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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 | */ |
15 | static 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 |
44 | static 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 |
64 | static 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 |
77 | static 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 |
97 | static 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 |
115 | static 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 |
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