Commit | Line | Data |
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2acbb8c6 | 1 | /* |
a454c2f3 | 2 | * ia64 implementation of the mutex fastpath. |
2acbb8c6 | 3 | * |
a454c2f3 CK |
4 | * Copyright (C) 2006 Ken Chen <kenneth.w.chen@intel.com> |
5 | * | |
6 | */ | |
7 | ||
8 | #ifndef _ASM_MUTEX_H | |
9 | #define _ASM_MUTEX_H | |
10 | ||
11 | /** | |
12 | * __mutex_fastpath_lock - try to take the lock by moving the count | |
13 | * from 1 to a 0 value | |
14 | * @count: pointer of type atomic_t | |
15 | * @fail_fn: function to call if the original value was not 1 | |
16 | * | |
17 | * Change the count from 1 to a value lower than 1, and call <fail_fn> if | |
18 | * it wasn't 1 originally. This function MUST leave the value lower than | |
19 | * 1 even when the "1" assertion wasn't true. | |
20 | */ | |
21 | static inline void | |
22 | __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) | |
23 | { | |
24 | if (unlikely(ia64_fetchadd4_acq(count, -1) != 1)) | |
25 | fail_fn(count); | |
26 | } | |
27 | ||
28 | /** | |
29 | * __mutex_fastpath_lock_retval - try to take the lock by moving the count | |
30 | * from 1 to a 0 value | |
31 | * @count: pointer of type atomic_t | |
32 | * @fail_fn: function to call if the original value was not 1 | |
33 | * | |
34 | * Change the count from 1 to a value lower than 1, and call <fail_fn> if | |
35 | * it wasn't 1 originally. This function returns 0 if the fastpath succeeds, | |
36 | * or anything the slow path function returns. | |
37 | */ | |
38 | static inline int | |
39 | __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *)) | |
40 | { | |
41 | if (unlikely(ia64_fetchadd4_acq(count, -1) != 1)) | |
42 | return fail_fn(count); | |
43 | return 0; | |
44 | } | |
45 | ||
46 | /** | |
47 | * __mutex_fastpath_unlock - try to promote the count from 0 to 1 | |
48 | * @count: pointer of type atomic_t | |
49 | * @fail_fn: function to call if the original value was not 0 | |
50 | * | |
51 | * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>. | |
52 | * In the failure case, this function is allowed to either set the value to | |
53 | * 1, or to set it to a value lower than 1. | |
54 | * | |
55 | * If the implementation sets it to a value of lower than 1, then the | |
56 | * __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs | |
57 | * to return 0 otherwise. | |
58 | */ | |
59 | static inline void | |
60 | __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) | |
61 | { | |
62 | int ret = ia64_fetchadd4_rel(count, 1); | |
63 | if (unlikely(ret < 0)) | |
64 | fail_fn(count); | |
65 | } | |
66 | ||
67 | #define __mutex_slowpath_needs_to_unlock() 1 | |
68 | ||
69 | /** | |
70 | * __mutex_fastpath_trylock - try to acquire the mutex, without waiting | |
71 | * | |
72 | * @count: pointer of type atomic_t | |
73 | * @fail_fn: fallback function | |
74 | * | |
75 | * Change the count from 1 to a value lower than 1, and return 0 (failure) | |
76 | * if it wasn't 1 originally, or return 1 (success) otherwise. This function | |
77 | * MUST leave the value lower than 1 even when the "1" assertion wasn't true. | |
78 | * Additionally, if the value was < 0 originally, this function must not leave | |
79 | * it to 0 on failure. | |
80 | * | |
81 | * If the architecture has no effective trylock variant, it should call the | |
82 | * <fail_fn> spinlock-based trylock variant unconditionally. | |
2acbb8c6 | 83 | */ |
a454c2f3 CK |
84 | static inline int |
85 | __mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) | |
86 | { | |
cfab9d0e | 87 | if (cmpxchg_acq(count, 1, 0) == 1) |
a454c2f3 CK |
88 | return 1; |
89 | return 0; | |
90 | } | |
2acbb8c6 | 91 | |
a454c2f3 | 92 | #endif |