blob: fc218444e3153cc29c8610388163a806f8cc5f4f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _ASM_GENERIC_LOCAL_H
2#define _ASM_GENERIC_LOCAL_H
3
Linus Torvalds1da177e2005-04-16 15:20:36 -07004#include <linux/percpu.h>
Kyle McMartinf5f53702006-03-28 01:56:11 -08005#include <asm/atomic.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07006#include <asm/types.h>
7
Andrew Morton2cf8d822006-03-31 02:30:49 -08008/*
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 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
Linus Torvalds1da177e2005-04-16 15:20:36 -070018/* 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{
Kyle McMartinf5f53702006-03-28 01:56:11 -080023 atomic_long_t a;
Linus Torvalds1da177e2005-04-16 15:20:36 -070024} local_t;
25
Kyle McMartinf5f53702006-03-28 01:56:11 -080026#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
Andrew Morton2cf8d822006-03-31 02:30:49 -080028#define local_read(l) atomic_long_read(&(l)->a)
Kyle McMartinf5f53702006-03-28 01:56:11 -080029#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))
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Mathieu Desnoyers5e97b932007-05-08 00:34:40 -070035#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))
Roel Kluinbac9caf2009-05-17 18:18:58 -070045#define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u))
Mathieu Desnoyers5e97b932007-05-08 00:34:40 -070046#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
47
Linus Torvalds1da177e2005-04-16 15:20:36 -070048/* 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070055/* Use these for per-cpu local_t variables: on some archs they are
56 * much more efficient than these naive implementations. Note they take
57 * a variable (eg. mystruct.foo), not an address.
58 */
Mathieu Desnoyers5e97b932007-05-08 00:34:40 -070059#define cpu_local_read(l) local_read(&__get_cpu_var(l))
60#define cpu_local_set(l, i) local_set(&__get_cpu_var(l), (i))
61#define cpu_local_inc(l) local_inc(&__get_cpu_var(l))
62#define cpu_local_dec(l) local_dec(&__get_cpu_var(l))
63#define cpu_local_add(i, l) local_add((i), &__get_cpu_var(l))
64#define cpu_local_sub(i, l) local_sub((i), &__get_cpu_var(l))
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
66/* Non-atomic increments, ie. preemption disabled and won't be touched
67 * in interrupt, etc. Some archs can optimize this case well.
68 */
Mathieu Desnoyers5e97b932007-05-08 00:34:40 -070069#define __cpu_local_inc(l) __local_inc(&__get_cpu_var(l))
70#define __cpu_local_dec(l) __local_dec(&__get_cpu_var(l))
71#define __cpu_local_add(i, l) __local_add((i), &__get_cpu_var(l))
72#define __cpu_local_sub(i, l) __local_sub((i), &__get_cpu_var(l))
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
74#endif /* _ASM_GENERIC_LOCAL_H */