root/include/asm-generic/cmpxchg-local.h

INCLUDED FROM

DEFINITIONS

1. __cmpxchg_local_generic
2. __cmpxchg64_local_generic

#ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H
#define __ASM_GENERIC_CMPXCHG_LOCAL_H

#include <linux/types.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);

        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);
        }
        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;

        local_irq_save(flags);
        prev = *(u64 *)ptr;
        if (prev == old)
                *(u64 *)ptr = new;
        local_irq_restore(flags);
        return prev;
}

#endif