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. */
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_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
46 #define local_add_unless(l, a, u) atomic_long_add_unless((&(l)->a), (a), (u))
47 #define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
48
49 /* Non-atomic variants, ie. preemption disabled and won't be touched
50 * in interrupt, etc. Some archs can optimize this case well. */
51 #define __local_inc(l) local_set((l), local_read(l) + 1)
52 #define __local_dec(l) local_set((l), local_read(l) - 1)
53 #define __local_add(i,l) local_set((l), local_read(l) + (i))
54 #define __local_sub(i,l) local_set((l), local_read(l) - (i))
55
56 /* Use these for per-cpu local_t variables: on some archs they are
57 * much more efficient than these naive implementations. Note they take
58 * a variable (eg. mystruct.foo), not an address.
59 */
60 #define cpu_local_read(l) local_read(&__get_cpu_var(l))
61 #define cpu_local_set(l, i) local_set(&__get_cpu_var(l), (i))
62 #define cpu_local_inc(l) local_inc(&__get_cpu_var(l))
63 #define cpu_local_dec(l) local_dec(&__get_cpu_var(l))
64 #define cpu_local_add(i, l) local_add((i), &__get_cpu_var(l))
65 #define cpu_local_sub(i, l) local_sub((i), &__get_cpu_var(l))
66
67 /* Non-atomic increments, ie. preemption disabled and won't be touched
68 * in interrupt, etc. Some archs can optimize this case well.
69 */
70 #define __cpu_local_inc(l) __local_inc(&__get_cpu_var(l))
71 #define __cpu_local_dec(l) __local_dec(&__get_cpu_var(l))
72 #define __cpu_local_add(i, l) __local_add((i), &__get_cpu_var(l))
73 #define __cpu_local_sub(i, l) __local_sub((i), &__get_cpu_var(l))
74
75 #endif /* _ASM_GENERIC_LOCAL_H */
76
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