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#ifndef atomic_inc_not_zero
28#define atomic_inc_not_zero(v)		atomic_add_unless((v), 1, 0)
29#endif
30
31/**
32 * 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
63#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
89/*
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
114#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
127#include <asm-generic/atomic-long.h>
128#ifdef CONFIG_GENERIC_ATOMIC64
129#include <asm-generic/atomic64.h>
130#endif
131#endif /* _LINUX_ATOMIC_H */
132