linux/include/asm-x86_64/local.h
Andi Kleen 1c1734090e [PATCH] x86_64: Correct wrong comment in local.h
local_t is actually a win over atomic_t because it does not need lock
prefixes.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16 15:25:08 -07:00

75 lines
1.9 KiB
C

#ifndef _ARCH_X8664_LOCAL_H
#define _ARCH_X8664_LOCAL_H
#include <linux/percpu.h>
typedef struct
{
volatile unsigned int counter;
} local_t;
#define LOCAL_INIT(i) { (i) }
#define local_read(v) ((v)->counter)
#define local_set(v,i) (((v)->counter) = (i))
static __inline__ void local_inc(local_t *v)
{
__asm__ __volatile__(
"incl %0"
:"=m" (v->counter)
:"m" (v->counter));
}
static __inline__ void local_dec(local_t *v)
{
__asm__ __volatile__(
"decl %0"
:"=m" (v->counter)
:"m" (v->counter));
}
static __inline__ void local_add(unsigned long i, local_t *v)
{
__asm__ __volatile__(
"addl %1,%0"
:"=m" (v->counter)
:"ir" (i), "m" (v->counter));
}
static __inline__ void local_sub(unsigned long i, local_t *v)
{
__asm__ __volatile__(
"subl %1,%0"
:"=m" (v->counter)
:"ir" (i), "m" (v->counter));
}
/* On x86-64 these are better than the atomic variants on SMP kernels
because they dont use a lock prefix. */
#define __local_inc(l) local_inc(l)
#define __local_dec(l) local_dec(l)
#define __local_add(i,l) local_add((i),(l))
#define __local_sub(i,l) local_sub((i),(l))
/* 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, not an address.
*
* This could be done better if we moved the per cpu data directly
* after GS.
*/
#define cpu_local_read(v) local_read(&__get_cpu_var(v))
#define cpu_local_set(v, i) local_set(&__get_cpu_var(v), (i))
#define cpu_local_inc(v) local_inc(&__get_cpu_var(v))
#define cpu_local_dec(v) local_dec(&__get_cpu_var(v))
#define cpu_local_add(i, v) local_add((i), &__get_cpu_var(v))
#define cpu_local_sub(i, v) local_sub((i), &__get_cpu_var(v))
#define __cpu_local_inc(v) cpu_local_inc(v)
#define __cpu_local_dec(v) cpu_local_dec(v)
#define __cpu_local_add(i, v) cpu_local_add((i), (v))
#define __cpu_local_sub(i, v) cpu_local_sub((i), (v))
#endif /* _ARCH_I386_LOCAL_H */