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[SPARC]: Emulate cmpxchg like parisc

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Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kyle McMartin 2007-05-29 02:51:13 -07:00 committed by David S. Miller
parent 679292993c
commit 6197fe4d72
2 changed files with 53 additions and 0 deletions
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15
arch/sparc/lib/atomic32.c
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@ -2,6 +2,7 @@
* atomic32.c: 32-bit atomic_t implementation
*
* Copyright (C) 2004 Keith M Wesolowski
* Copyright (C) 2007 Kyle McMartin
*
* Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
*/
@ -117,3 +118,17 @@ unsigned long ___change_bit(unsigned long *addr, unsigned long mask)
return old & mask;
}
EXPORT_SYMBOL(___change_bit);
unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
{
unsigned long flags;
u32 prev;
spin_lock_irqsave(ATOMIC_HASH(addr), flags);
if ((prev = *ptr) == old)
*ptr = new;
spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
return (unsigned long)prev;
}
EXPORT_SYMBOL(__cmpxchg_u32);

38
include/asm-sparc/atomic.h
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@ -2,6 +2,7 @@
*
* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
* Copyright (C) 2007 Kyle McMartin (kyle@parisc-linux.org)
*
* Additions by Keith M Wesolowski (wesolows@foobazco.org) based
* on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.
@ -10,11 +11,48 @@
#ifndef __ARCH_SPARC_ATOMIC__
#define __ARCH_SPARC_ATOMIC__
#include <linux/types.h>
typedef struct { volatile int counter; } atomic_t;
#ifdef __KERNEL__
/* Emulate cmpxchg() the same way we emulate atomics,
* by hashing the object address and indexing into an array
* of spinlocks to get a bit of performance...
*
* See arch/sparc/lib/atomic32.c for implementation.
*
* Cribbed from <asm-parisc/atomic.h>
*/
#define __HAVE_ARCH_CMPXCHG 1
/* bug catcher for when unsupported size is used - won't link */
extern void __cmpxchg_called_with_bad_pointer(void);
/* we only need to support cmpxchg of a u32 on sparc */
extern unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
/* don't worry...optimizer will get rid of most of this */
static __inline__ unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
{
switch(size) {
case 4:
return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
default:
__cmpxchg_called_with_bad_pointer();
break;
}
return old;
}
#define cmpxchg(ptr,o,n) ({ \
__typeof__(*(ptr)) _o_ = (o); \
__typeof__(*(ptr)) _n_ = (n); \
(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
(unsigned long)_n_, sizeof(*(ptr))); \
})
#define ATOMIC_INIT(i) { (i) }
extern int __atomic_add_return(int, atomic_t *);