| 1 | |
| 2 | * Generic C implementation of atomic counter operations. Usable on
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| 3 | * UP systems only. Do not include in machine independent code.
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| 4 | *
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| 5 | * Originally implemented for MN10300.
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| 6 | *
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| 7 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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| 8 | * Written by David Howells ([email protected])
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| 9 | *
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| 10 | * This program is free software; you can redistribute it and/or
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| 11 | * modify it under the terms of the GNU General Public Licence
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| 12 | * as published by the Free Software Foundation; either version
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| 13 | * 2 of the Licence, or (at your option) any later version.
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| 14 |
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| 15 | #ifndef __ASM_GENERIC_ATOMIC_H
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| 16 | #define __ASM_GENERIC_ATOMIC_H
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| 17 |
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| 18 | #include <asm/cmpxchg.h>
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| 19 | #include <asm/barrier.h>
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| 20 |
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| 21 | |
| 22 | * atomic_$op() - $op integer to atomic variable
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| 23 | * @i: integer value to $op
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| 24 | * @v: pointer to the atomic variable
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| 25 | *
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| 26 | * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use
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| 27 | * smp_mb__{before,after}_atomic().
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| 28 |
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| 29 |
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| 30 | |
| 31 | * atomic_$op_return() - $op interer to atomic variable and returns the result
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| 32 | * @i: integer value to $op
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| 33 | * @v: pointer to the atomic variable
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| 34 | *
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| 35 | * Atomically $ops @i to @v. Does imply a full memory barrier.
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| 36 |
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| 37 |
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| 38 | #ifdef CONFIG_SMP
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| 39 |
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| 40 |
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| 41 |
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| 42 | #define ATOMIC_OP(op, c_op) \
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| 43 | static inline void atomic_##op(int i, atomic_t *v) \
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| 44 | { \
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| 45 | int c, old; \
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| 46 | \
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| 47 | c = v->counter; \
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| 48 | while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
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| 49 | c = old; \
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| 50 | }
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| 51 |
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| 52 | #define ATOMIC_OP_RETURN(op, c_op) \
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| 53 | static inline int atomic_##op##_return(int i, atomic_t *v) \
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| 54 | { \
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| 55 | int c, old; \
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| 56 | \
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| 57 | c = v->counter; \
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| 58 | while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
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| 59 | c = old; \
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| 60 | \
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| 61 | return c c_op i; \
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| 62 | }
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| 63 |
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| 64 | #define ATOMIC_FETCH_OP(op, c_op) \
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| 65 | static inline int atomic_fetch_##op(int i, atomic_t *v) \
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| 66 | { \
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| 67 | int c, old; \
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| 68 | \
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| 69 | c = v->counter; \
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| 70 | while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
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| 71 | c = old; \
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| 72 | \
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| 73 | return c; \
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| 74 | }
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| 75 |
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| 76 | #else
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| 77 |
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| 78 | #include <linux/irqflags.h>
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| 79 |
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| 80 | #define ATOMIC_OP(op, c_op) \
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| 81 | static inline void atomic_##op(int i, atomic_t *v) \
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| 82 | { \
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| 83 | unsigned long flags; \
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| 84 | \
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| 85 | raw_local_irq_save(flags); \
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| 86 | v->counter = v->counter c_op i; \
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| 87 | raw_local_irq_restore(flags); \
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| 88 | }
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| 89 |
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| 90 | #define ATOMIC_OP_RETURN(op, c_op) \
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| 91 | static inline int atomic_##op##_return(int i, atomic_t *v) \
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| 92 | { \
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| 93 | unsigned long flags; \
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| 94 | int ret; \
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| 95 | \
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| 96 | raw_local_irq_save(flags); \
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| 97 | ret = (v->counter = v->counter c_op i); \
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| 98 | raw_local_irq_restore(flags); \
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| 99 | \
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| 100 | return ret; \
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| 101 | }
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| 102 |
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| 103 | #define ATOMIC_FETCH_OP(op, c_op) \
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| 104 | static inline int atomic_fetch_##op(int i, atomic_t *v) \
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| 105 | { \
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| 106 | unsigned long flags; \
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| 107 | int ret; \
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| 108 | \
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| 109 | raw_local_irq_save(flags); \
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| 110 | ret = v->counter; \
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| 111 | v->counter = v->counter c_op i; \
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| 112 | raw_local_irq_restore(flags); \
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| 113 | \
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| 114 | return ret; \
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| 115 | }
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| 116 |
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| 117 | #endif
