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| Rev | Author | Line No. | Line |
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| 5270 | serge | 1 | /* Atomic operations usable in machine independent code */ |
| 2 | #ifndef _LINUX_ATOMIC_H |
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| 3 | #define _LINUX_ATOMIC_H |
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| 4 | #include |
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| 5 | |||
| 6 | /** |
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| 7 | * atomic_add_unless - add unless the number is already a given value |
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| 8 | * @v: pointer of type atomic_t |
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| 9 | * @a: the amount to add to v... |
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| 10 | * @u: ...unless v is equal to u. |
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| 11 | * |
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| 12 | * Atomically adds @a to @v, so long as @v was not already @u. |
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| 13 | * Returns non-zero if @v was not @u, and zero otherwise. |
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| 14 | */ |
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| 15 | static inline int atomic_add_unless(atomic_t *v, int a, int u) |
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| 16 | { |
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| 17 | return __atomic_add_unless(v, a, u) != u; |
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| 18 | } |
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| 19 | |||
| 20 | /** |
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| 21 | * atomic_inc_not_zero - increment unless the number is zero |
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| 22 | * @v: pointer of type atomic_t |
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| 23 | * |
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| 24 | * Atomically increments @v by 1, so long as @v is non-zero. |
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| 25 | * Returns non-zero if @v was non-zero, and zero otherwise. |
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| 26 | */ |
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| 27 | #ifndef atomic_inc_not_zero |
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| 28 | #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) |
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| 29 | #endif |
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| 30 | |||
| 31 | /** |
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| 32 | * atomic_inc_not_zero_hint - increment if not null |
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| 33 | * @v: pointer of type atomic_t |
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| 34 | * @hint: probable value of the atomic before the increment |
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| 35 | * |
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| 36 | * This version of atomic_inc_not_zero() gives a hint of probable |
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| 37 | * value of the atomic. This helps processor to not read the memory |
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| 38 | * before doing the atomic read/modify/write cycle, lowering |
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| 39 | * number of bus transactions on some arches. |
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| 40 | * |
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| 41 | * Returns: 0 if increment was not done, 1 otherwise. |
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| 42 | */ |
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| 43 | #ifndef atomic_inc_not_zero_hint |
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| 44 | static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint) |
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| 45 | { |
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| 46 | int val, c = hint; |
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| 47 | |||
| 48 | /* sanity test, should be removed by compiler if hint is a constant */ |
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| 49 | if (!hint) |
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| 50 | return atomic_inc_not_zero(v); |
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| 51 | |||
| 52 | do { |
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| 53 | val = atomic_cmpxchg(v, c, c + 1); |
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| 54 | if (val == c) |
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| 55 | return 1; |
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| 56 | c = val; |
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| 57 | } while (c); |
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| 58 | |||
| 59 | return 0; |
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| 60 | } |
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| 61 | #endif |
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| 62 | |||
| 63 | #ifndef atomic_inc_unless_negative |
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| 64 | static inline int atomic_inc_unless_negative(atomic_t *p) |
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| 65 | { |
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| 66 | int v, v1; |
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| 67 | for (v = 0; v >= 0; v = v1) { |
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| 68 | v1 = atomic_cmpxchg(p, v, v + 1); |
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| 69 | if (likely(v1 == v)) |
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| 70 | return 1; |
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| 71 | } |
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| 72 | return 0; |
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| 73 | } |
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| 74 | #endif |
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| 75 | |||
| 76 | #ifndef atomic_dec_unless_positive |
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| 77 | static inline int atomic_dec_unless_positive(atomic_t *p) |
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| 78 | { |
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| 79 | int v, v1; |
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| 80 | for (v = 0; v <= 0; v = v1) { |
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| 81 | v1 = atomic_cmpxchg(p, v, v - 1); |
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| 82 | if (likely(v1 == v)) |
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| 83 | return 1; |
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| 84 | } |
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| 85 | return 0; |
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| 86 | } |
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| 87 | #endif |
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| 88 | |||
| 89 | /* |
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| 90 | * atomic_dec_if_positive - decrement by 1 if old value positive |
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| 91 | * @v: pointer of type atomic_t |
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| 92 | * |
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| 93 | * The function returns the old value of *v minus 1, even if |
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| 94 | * the atomic variable, v, was not decremented. |
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| 95 | */ |
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| 96 | #ifndef atomic_dec_if_positive |
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| 97 | static inline int atomic_dec_if_positive(atomic_t *v) |
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| 98 | { |
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| 99 | int c, old, dec; |
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| 100 | c = atomic_read(v); |
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| 101 | for (;;) { |
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| 102 | dec = c - 1; |
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| 103 | if (unlikely(dec < 0)) |
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| 104 | break; |
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| 105 | old = atomic_cmpxchg((v), c, dec); |
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| 106 | if (likely(old == c)) |
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| 107 | break; |
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| 108 | c = old; |
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| 109 | } |
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| 110 | return dec; |
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| 111 | } |
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| 112 | #endif |
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| 113 | |||
| 114 | #ifndef CONFIG_ARCH_HAS_ATOMIC_OR |
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| 115 | static inline void atomic_or(int i, atomic_t *v) |
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| 116 | { |
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| 117 | int old; |
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| 118 | int new; |
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| 119 | |||
| 120 | do { |
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| 121 | old = atomic_read(v); |
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| 122 | new = old | i; |
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| 123 | } while (atomic_cmpxchg(v, old, new) != old); |
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| 124 | } |
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| 125 | #endif /* #ifndef CONFIG_ARCH_HAS_ATOMIC_OR */ |
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| 126 | |||
| 127 | #include |
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| 128 | #ifdef CONFIG_GENERIC_ATOMIC64 |
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| 129 | #include |
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| 130 | #endif |
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| 131 | #endif /* _LINUX_ATOMIC_H */ |