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
   6 extern 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  */
  12 static 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  */
  51 static 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