swh:1:snp:32555a3fd8878f019c2ebd6c964bc1edcaeff337
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Tip revision: 3b2f64d00c46e1e4e9bd0bb9bb12619adac27a4b authored by Linus Torvalds on 21 July 2013, 19:05:29 UTC
Linux 3.11-rc2
Tip revision: 3b2f64d
cmpxchg-local.h
#ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H
#define __ASM_GENERIC_CMPXCHG_LOCAL_H

#include <linux/types.h>
#include <linux/irqflags.h>

extern unsigned long wrong_size_cmpxchg(volatile void *ptr);

/*
 * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned
 * long parameter, supporting various types of architectures.
 */
static inline unsigned long __cmpxchg_local_generic(volatile void *ptr,
		unsigned long old, unsigned long new, int size)
{
	unsigned long flags, prev;

	/*
	 * Sanity checking, compile-time.
	 */
	if (size == 8 && sizeof(unsigned long) != 8)
		wrong_size_cmpxchg(ptr);

	raw_local_irq_save(flags);
	switch (size) {
	case 1: prev = *(u8 *)ptr;
		if (prev == old)
			*(u8 *)ptr = (u8)new;
		break;
	case 2: prev = *(u16 *)ptr;
		if (prev == old)
			*(u16 *)ptr = (u16)new;
		break;
	case 4: prev = *(u32 *)ptr;
		if (prev == old)
			*(u32 *)ptr = (u32)new;
		break;
	case 8: prev = *(u64 *)ptr;
		if (prev == old)
			*(u64 *)ptr = (u64)new;
		break;
	default:
		wrong_size_cmpxchg(ptr);
	}
	raw_local_irq_restore(flags);
	return prev;
}

/*
 * Generic version of __cmpxchg64_local. Takes an u64 parameter.
 */
static inline u64 __cmpxchg64_local_generic(volatile void *ptr,
		u64 old, u64 new)
{
	u64 prev;
	unsigned long flags;

	raw_local_irq_save(flags);
	prev = *(u64 *)ptr;
	if (prev == old)
		*(u64 *)ptr = new;
	raw_local_irq_restore(flags);
	return prev;
}

#endif
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