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1 | /* |
2 | * Generic UP xchg and cmpxchg using interrupt disablement. Does not |
3 | * support SMP. |
4 | */ |
5 | |
6 | #ifndef __ASM_GENERIC_CMPXCHG_H |
7 | #define __ASM_GENERIC_CMPXCHG_H |
8 | |
9 | #ifdef CONFIG_SMP |
10 | #error "Cannot use generic cmpxchg on SMP" |
11 | #endif |
12 | |
13 | #include <linux/types.h> |
14 | #include <linux/irqflags.h> |
15 | |
16 | #ifndef xchg |
17 | |
18 | /* |
19 | * This function doesn't exist, so you'll get a linker error if |
20 | * something tries to do an invalidly-sized xchg(). |
21 | */ |
22 | extern void __xchg_called_with_bad_pointer(void); |
23 | |
24 | static inline |
25 | unsigned long __xchg(unsigned long x, volatile void *ptr, int size) |
26 | { |
27 | unsigned long ret, flags; |
28 | |
29 | switch (size) { |
30 | case 1: |
31 | #ifdef __xchg_u8 |
32 | return __xchg_u8(x, ptr); |
33 | #else |
34 | local_irq_save(flags); |
35 | ret = *(volatile u8 *)ptr; |
36 | *(volatile u8 *)ptr = x; |
37 | local_irq_restore(flags); |
38 | return ret; |
39 | #endif /* __xchg_u8 */ |
40 | |
41 | case 2: |
42 | #ifdef __xchg_u16 |
43 | return __xchg_u16(x, ptr); |
44 | #else |
45 | local_irq_save(flags); |
46 | ret = *(volatile u16 *)ptr; |
47 | *(volatile u16 *)ptr = x; |
48 | local_irq_restore(flags); |
49 | return ret; |
50 | #endif /* __xchg_u16 */ |
51 | |
52 | case 4: |
53 | #ifdef __xchg_u32 |
54 | return __xchg_u32(x, ptr); |
55 | #else |
56 | local_irq_save(flags); |
57 | ret = *(volatile u32 *)ptr; |
58 | *(volatile u32 *)ptr = x; |
59 | local_irq_restore(flags); |
60 | return ret; |
61 | #endif /* __xchg_u32 */ |
62 | |
63 | #ifdef CONFIG_64BIT |
64 | case 8: |
65 | #ifdef __xchg_u64 |
66 | return __xchg_u64(x, ptr); |
67 | #else |
68 | local_irq_save(flags); |
69 | ret = *(volatile u64 *)ptr; |
70 | *(volatile u64 *)ptr = x; |
71 | local_irq_restore(flags); |
72 | return ret; |
73 | #endif /* __xchg_u64 */ |
74 | #endif /* CONFIG_64BIT */ |
75 | |
76 | default: |
77 | __xchg_called_with_bad_pointer(); |
78 | return x; |
79 | } |
80 | } |
81 | |
82 | #define xchg(ptr, x) \ |
83 | ((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))) |
84 | |
85 | #endif /* xchg */ |
86 | |
87 | /* |
88 | * Atomic compare and exchange. |
89 | * |
90 | * Do not define __HAVE_ARCH_CMPXCHG because we want to use it to check whether |
91 | * a cmpxchg primitive faster than repeated local irq save/restore exists. |
92 | */ |
93 | #include <asm-generic/cmpxchg-local.h> |
94 | |
95 | #ifndef cmpxchg_local |
96 | #define cmpxchg_local(ptr, o, n) \ |
97 | ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ |
98 | (unsigned long)(n), sizeof(*(ptr)))) |
99 | #endif |
100 | |
101 | #ifndef cmpxchg64_local |
102 | #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) |
103 | #endif |
104 | |
105 | #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n)) |
106 | #define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n)) |
107 | |
108 | #endif /* __ASM_GENERIC_CMPXCHG_H */ |
109 |
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v2.6.34-rc5
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