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 #include <linux/irqflags.h>
   6
   7 extern 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  */
  13 static 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         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         local_irq_restore(flags);
  46         return prev;
  47 }
  48
  49 /*
  50  * Generic version of __cmpxchg64_local. Takes an u64 parameter.
  51  */
  52 static inline u64 __cmpxchg64_local_generic(volatile void *ptr,
  53                 u64 old, u64 new)
  54 {
  55         u64 prev;
  56         unsigned long flags;
  57
  58         local_irq_save(flags);
  59         prev = *(u64 *)ptr;
  60         if (prev == old)
  61                 *(u64 *)ptr = new;
  62         local_irq_restore(flags);
  63         return prev;
  64 }
  65
  66 #endif