Commit 1b599e76 authored by KaiGai Kohei's avatar KaiGai Kohei Committed by Linus Torvalds

[PATCH] atomic_inc_return() for i386

This patch implements atomic_inc_return() and so on for i386, and includes
runtime check whether CPU is legacy 386.
Signed-off-by: default avatarKaiGai, Kohei <kaigai@ak.jp.nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a33ecfcb
...@@ -2,6 +2,8 @@ ...@@ -2,6 +2,8 @@
#define __ARCH_I386_ATOMIC__ #define __ARCH_I386_ATOMIC__
#include <linux/config.h> #include <linux/config.h>
#include <linux/compiler.h>
#include <asm/processor.h>
/* /*
* Atomic operations that C can't guarantee us. Useful for * Atomic operations that C can't guarantee us. Useful for
...@@ -176,6 +178,46 @@ static __inline__ int atomic_add_negative(int i, atomic_t *v) ...@@ -176,6 +178,46 @@ static __inline__ int atomic_add_negative(int i, atomic_t *v)
return c; return c;
} }
/**
* atomic_add_return - add and return
* @v: pointer of type atomic_t
* @i: integer value to add
*
* Atomically adds @i to @v and returns @i + @v
*/
static __inline__ int atomic_add_return(int i, atomic_t *v)
{
int __i;
#ifdef CONFIG_M386
if(unlikely(boot_cpu_data.x86==3))
goto no_xadd;
#endif
/* Modern 486+ processor */
__i = i;
__asm__ __volatile__(
LOCK "xaddl %0, %1;"
:"=r"(i)
:"m"(v->counter), "0"(i));
return i + __i;
#ifdef CONFIG_M386
no_xadd: /* Legacy 386 processor */
local_irq_disable();
__i = atomic_read(v);
atomic_set(v, i + __i);
local_irq_enable();
return i + __i;
#endif
}
static __inline__ int atomic_sub_return(int i, atomic_t *v)
{
return atomic_add_return(-i,v);
}
#define atomic_inc_return(v) (atomic_add_return(1,v))
#define atomic_dec_return(v) (atomic_sub_return(1,v))
/* These are x86-specific, used by some header files */ /* These are x86-specific, used by some header files */
#define atomic_clear_mask(mask, addr) \ #define atomic_clear_mask(mask, addr) \
__asm__ __volatile__(LOCK "andl %0,%1" \ __asm__ __volatile__(LOCK "andl %0,%1" \
......
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