Root/include/asm-generic/local.h

1#ifndef _ASM_GENERIC_LOCAL_H
2#define _ASM_GENERIC_LOCAL_H
3
4#include <linux/percpu.h>
5#include <asm/atomic.h>
6#include <asm/types.h>
7
8/*
9 * A signed long type for operations which are atomic for a single CPU.
10 * Usually used in combination with per-cpu variables.
11 *
12 * This is the default implementation, which uses atomic_long_t. Which is
13 * rather pointless. The whole point behind local_t is that some processors
14 * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
15 * running on this CPU. local_t allows exploitation of such capabilities.
16 */
17
18/* Implement in terms of atomics. */
19
20/* Don't use typedef: don't want them to be mixed with atomic_t's. */
21typedef struct
22{
23    atomic_long_t a;
24} local_t;
25
26#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
27
28#define local_read(l) atomic_long_read(&(l)->a)
29#define local_set(l,i) atomic_long_set((&(l)->a),(i))
30#define local_inc(l) atomic_long_inc(&(l)->a)
31#define local_dec(l) atomic_long_dec(&(l)->a)
32#define local_add(i,l) atomic_long_add((i),(&(l)->a))
33#define local_sub(i,l) atomic_long_sub((i),(&(l)->a))
34
35#define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a))
36#define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a)
37#define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a)
38#define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a))
39#define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
40#define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a))
41#define local_inc_return(l) atomic_long_inc_return(&(l)->a)
42
43#define local_cmpxchg(l, o, n) atomic_long_cmpxchg((&(l)->a), (o), (n))
44#define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
45#define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u))
46#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
47
48/* Non-atomic variants, ie. preemption disabled and won't be touched
49 * in interrupt, etc. Some archs can optimize this case well. */
50#define __local_inc(l) local_set((l), local_read(l) + 1)
51#define __local_dec(l) local_set((l), local_read(l) - 1)
52#define __local_add(i,l) local_set((l), local_read(l) + (i))
53#define __local_sub(i,l) local_set((l), local_read(l) - (i))
54
55#endif /* _ASM_GENERIC_LOCAL_H */
56

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