diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 05:20:03 -0400 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 05:20:03 -0400 |
commit | 96a388de5dc53a8b234b3fd41f3ae2cedc9ffd42 (patch) | |
tree | d947a467aa2da3140279617bc4b9b101640d7bf4 /include/asm-x86/mutex_32.h | |
parent | 27bd0c955648646abf2a353a8371d28c37bcd982 (diff) |
i386/x86_64: move headers to include/asm-x86
Move the headers to include/asm-x86 and fixup the
header install make rules
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-x86/mutex_32.h')
-rw-r--r-- | include/asm-x86/mutex_32.h | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/include/asm-x86/mutex_32.h b/include/asm-x86/mutex_32.h new file mode 100644 index 000000000000..7a17d9e58ad6 --- /dev/null +++ b/include/asm-x86/mutex_32.h | |||
@@ -0,0 +1,130 @@ | |||
1 | /* | ||
2 | * Assembly implementation of the mutex fastpath, based on atomic | ||
3 | * decrement/increment. | ||
4 | * | ||
5 | * started by Ingo Molnar: | ||
6 | * | ||
7 | * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | ||
8 | */ | ||
9 | #ifndef _ASM_MUTEX_H | ||
10 | #define _ASM_MUTEX_H | ||
11 | |||
12 | #include "asm/alternative.h" | ||
13 | |||
14 | /** | ||
15 | * __mutex_fastpath_lock - try to take the lock by moving the count | ||
16 | * from 1 to a 0 value | ||
17 | * @count: pointer of type atomic_t | ||
18 | * @fn: function to call if the original value was not 1 | ||
19 | * | ||
20 | * Change the count from 1 to a value lower than 1, and call <fn> if it | ||
21 | * wasn't 1 originally. This function MUST leave the value lower than 1 | ||
22 | * even when the "1" assertion wasn't true. | ||
23 | */ | ||
24 | #define __mutex_fastpath_lock(count, fail_fn) \ | ||
25 | do { \ | ||
26 | unsigned int dummy; \ | ||
27 | \ | ||
28 | typecheck(atomic_t *, count); \ | ||
29 | typecheck_fn(fastcall void (*)(atomic_t *), fail_fn); \ | ||
30 | \ | ||
31 | __asm__ __volatile__( \ | ||
32 | LOCK_PREFIX " decl (%%eax) \n" \ | ||
33 | " jns 1f \n" \ | ||
34 | " call "#fail_fn" \n" \ | ||
35 | "1: \n" \ | ||
36 | \ | ||
37 | :"=a" (dummy) \ | ||
38 | : "a" (count) \ | ||
39 | : "memory", "ecx", "edx"); \ | ||
40 | } while (0) | ||
41 | |||
42 | |||
43 | /** | ||
44 | * __mutex_fastpath_lock_retval - try to take the lock by moving the count | ||
45 | * from 1 to a 0 value | ||
46 | * @count: pointer of type atomic_t | ||
47 | * @fail_fn: function to call if the original value was not 1 | ||
48 | * | ||
49 | * Change the count from 1 to a value lower than 1, and call <fail_fn> if it | ||
50 | * wasn't 1 originally. This function returns 0 if the fastpath succeeds, | ||
51 | * or anything the slow path function returns | ||
52 | */ | ||
53 | static inline int | ||
54 | __mutex_fastpath_lock_retval(atomic_t *count, | ||
55 | int fastcall (*fail_fn)(atomic_t *)) | ||
56 | { | ||
57 | if (unlikely(atomic_dec_return(count) < 0)) | ||
58 | return fail_fn(count); | ||
59 | else | ||
60 | return 0; | ||
61 | } | ||
62 | |||
63 | /** | ||
64 | * __mutex_fastpath_unlock - try to promote the mutex from 0 to 1 | ||
65 | * @count: pointer of type atomic_t | ||
66 | * @fail_fn: function to call if the original value was not 0 | ||
67 | * | ||
68 | * try to promote the mutex from 0 to 1. if it wasn't 0, call <fail_fn>. | ||
69 | * In the failure case, this function is allowed to either set the value | ||
70 | * to 1, or to set it to a value lower than 1. | ||
71 | * | ||
72 | * If the implementation sets it to a value of lower than 1, the | ||
73 | * __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs | ||
74 | * to return 0 otherwise. | ||
75 | */ | ||
76 | #define __mutex_fastpath_unlock(count, fail_fn) \ | ||
77 | do { \ | ||
78 | unsigned int dummy; \ | ||
79 | \ | ||
80 | typecheck(atomic_t *, count); \ | ||
81 | typecheck_fn(fastcall void (*)(atomic_t *), fail_fn); \ | ||
82 | \ | ||
83 | __asm__ __volatile__( \ | ||
84 | LOCK_PREFIX " incl (%%eax) \n" \ | ||
85 | " jg 1f \n" \ | ||
86 | " call "#fail_fn" \n" \ | ||
87 | "1: \n" \ | ||
88 | \ | ||
89 | :"=a" (dummy) \ | ||
90 | : "a" (count) \ | ||
91 | : "memory", "ecx", "edx"); \ | ||
92 | } while (0) | ||
93 | |||
94 | #define __mutex_slowpath_needs_to_unlock() 1 | ||
95 | |||
96 | /** | ||
97 | * __mutex_fastpath_trylock - try to acquire the mutex, without waiting | ||
98 | * | ||
99 | * @count: pointer of type atomic_t | ||
100 | * @fail_fn: fallback function | ||
101 | * | ||
102 | * Change the count from 1 to a value lower than 1, and return 0 (failure) | ||
103 | * if it wasn't 1 originally, or return 1 (success) otherwise. This function | ||
104 | * MUST leave the value lower than 1 even when the "1" assertion wasn't true. | ||
105 | * Additionally, if the value was < 0 originally, this function must not leave | ||
106 | * it to 0 on failure. | ||
107 | */ | ||
108 | static inline int | ||
109 | __mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) | ||
110 | { | ||
111 | /* | ||
112 | * We have two variants here. The cmpxchg based one is the best one | ||
113 | * because it never induce a false contention state. It is included | ||
114 | * here because architectures using the inc/dec algorithms over the | ||
115 | * xchg ones are much more likely to support cmpxchg natively. | ||
116 | * | ||
117 | * If not we fall back to the spinlock based variant - that is | ||
118 | * just as efficient (and simpler) as a 'destructive' probing of | ||
119 | * the mutex state would be. | ||
120 | */ | ||
121 | #ifdef __HAVE_ARCH_CMPXCHG | ||
122 | if (likely(atomic_cmpxchg(count, 1, 0) == 1)) | ||
123 | return 1; | ||
124 | return 0; | ||
125 | #else | ||
126 | return fail_fn(count); | ||
127 | #endif | ||
128 | } | ||
129 | |||
130 | #endif | ||