1 /*
2 * Copyright 2010-2015 Samy Al Bahra.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #ifndef CK_SPINLOCK_FAS_H
28 #define CK_SPINLOCK_FAS_H
29
30 #include <ck_backoff.h>
31 #include <ck_cc.h>
32 #include <ck_elide.h>
33 #include <ck_pr.h>
34 #include <ck_stdbool.h>
35
36 #ifndef CK_F_SPINLOCK_FAS
37 #define CK_F_SPINLOCK_FAS
38
39 struct ck_spinlock_fas {
40 unsigned int value;
41 };
42 typedef struct ck_spinlock_fas ck_spinlock_fas_t;
43
44 #define CK_SPINLOCK_FAS_INITIALIZER {false}
45
46 CK_CC_INLINE static void
ck_spinlock_fas_init(struct ck_spinlock_fas * lock)47 ck_spinlock_fas_init(struct ck_spinlock_fas *lock)
48 {
49
50 lock->value = false;
51 ck_pr_barrier();
52 return;
53 }
54
55 CK_CC_INLINE static bool
ck_spinlock_fas_trylock(struct ck_spinlock_fas * lock)56 ck_spinlock_fas_trylock(struct ck_spinlock_fas *lock)
57 {
58 bool value;
59
60 value = ck_pr_fas_uint(&lock->value, true);
61 ck_pr_fence_lock();
62
63 return !value;
64 }
65
66 CK_CC_INLINE static bool
ck_spinlock_fas_locked(struct ck_spinlock_fas * lock)67 ck_spinlock_fas_locked(struct ck_spinlock_fas *lock)
68 {
69 bool r;
70
71 r = ck_pr_load_uint(&lock->value);
72 ck_pr_fence_acquire();
73 return r;
74 }
75
76 CK_CC_INLINE static void
ck_spinlock_fas_lock(struct ck_spinlock_fas * lock)77 ck_spinlock_fas_lock(struct ck_spinlock_fas *lock)
78 {
79
80 while (CK_CC_UNLIKELY(ck_pr_fas_uint(&lock->value, true) == true)) {
81 do {
82 ck_pr_stall();
83 } while (ck_pr_load_uint(&lock->value) == true);
84 }
85
86 ck_pr_fence_lock();
87 return;
88 }
89
90 CK_CC_INLINE static void
ck_spinlock_fas_lock_eb(struct ck_spinlock_fas * lock)91 ck_spinlock_fas_lock_eb(struct ck_spinlock_fas *lock)
92 {
93 ck_backoff_t backoff = CK_BACKOFF_INITIALIZER;
94
95 while (ck_pr_fas_uint(&lock->value, true) == true)
96 ck_backoff_eb(&backoff);
97
98 ck_pr_fence_lock();
99 return;
100 }
101
102 CK_CC_INLINE static void
ck_spinlock_fas_unlock(struct ck_spinlock_fas * lock)103 ck_spinlock_fas_unlock(struct ck_spinlock_fas *lock)
104 {
105
106 ck_pr_fence_unlock();
107 ck_pr_store_uint(&lock->value, false);
108 return;
109 }
110
111 CK_ELIDE_PROTOTYPE(ck_spinlock_fas, ck_spinlock_fas_t,
112 ck_spinlock_fas_locked, ck_spinlock_fas_lock,
113 ck_spinlock_fas_locked, ck_spinlock_fas_unlock)
114
115 CK_ELIDE_TRYLOCK_PROTOTYPE(ck_spinlock_fas, ck_spinlock_fas_t,
116 ck_spinlock_fas_locked, ck_spinlock_fas_trylock)
117
118 #endif /* CK_F_SPINLOCK_FAS */
119 #endif /* CK_SPINLOCK_FAS_H */
120