thr_pspinlock.c revision 174112 
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 174112 2007-11-30 17:20:29Z deischen $
27 */
28
29#include "namespace.h"
30#include <sys/types.h>
31#include <errno.h>
32#include <pthread.h>
33#include <stdint.h>
34#include <stdlib.h>
35#include "un-namespace.h"
36
37#include "atomic_ops.h"
38#include "thr_private.h"
39
40#define SPIN_COUNT 10000
41
42LT10_COMPAT_PRIVATE(_pthread_spin_init);
43LT10_COMPAT_DEFAULT(pthread_spin_init);
44LT10_COMPAT_PRIVATE(_pthread_spin_destroy);
45LT10_COMPAT_DEFAULT(pthread_spin_destroy);
46LT10_COMPAT_PRIVATE(_pthread_spin_trylock);
47LT10_COMPAT_DEFAULT(pthread_spin_trylock);
48LT10_COMPAT_PRIVATE(_pthread_spin_lock);
49LT10_COMPAT_DEFAULT(pthread_spin_lock);
50LT10_COMPAT_PRIVATE(_pthread_spin_unlock);
51LT10_COMPAT_DEFAULT(pthread_spin_unlock);
52
53__weak_reference(_pthread_spin_init, pthread_spin_init);
54__weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
55__weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
56__weak_reference(_pthread_spin_lock, pthread_spin_lock);
57__weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
58
59int
60_pthread_spin_init(pthread_spinlock_t *lock, int pshared)
61{
62	struct pthread_spinlock	*lck;
63	int ret;
64
65	if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
66		ret = EINVAL;
67	else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
68		ret = ENOMEM;
69	else {
70		lck->s_lock = 0;
71		lck->s_owner= NULL;
72		*lock = lck;
73		ret = 0;
74	}
75
76	return (ret);
77}
78
79int
80_pthread_spin_destroy(pthread_spinlock_t *lock)
81{
82	int ret;
83
84	if (lock == NULL || *lock == NULL)
85		ret = EINVAL;
86	else if ((*lock)->s_owner != NULL)
87		ret = EBUSY;
88	else {
89		free(*lock);
90		*lock = NULL;
91		ret = 0;
92	}
93
94	return (ret);
95}
96
97int
98_pthread_spin_trylock(pthread_spinlock_t *lock)
99{
100	struct pthread_spinlock	*lck;
101	struct pthread *self = _pthread_self();
102	int oldval, ret;
103
104	if (lock == NULL || (lck = *lock) == NULL)
105		ret = EINVAL;
106	else if (lck->s_owner == self)
107		ret = EDEADLK;
108	else if (lck->s_lock != 0)
109		ret = EBUSY;
110	else {
111		atomic_swap_int(&(lck)->s_lock, 1, &oldval);
112		if (oldval)
113			ret = EBUSY;
114		else {
115			lck->s_owner = _pthread_self();
116			ret = 0;
117		}
118	}
119	return (ret);
120}
121
122int
123_pthread_spin_lock(pthread_spinlock_t *lock)
124{
125	struct pthread_spinlock	*lck;
126	struct pthread *self = _pthread_self();
127	int count, oldval, ret;
128
129	if (lock == NULL || (lck = *lock) == NULL)
130		ret = EINVAL;
131	else if (lck->s_owner == self)
132		ret = EDEADLK;
133	else {
134		do {
135			count = SPIN_COUNT;
136			while (lck->s_lock) {
137#ifdef __i386__
138				/* tell cpu we are spinning */
139				__asm __volatile("pause");
140#endif
141				if (--count <= 0) {
142					count = SPIN_COUNT;
143					_pthread_yield();
144				}
145			}
146			atomic_swap_int(&(lck)->s_lock, 1, &oldval);
147		} while (oldval);
148
149		lck->s_owner = self;
150		ret = 0;
151	}
152
153	return (ret);
154}
155
156int
157_pthread_spin_unlock(pthread_spinlock_t *lock)
158{
159	struct pthread_spinlock	*lck;
160	int ret;
161
162	if (lock == NULL || (lck = *lock) == NULL)
163		ret = EINVAL;
164	else {
165		if (lck->s_owner != _pthread_self())
166			ret = EPERM;
167		else {
168			lck->s_owner = NULL;
169			atomic_swap_int(&lck->s_lock, 0, &ret);
170			ret = 0;
171		}
172	}
173
174	return (ret);
175}
176
177