thr_pspinlock.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
5 * Copyright (c) 2016 The FreeBSD Foundation
6 * All rights reserved.
7 *
8 * Portions of this software were developed by Konstantin Belousov
9 * under sponsorship from the FreeBSD Foundation.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: stable/11/lib/libthr/thread/thr_pspinlock.c 330897 2018-03-14 03:19:51Z eadler $");
35
36#include "namespace.h"
37#include <errno.h>
38#include <stdlib.h>
39#include <pthread.h>
40#include "un-namespace.h"
41
42#include "thr_private.h"
43
44_Static_assert(sizeof(struct pthread_spinlock) <= PAGE_SIZE,
45    "pthread_spinlock is too large for off-page");
46
47#define SPIN_COUNT 100000
48
49__weak_reference(_pthread_spin_init, pthread_spin_init);
50__weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
51__weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
52__weak_reference(_pthread_spin_lock, pthread_spin_lock);
53__weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
54
55int
56_pthread_spin_init(pthread_spinlock_t *lock, int pshared)
57{
58	struct pthread_spinlock	*lck;
59
60	if (lock == NULL)
61		return (EINVAL);
62	if (pshared == PTHREAD_PROCESS_PRIVATE) {
63		lck = malloc(sizeof(struct pthread_spinlock));
64		if (lck == NULL)
65			return (ENOMEM);
66		*lock = lck;
67	} else if (pshared == PTHREAD_PROCESS_SHARED) {
68		lck = __thr_pshared_offpage(lock, 1);
69		if (lck == NULL)
70			return (EFAULT);
71		*lock = THR_PSHARED_PTR;
72	} else {
73		return (EINVAL);
74	}
75	_thr_umutex_init(&lck->s_lock);
76	return (0);
77}
78
79int
80_pthread_spin_destroy(pthread_spinlock_t *lock)
81{
82	void *l;
83	int ret;
84
85	if (lock == NULL || *lock == NULL) {
86		ret = EINVAL;
87	} else if (*lock == THR_PSHARED_PTR) {
88		l = __thr_pshared_offpage(lock, 0);
89		if (l != NULL)
90			__thr_pshared_destroy(l);
91		ret = 0;
92	} else {
93		free(*lock);
94		*lock = NULL;
95		ret = 0;
96	}
97	return (ret);
98}
99
100int
101_pthread_spin_trylock(pthread_spinlock_t *lock)
102{
103	struct pthread_spinlock	*lck;
104
105	if (lock == NULL || *lock == NULL)
106		return (EINVAL);
107	lck = *lock == THR_PSHARED_PTR ? __thr_pshared_offpage(lock, 0) : *lock;
108	if (lck == NULL)
109		return (EINVAL);
110	return (THR_UMUTEX_TRYLOCK(_get_curthread(), &lck->s_lock));
111}
112
113int
114_pthread_spin_lock(pthread_spinlock_t *lock)
115{
116	struct pthread *curthread;
117	struct pthread_spinlock	*lck;
118	int count;
119
120	if (lock == NULL)
121		return (EINVAL);
122	lck = *lock == THR_PSHARED_PTR ? __thr_pshared_offpage(lock, 0) : *lock;
123	if (lck == NULL)
124		return (EINVAL);
125
126	curthread = _get_curthread();
127	count = SPIN_COUNT;
128	while (THR_UMUTEX_TRYLOCK(curthread, &lck->s_lock) != 0) {
129		while (lck->s_lock.m_owner) {
130			if (!_thr_is_smp) {
131				_pthread_yield();
132			} else {
133				CPU_SPINWAIT;
134				if (--count <= 0) {
135					count = SPIN_COUNT;
136					_pthread_yield();
137				}
138			}
139		}
140	}
141	return (0);
142}
143
144int
145_pthread_spin_unlock(pthread_spinlock_t *lock)
146{
147	struct pthread_spinlock	*lck;
148
149	if (lock == NULL)
150		return (EINVAL);
151	lck = *lock == THR_PSHARED_PTR ? __thr_pshared_offpage(lock, 0) : *lock;
152	if (lck == NULL)
153		return (EINVAL);
154	return (THR_UMUTEX_UNLOCK(_get_curthread(), &lck->s_lock));
155}
156