1#ifndef __ASM_GENERIC_CMPXCHG_H
 2#define __ASM_GENERIC_CMPXCHG_H
 3
 4/*
 5 * Generic cmpxchg
 6 *
 7 * Uses the local cmpxchg. Does not support SMP.
 8 */
 9#ifdef CONFIG_SMP
10#error "Cannot use generic cmpxchg on SMP"
11#endif
12
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
13/*
14 * Atomic compare and exchange.
15 *
16 * Do not define __HAVE_ARCH_CMPXCHG because we want to use it to check whether
17 * a cmpxchg primitive faster than repeated local irq save/restore exists.
18 */
 
 
19#define cmpxchg(ptr, o, n)	cmpxchg_local((ptr), (o), (n))
20#define cmpxchg64(ptr, o, n)	cmpxchg64_local((ptr), (o), (n))
21
22#endif

 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 */
22extern void __xchg_called_with_bad_pointer(void);
23
24static inline
25unsigned 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#define cmpxchg(ptr, o, n)	cmpxchg_local((ptr), (o), (n))
96#define cmpxchg64(ptr, o, n)	cmpxchg64_local((ptr), (o), (n))
97
98#endif /* __ASM_GENERIC_CMPXCHG_H */