5e97b9309b
This series extena and standardises local_t operations on each architecture, allowing a rich set of atomic operations to be done on per-cpu data with minimal performance impact. On architectures where there seems to be no difference between the SMP and UP operation (same memory barriers, same LOCKing), local.h simply includes asm-generic/local.h, which removes duplicated code from the current kernel tree. This patch: local_t: architecture independent extension Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
75 lines
3.1 KiB
C
75 lines
3.1 KiB
C
#ifndef _ASM_GENERIC_LOCAL_H
|
|
#define _ASM_GENERIC_LOCAL_H
|
|
|
|
#include <linux/percpu.h>
|
|
#include <linux/hardirq.h>
|
|
#include <asm/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))
|
|
|
|
/* Use these for per-cpu local_t variables: on some archs they are
|
|
* much more efficient than these naive implementations. Note they take
|
|
* a variable (eg. mystruct.foo), not an address.
|
|
*/
|
|
#define cpu_local_read(l) local_read(&__get_cpu_var(l))
|
|
#define cpu_local_set(l, i) local_set(&__get_cpu_var(l), (i))
|
|
#define cpu_local_inc(l) local_inc(&__get_cpu_var(l))
|
|
#define cpu_local_dec(l) local_dec(&__get_cpu_var(l))
|
|
#define cpu_local_add(i, l) local_add((i), &__get_cpu_var(l))
|
|
#define cpu_local_sub(i, l) local_sub((i), &__get_cpu_var(l))
|
|
|
|
/* Non-atomic increments, ie. preemption disabled and won't be touched
|
|
* in interrupt, etc. Some archs can optimize this case well.
|
|
*/
|
|
#define __cpu_local_inc(l) __local_inc(&__get_cpu_var(l))
|
|
#define __cpu_local_dec(l) __local_dec(&__get_cpu_var(l))
|
|
#define __cpu_local_add(i, l) __local_add((i), &__get_cpu_var(l))
|
|
#define __cpu_local_sub(i, l) __local_sub((i), &__get_cpu_var(l))
|
|
|
|
#endif /* _ASM_GENERIC_LOCAL_H */
|