linux/include/asm-generic/cmpxchg-local.h
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   1#ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H
   2#define __ASM_GENERIC_CMPXCHG_LOCAL_H
   3
   4#include <linux/types.h>
   5#include <linux/irqflags.h>
   6
   7extern unsigned long wrong_size_cmpxchg(volatile void *ptr);
   8
   9/*
  10 * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned
  11 * long parameter, supporting various types of architectures.
  12 */
  13static inline unsigned long __cmpxchg_local_generic(volatile void *ptr,
  14                unsigned long old, unsigned long new, int size)
  15{
  16        unsigned long flags, prev;
  17
  18        /*
  19         * Sanity checking, compile-time.
  20         */
  21        if (size == 8 && sizeof(unsigned long) != 8)
  22                wrong_size_cmpxchg(ptr);
  23
  24        raw_local_irq_save(flags);
  25        switch (size) {
  26        case 1: prev = *(u8 *)ptr;
  27                if (prev == old)
  28                        *(u8 *)ptr = (u8)new;
  29                break;
  30        case 2: prev = *(u16 *)ptr;
  31                if (prev == old)
  32                        *(u16 *)ptr = (u16)new;
  33                break;
  34        case 4: prev = *(u32 *)ptr;
  35                if (prev == old)
  36                        *(u32 *)ptr = (u32)new;
  37                break;
  38        case 8: prev = *(u64 *)ptr;
  39                if (prev == old)
  40                        *(u64 *)ptr = (u64)new;
  41                break;
  42        default:
  43                wrong_size_cmpxchg(ptr);
  44        }
  45        raw_local_irq_restore(flags);
  46        return prev;
  47}
  48
  49/*
  50 * Generic version of __cmpxchg64_local. Takes an u64 parameter.
  51 */
  52static inline u64 __cmpxchg64_local_generic(volatile void *ptr,
  53                u64 old, u64 new)
  54{
  55        u64 prev;
  56        unsigned long flags;
  57
  58        raw_local_irq_save(flags);
  59        prev = *(u64 *)ptr;
  60        if (prev == old)
  61                *(u64 *)ptr = new;
  62        raw_local_irq_restore(flags);
  63        return prev;
  64}
  65
  66#endif
  67
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