thr_pspinlock.c revision 156611 
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
175