thr_pspinlock.c revision 331722 
1/*-
2 * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
3 * Copyright (c) 2016 The FreeBSD Foundation
4 * All rights reserved.
5 *
6 * Portions of this software were developed by Konstantin Belousov
7 * under sponsorship from the FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: stable/11/lib/libthr/thread/thr_pspinlock.c 331722 2018-03-29 02:50:57Z eadler $");
33
34#include "namespace.h"
35#include <errno.h>
36#include <stdlib.h>
37#include <pthread.h>
38#include "un-namespace.h"
39
40#include "thr_private.h"
41
42_Static_assert(sizeof(struct pthread_spinlock) <= PAGE_SIZE,
43    "pthread_spinlock is too large for off-page");
44
45#define SPIN_COUNT 100000
46
47__weak_reference(_pthread_spin_init, pthread_spin_init);
48__weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
49__weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
50__weak_reference(_pthread_spin_lock, pthread_spin_lock);
51__weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
52
53int
54_pthread_spin_init(pthread_spinlock_t *lock, int pshared)
55{
56	struct pthread_spinlock	*lck;
57
58	if (lock == NULL)
59		return (EINVAL);
60	if (pshared == PTHREAD_PROCESS_PRIVATE) {
61		lck = malloc(sizeof(struct pthread_spinlock));
62		if (lck == NULL)
63			return (ENOMEM);
64		*lock = lck;
65	} else if (pshared == PTHREAD_PROCESS_SHARED) {
66		lck = __thr_pshared_offpage(lock, 1);
67		if (lck == NULL)
68			return (EFAULT);
69		*lock = THR_PSHARED_PTR;
70	} else {
71		return (EINVAL);
72	}
73	_thr_umutex_init(&lck->s_lock);
74	return (0);
75}
76
77int
78_pthread_spin_destroy(pthread_spinlock_t *lock)
79{
80	void *l;
81	int ret;
82
83	if (lock == NULL || *lock == NULL) {
84		ret = EINVAL;
85	} else if (*lock == THR_PSHARED_PTR) {
86		l = __thr_pshared_offpage(lock, 0);
87		if (l != NULL)
88			__thr_pshared_destroy(l);
89		ret = 0;
90	} else {
91		free(*lock);
92		*lock = NULL;
93		ret = 0;
94	}
95	return (ret);
96}
97
98int
99_pthread_spin_trylock(pthread_spinlock_t *lock)
100{
101	struct pthread_spinlock	*lck;
102
103	if (lock == NULL || *lock == NULL)
104		return (EINVAL);
105	lck = *lock == THR_PSHARED_PTR ? __thr_pshared_offpage(lock, 0) : *lock;
106	if (lck == NULL)
107		return (EINVAL);
108	return (THR_UMUTEX_TRYLOCK(_get_curthread(), &lck->s_lock));
109}
110
111int
112_pthread_spin_lock(pthread_spinlock_t *lock)
113{
114	struct pthread *curthread;
115	struct pthread_spinlock	*lck;
116	int count;
117
118	if (lock == NULL)
119		return (EINVAL);
120	lck = *lock == THR_PSHARED_PTR ? __thr_pshared_offpage(lock, 0) : *lock;
121	if (lck == NULL)
122		return (EINVAL);
123
124	curthread = _get_curthread();
125	count = SPIN_COUNT;
126	while (THR_UMUTEX_TRYLOCK(curthread, &lck->s_lock) != 0) {
127		while (lck->s_lock.m_owner) {
128			if (!_thr_is_smp) {
129				_pthread_yield();
130			} else {
131				CPU_SPINWAIT;
132				if (--count <= 0) {
133					count = SPIN_COUNT;
134					_pthread_yield();
135				}
136			}
137		}
138	}
139	return (0);
140}
141
142int
143_pthread_spin_unlock(pthread_spinlock_t *lock)
144{
145	struct pthread_spinlock	*lck;
146
147	if (lock == NULL)
148		return (EINVAL);
149	lck = *lock == THR_PSHARED_PTR ? __thr_pshared_offpage(lock, 0) : *lock;
150	if (lck == NULL)
151		return (EINVAL);
152	return (THR_UMUTEX_UNLOCK(_get_curthread(), &lck->s_lock));
153}
154