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[PATCH] i386: generic cmpxchg

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- Make cmpxchg generally available on the i386 platform.

- Provide emulation of cmpxchg suitable for uniprocessor if built and run on
  386.

From: Christoph Lameter <clameter@sgi.com>

- Cut down patch and small style changes.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin
2005-11-13 16:07:23 -08:00
committed by Linus Torvalds
parent dbdf65b1b7
commit 53e86b91b7
2 changed files with 87 additions and 3 deletions
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48
arch/i386/kernel/cpu/intel.c
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@@ -6,6 +6,7 @@
#include <linux/bitops.h>
#include <linux/smp.h>
#include <linux/thread_info.h>
#include <linux/module.h>
#include <asm/processor.h>
#include <asm/msr.h>
@@ -264,5 +265,52 @@ __init int intel_cpu_init(void)
return 0;
}
#ifndef CONFIG_X86_CMPXCHG
unsigned long cmpxchg_386_u8(volatile void *ptr, u8 old, u8 new)
{
u8 prev;
unsigned long flags;
/* Poor man's cmpxchg for 386. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u8 *)ptr;
if (prev == old)
*(u8 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_386_u8);
unsigned long cmpxchg_386_u16(volatile void *ptr, u16 old, u16 new)
{
u16 prev;
unsigned long flags;
/* Poor man's cmpxchg for 386. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u16 *)ptr;
if (prev == old)
*(u16 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_386_u16);
unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new)
{
u32 prev;
unsigned long flags;
/* Poor man's cmpxchg for 386. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u32 *)ptr;
if (prev == old)
*(u32 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_386_u32);
#endif
// arch_initcall(intel_cpu_init);