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| 118 |
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| 119 | #ifndef atomic_add_return
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| 120 | ATOMIC_OP_RETURN(add, +)
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| 121 | #endif
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| 122 |
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| 123 | #ifndef atomic_sub_return
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| 124 | ATOMIC_OP_RETURN(sub, -)
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| 125 | #endif
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| 126 |
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| 127 | #ifndef atomic_fetch_add
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| 128 | ATOMIC_FETCH_OP(add, +)
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| 129 | #endif
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| 130 |
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| 131 | #ifndef atomic_fetch_sub
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| 132 | ATOMIC_FETCH_OP(sub, -)
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| 133 | #endif
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| 134 |
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| 135 | #ifndef atomic_fetch_and
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| 136 | ATOMIC_FETCH_OP(and, &)
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| 137 | #endif
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| 138 |
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| 139 | #ifndef atomic_fetch_or
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| 140 | ATOMIC_FETCH_OP(or, |)
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| 141 | #endif
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| 142 |
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| 143 | #ifndef atomic_fetch_xor
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| 144 | ATOMIC_FETCH_OP(xor, ^)
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| 145 | #endif
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| 146 |
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| 147 | #ifndef atomic_and
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| 148 | ATOMIC_OP(and, &)
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| 149 | #endif
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| 150 |
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| 151 | #ifndef atomic_or
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| 152 | ATOMIC_OP(or, |)
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| 153 | #endif
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| 154 |
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| 155 | #ifndef atomic_xor
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| 156 | ATOMIC_OP(xor, ^)
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| 157 | #endif
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| 158 |
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| 159 | #undef ATOMIC_FETCH_OP
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| 160 | #undef ATOMIC_OP_RETURN
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| 161 | #undef ATOMIC_OP
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| 162 |
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| 163 | |
| 164 | * Atomic operations that C can't guarantee us. Useful for
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| 165 | * resource counting etc..
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| 166 |
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| 167 |
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| 168 | #define ATOMIC_INIT(i) { (i) }
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| 169 |
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| 170 | |
| 171 | * atomic_read - read atomic variable
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| 172 | * @v: pointer of type atomic_t
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| 173 | *
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| 174 | * Atomically reads the value of @v.
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| 175 |
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| 176 | #ifndef atomic_read
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| 177 | #define atomic_read(v) READ_ONCE((v)->counter)
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| 178 | #endif
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| 179 |
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| 180 | |
| 181 | * atomic_set - set atomic variable
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| 182 | * @v: pointer of type atomic_t
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| 183 | * @i: required value
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| 184 | *
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| 185 | * Atomically sets the value of @v to @i.
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| 186 |
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| 187 | #define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
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| 188 |
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| 189 | #include <linux/irqflags.h>
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| 190 |
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| 191 | static inline int atomic_add_negative(int i, atomic_t *v)
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| 192 | {
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| 193 | return atomic_add_return(i, v) < 0;
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| 194 | }
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| 195 |
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| 196 | static inline void atomic_add(int i, atomic_t *v)
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| 197 | {
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| 198 | atomic_add_return(i, v);
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| 199 | }
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| 200 |
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| 201 | static inline void atomic_sub(int i, atomic_t *v)
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| 202 | {
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| 203 | atomic_sub_return(i, v);
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| 204 | }
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| 205 |
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| 206 | static inline void atomic_inc(atomic_t *v)
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| 207 | {
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| 208 | atomic_add_return(1, v);
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| 209 | }
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| 210 |
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| 211 | static inline void atomic_dec(atomic_t *v)
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| 212 | {
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| 213 | atomic_sub_return(1, v);
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| 214 | }
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| 215 |
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| 216 | #define atomic_dec_return(v) atomic_sub_return(1, (v))
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| 217 | #define atomic_inc_return(v) atomic_add_return(1, (v))
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| 218 |
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| 219 | #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
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| 220 | #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
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| 221 | #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
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| 222 |
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| 223 | #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
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| 224 | #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
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| 225 |
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| 226 | #ifndef __atomic_add_unless
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| 227 | static inline int __atomic_add_unless(atomic_t *v, int a, int u)
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| 228 | {
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| 229 | int c, old;
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| 230 | c = atomic_read(v);
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| 231 | while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
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| 232 | c = old;
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| 233 | return c;
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| 234 | }
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| 235 | #endif
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| 236 |
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| 237 | #endif
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