Anton Blanchardb1ada602012-02-29 21:09:53 +000029#endif
Arun Sharma600634972011-07-26 16:09:06 -070030
31/**
Eric Dumazet3f9d35b2010-11-11 14:05:08 -080032 * atomic_inc_not_zero_hint - increment if not null
33 * @v: pointer of type atomic_t
34 * @hint: probable value of the atomic before the increment
35 *
36 * This version of atomic_inc_not_zero() gives a hint of probable
37 * value of the atomic. This helps processor to not read the memory
38 * before doing the atomic read/modify/write cycle, lowering
39 * number of bus transactions on some arches.
40 *
41 * Returns: 0 if increment was not done, 1 otherwise.
42 */
43#ifndef atomic_inc_not_zero_hint
44static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
45{
46 int val, c = hint;
47
48 /* sanity test, should be removed by compiler if hint is a constant */
49 if (!hint)
50 return atomic_inc_not_zero(v);
51
52 do {
53 val = atomic_cmpxchg(v, c, c + 1);
54 if (val == c)
55 return 1;
56 c = val;
57 } while (c);
58
59 return 0;
60}
61#endif
62
Al Viro07b8ce12011-06-20 10:52:57 -040063#ifndef atomic_inc_unless_negative
64static inline int atomic_inc_unless_negative(atomic_t *p)
65{
66 int v, v1;
67 for (v = 0; v >= 0; v = v1) {
68 v1 = atomic_cmpxchg(p, v, v + 1);
69 if (likely(v1 == v))
70 return 1;
71 }
72 return 0;
73}
74#endif
75
76#ifndef atomic_dec_unless_positive
77static inline int atomic_dec_unless_positive(atomic_t *p)
78{
79 int v, v1;
80 for (v = 0; v <= 0; v = v1) {
81 v1 = atomic_cmpxchg(p, v, v - 1);
82 if (likely(v1 == v))
83 return 1;
84 }
85 return 0;
86}
87#endif
88
Shaohua Lie79bee22012-10-08 16:32:18 -070089/*
90 * atomic_dec_if_positive - decrement by 1 if old value positive
91 * @v: pointer of type atomic_t
92 *
93 * The function returns the old value of *v minus 1, even if
94 * the atomic variable, v, was not decremented.
95 */
96#ifndef atomic_dec_if_positive
97static inline int atomic_dec_if_positive(atomic_t *v)
98{
99 int c, old, dec;
100 c = atomic_read(v);
101 for (;;) {
102 dec = c - 1;
103 if (unlikely(dec < 0))
104 break;
105 old = atomic_cmpxchg((v), c, dec);
106 if (likely(old == c))
107 break;
108 c = old;
109 }
110 return dec;
111}
112#endif
113
Paul E. McKenney55c29452011-05-11 05:33:33 -0700114#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
115static inline void atomic_or(int i, atomic_t *v)
116{
117 int old;
118 int new;
119
120 do {
121 old = atomic_read(v);
122 new = old | i;
123 } while (atomic_cmpxchg(v, old, new) != old);
124}
125#endif /* #ifndef CONFIG_ARCH_HAS_ATOMIC_OR */
126
Arun Sharma78477772011-07-26 16:09:08 -0700127#include <asm-generic/atomic-long.h>
128#ifdef CONFIG_GENERIC_ATOMIC64
129#include <asm-generic/atomic64.h>
130#endif
Eric Dumazet3f9d35b2010-11-11 14:05:08 -0800131#endif /* _LINUX_ATOMIC_H */