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