1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_GENERIC_LOCAL_H
3#define _ASM_GENERIC_LOCAL_H
4
5#include <linux/percpu.h>
6#include <linux/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#define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a))
37#define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a)
38#define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a)
39#define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a))
40#define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
41#define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a))
42#define local_inc_return(l) atomic_long_inc_return(&(l)->a)
43
44#define local_cmpxchg(l, o, n) atomic_long_cmpxchg((&(l)->a), (o), (n))
45#define local_try_cmpxchg(l, po, n) atomic_long_try_cmpxchg((&(l)->a), (po), (n))
46#define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
47#define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u))
48#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
49
50/* Non-atomic variants, ie. preemption disabled and won't be touched
51 * in interrupt, etc.  Some archs can optimize this case well. */
52#define __local_inc(l)		local_set((l), local_read(l) + 1)
53#define __local_dec(l)		local_set((l), local_read(l) - 1)
54#define __local_add(i,l)	local_set((l), local_read(l) + (i))
55#define __local_sub(i,l)	local_set((l), local_read(l) - (i))
56
57#endif /* _ASM_GENERIC_LOCAL_H */
58