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