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
39struct ck_spinlock_fas {
40	unsigned int value;
41};
42typedef struct ck_spinlock_fas ck_spinlock_fas_t;
43
44#define CK_SPINLOCK_FAS_INITIALIZER {false}
45
46CK_CC_INLINE static void
47ck_spinlock_fas_init(struct ck_spinlock_fas *lock)
48{
49
50	lock->value = false;
51	ck_pr_barrier();
52	return;
53}
54
55CK_CC_INLINE static bool
56ck_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
66CK_CC_INLINE static bool
67ck_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
76CK_CC_INLINE static void
77ck_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
90CK_CC_INLINE static void
91ck_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
102CK_CC_INLINE static void
103ck_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
111CK_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
115CK_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