thr_pspinlock.c revision 161068
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/libthr/thread/thr_pspinlock.c 161068 2006-08-08 04:42:41Z davidxu $
27 */
28
29#include "namespace.h"
30#include <errno.h>
31#include <stdlib.h>
32#include <pthread.h>
33#include "un-namespace.h"
34
35#include "thr_private.h"
36
37#define SPIN_COUNT 100000
38
39__weak_reference(_pthread_spin_init, pthread_spin_init);
40__weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
41__weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
42__weak_reference(_pthread_spin_lock, pthread_spin_lock);
43__weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
44
45int
46_pthread_spin_init(pthread_spinlock_t *lock, int pshared)
47{
48	struct pthread_spinlock	*lck;
49	int ret;
50
51	if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
52		ret = EINVAL;
53	else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
54		ret = ENOMEM;
55	else {
56		_thr_umtx_init(&lck->s_lock);
57		*lock = lck;
58		ret = 0;
59	}
60
61	return (ret);
62}
63
64int
65_pthread_spin_destroy(pthread_spinlock_t *lock)
66{
67	int ret;
68
69	if (lock == NULL || *lock == NULL)
70		ret = EINVAL;
71	else {
72		free(*lock);
73		*lock = NULL;
74		ret = 0;
75	}
76
77	return (ret);
78}
79
80int
81_pthread_spin_trylock(pthread_spinlock_t *lock)
82{
83	struct pthread *curthread = _get_curthread();
84	struct pthread_spinlock	*lck;
85	int ret;
86
87	if (lock == NULL || (lck = *lock) == NULL)
88		ret = EINVAL;
89	else
90		ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock);
91	return (ret);
92}
93
94int
95_pthread_spin_lock(pthread_spinlock_t *lock)
96{
97	struct pthread *curthread = _get_curthread();
98	struct pthread_spinlock	*lck;
99	int ret, count;
100
101	if (lock == NULL || (lck = *lock) == NULL)
102		ret = EINVAL;
103	else {
104		count = SPIN_COUNT;
105		while ((ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock)) != 0) {
106			while (lck->s_lock) {
107				if (_thr_smp_cpus <= 1) {
108					_pthread_yield();
109				} else {
110#if defined(__i386__) || defined(__x86_64__)
111					/* tell cpu we are spinning */
112					__asm __volatile("pause");
113#endif
114					if (--count <= 0) {
115						count = SPIN_COUNT;
116						_pthread_yield();
117					}
118				}
119			}
120		}
121		ret = 0;
122	}
123
124	return (ret);
125}
126
127int
128_pthread_spin_unlock(pthread_spinlock_t *lock)
129{
130	struct pthread *curthread = _get_curthread();
131	struct pthread_spinlock	*lck;
132	int ret;
133
134	if (lock == NULL || (lck = *lock) == NULL)
135		ret = EINVAL;
136	else {
137		ret = THR_UMTX_UNLOCK(curthread, &lck->s_lock);
138	}
139	return (ret);
140}
141