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Diffstat (limited to 'include/asm-generic/local.h')
-rw-r--r-- | include/asm-generic/local.h | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/include/asm-generic/local.h b/include/asm-generic/local.h new file mode 100644 index 00000000..9ceb03b4 --- /dev/null +++ b/include/asm-generic/local.h @@ -0,0 +1,55 @@ +#ifndef _ASM_GENERIC_LOCAL_H +#define _ASM_GENERIC_LOCAL_H + +#include <linux/percpu.h> +#include <linux/atomic.h> +#include <asm/types.h> + +/* + * A signed long type for operations which are atomic for a single CPU. + * Usually used in combination with per-cpu variables. + * + * This is the default implementation, which uses atomic_long_t. Which is + * rather pointless. The whole point behind local_t is that some processors + * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs + * running on this CPU. local_t allows exploitation of such capabilities. + */ + +/* Implement in terms of atomics. */ + +/* Don't use typedef: don't want them to be mixed with atomic_t's. */ +typedef struct +{ + atomic_long_t a; +} local_t; + +#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) } + +#define local_read(l) atomic_long_read(&(l)->a) +#define local_set(l,i) atomic_long_set((&(l)->a),(i)) +#define local_inc(l) atomic_long_inc(&(l)->a) +#define local_dec(l) atomic_long_dec(&(l)->a) +#define local_add(i,l) atomic_long_add((i),(&(l)->a)) +#define local_sub(i,l) atomic_long_sub((i),(&(l)->a)) + +#define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a)) +#define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a) +#define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a) +#define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a)) +#define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a)) +#define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a)) +#define local_inc_return(l) atomic_long_inc_return(&(l)->a) + +#define local_cmpxchg(l, o, n) atomic_long_cmpxchg((&(l)->a), (o), (n)) +#define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n)) +#define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u)) +#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a) + +/* Non-atomic variants, ie. preemption disabled and won't be touched + * in interrupt, etc. Some archs can optimize this case well. */ +#define __local_inc(l) local_set((l), local_read(l) + 1) +#define __local_dec(l) local_set((l), local_read(l) - 1) +#define __local_add(i,l) local_set((l), local_read(l) + (i)) +#define __local_sub(i,l) local_set((l), local_read(l) - (i)) + +#endif /* _ASM_GENERIC_LOCAL_H */ |