LXR linux/include/asm-generic/cmpxchg-local.h

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