1#ifndef _ASM_GENERIC_LOCAL_H
2#define _ASM_GENERIC_LOCAL_H
3
4#include <linux/percpu.h>
5#include <linux/hardirq.h>
6#include <asm/atomic.h>
7#include <asm/types.h>
8
9/*
10 * A signed long type for operations which are atomic for a single CPU.
11 * Usually used in combination with per-cpu variables.
12 *
13 * This is the default implementation, which uses atomic_long_t.  Which is
14 * rather pointless.  The whole point behind local_t is that some processors
15 * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
16 * running on this CPU.  local_t allows exploitation of such capabilities.
17 */
18
19/* Implement in terms of atomics. */
20
21/* Don't use typedef: don't want them to be mixed with atomic_t's. */
22typedef struct
23{
24	atomic_long_t a;
25} local_t;
26
27#define LOCAL_INIT(i)	{ ATOMIC_LONG_INIT(i) }
28
29#define local_read(l)	atomic_long_read(&(l)->a)
30#define local_set(l,i)	atomic_long_set((&(l)->a),(i))
31#define local_inc(l)	atomic_long_inc(&(l)->a)
32#define local_dec(l)	atomic_long_dec(&(l)->a)
33#define local_add(i,l)	atomic_long_add((i),(&(l)->a))
34#define local_sub(i,l)	atomic_long_sub((i),(&(l)->a))
35
36/* Non-atomic variants, ie. preemption disabled and won't be touched
37 * in interrupt, etc.  Some archs can optimize this case well. */
38#define __local_inc(l)		local_set((l), local_read(l) + 1)
39#define __local_dec(l)		local_set((l), local_read(l) - 1)
40#define __local_add(i,l)	local_set((l), local_read(l) + (i))
41#define __local_sub(i,l)	local_set((l), local_read(l) - (i))
42
43/* Use these for per-cpu local_t variables: on some archs they are
44 * much more efficient than these naive implementations.  Note they take
45 * a variable (eg. mystruct.foo), not an address.
46 */
47#define cpu_local_read(v)	local_read(&__get_cpu_var(v))
48#define cpu_local_set(v, i)	local_set(&__get_cpu_var(v), (i))
49#define cpu_local_inc(v)	local_inc(&__get_cpu_var(v))
50#define cpu_local_dec(v)	local_dec(&__get_cpu_var(v))
51#define cpu_local_add(i, v)	local_add((i), &__get_cpu_var(v))
52#define cpu_local_sub(i, v)	local_sub((i), &__get_cpu_var(v))
53
54/* Non-atomic increments, ie. preemption disabled and won't be touched
55 * in interrupt, etc.  Some archs can optimize this case well.
56 */
57#define __cpu_local_inc(v)	__local_inc(&__get_cpu_var(v))
58#define __cpu_local_dec(v)	__local_dec(&__get_cpu_var(v))
59#define __cpu_local_add(i, v)	__local_add((i), &__get_cpu_var(v))
60#define __cpu_local_sub(i, v)	__local_sub((i), &__get_cpu_var(v))
61
62#endif /* _ASM_GENERIC_LOCAL_H */
63