cmpxchg.c

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/*
 * cmpxchg*() fallbacks for CPU not supporting these instructions
 */

#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/module.h>

#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