1/*-
2 * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
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 * $FreeBSD: head/lib/libkse/thread/thr_pspinlock.c 156611 2006-03-13 00:59:51Z deischen $
27 */
28
29#include <sys/types.h>
30#include <errno.h>
31#include <pthread.h>
32#include <stdint.h>
33#include <stdlib.h>
34
35#include "atomic_ops.h"
36#include "thr_private.h"
37
38#define SPIN_COUNT 10000
39
40LT10_COMPAT_PRIVATE(_pthread_spin_init);
41LT10_COMPAT_DEFAULT(pthread_spin_init);
42LT10_COMPAT_PRIVATE(_pthread_spin_destroy);
43LT10_COMPAT_DEFAULT(pthread_spin_destroy);
44LT10_COMPAT_PRIVATE(_pthread_spin_trylock);
45LT10_COMPAT_DEFAULT(pthread_spin_trylock);
46LT10_COMPAT_PRIVATE(_pthread_spin_lock);
47LT10_COMPAT_DEFAULT(pthread_spin_lock);
48LT10_COMPAT_PRIVATE(_pthread_spin_unlock);
49LT10_COMPAT_DEFAULT(pthread_spin_unlock);
50
51__weak_reference(_pthread_spin_init, pthread_spin_init);
52__weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
53__weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
54__weak_reference(_pthread_spin_lock, pthread_spin_lock);
55__weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
56
57int
58_pthread_spin_init(pthread_spinlock_t *lock, int pshared)
59{
60 struct pthread_spinlock *lck;
61 int ret;
62
63 if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
64 ret = EINVAL;
65 else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
66 ret = ENOMEM;
67 else {
68 lck->s_lock = 0;
69 lck->s_owner= NULL;
70 *lock = lck;
71 ret = 0;
72 }
73
74 return (ret);
75}
76
77int
78_pthread_spin_destroy(pthread_spinlock_t *lock)
79{
80 int ret;
81
82 if (lock == NULL || *lock == NULL)
83 ret = EINVAL;
84 else if ((*lock)->s_owner != NULL)
85 ret = EBUSY;
86 else {
87 free(*lock);
88 *lock = NULL;
89 ret = 0;
90 }
91
92 return (ret);
93}
94
95int
96_pthread_spin_trylock(pthread_spinlock_t *lock)
97{
98 struct pthread_spinlock *lck;
99 struct pthread *self = _pthread_self();
100 int oldval, ret;
101
102 if (lock == NULL || (lck = *lock) == NULL)
103 ret = EINVAL;
104 else if (lck->s_owner == self)
105 ret = EDEADLK;
106 else if (lck->s_lock != 0)
107 ret = EBUSY;
108 else {
109 atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
110 if (oldval)
111 ret = EBUSY;
112 else {
113 lck->s_owner = _pthread_self();
114 ret = 0;
115 }
116 }
117 return (ret);
118}
119
120int
121_pthread_spin_lock(pthread_spinlock_t *lock)
122{
123 struct pthread_spinlock *lck;
124 struct pthread *self = _pthread_self();
125 int count, oldval, ret;
126
127 if (lock == NULL || (lck = *lock) == NULL)
128 ret = EINVAL;
129 else if (lck->s_owner == self)
130 ret = EDEADLK;
131 else {
132 do {
133 count = SPIN_COUNT;
134 while (lck->s_lock) {
135#ifdef __i386__
136 /* tell cpu we are spinning */
137 __asm __volatile("pause");
138#endif
139 if (--count <= 0) {
140 count = SPIN_COUNT;
141 _pthread_yield();
142 }
143 }
144 atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
145 } while (oldval);
146
147 lck->s_owner = self;
148 ret = 0;
149 }
150
151 return (ret);
152}
153
154int
155_pthread_spin_unlock(pthread_spinlock_t *lock)
156{
157 struct pthread_spinlock *lck;
158 int ret;
159
160 if (lock == NULL || (lck = *lock) == NULL)
161 ret = EINVAL;
162 else {
163 if (lck->s_owner != _pthread_self())
164 ret = EPERM;
165 else {
166 lck->s_owner = NULL;
167 atomic_swap_int((int *)&lck->s_lock, 0, &ret);
168 ret = 0;
169 }
170 }
171
172 return (ret);
173}
174