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. */
22 typedef 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
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.