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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 
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
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