thr_spinlock.c revision 174112 
1/*
2 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
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 * 3. Neither the name of the author nor the names of any co-contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: head/lib/libkse/thread/thr_spinlock.c 174112 2007-11-30 17:20:29Z deischen $
30 *
31 */
32
33#include "namespace.h"
34#include <sys/types.h>
35#include <machine/atomic.h>
36#include <pthread.h>
37#include <libc_private.h>
38#include "un-namespace.h"
39#include "spinlock.h"
40#include "thr_private.h"
41
42#define	MAX_SPINLOCKS	72
43
44struct spinlock_extra {
45	spinlock_t	*owner;
46	pthread_mutex_t	lock;
47};
48
49struct nv_spinlock {
50	long   access_lock;
51	long   lock_owner;
52	struct spinlock_extra *extra;	/* overlays fname in spinlock_t */
53	int    lineno;
54};
55typedef struct nv_spinlock nv_spinlock_t;
56
57static void	init_spinlock(spinlock_t *lck);
58
59static struct pthread_mutex_attr static_mutex_attr =
60    PTHREAD_MUTEXATTR_STATIC_INITIALIZER;
61static pthread_mutexattr_t	static_mattr = &static_mutex_attr;
62
63static pthread_mutex_t		spinlock_static_lock;
64static struct spinlock_extra	extra[MAX_SPINLOCKS];
65static int			spinlock_count = 0;
66static int			initialized = 0;
67
68LT10_COMPAT_PRIVATE(_spinlock);
69LT10_COMPAT_PRIVATE(_spinlock_debug);
70LT10_COMPAT_PRIVATE(_spinunlock);
71
72/*
73 * These are for compatability only.  Spinlocks of this type
74 * are deprecated.
75 */
76
77void
78_spinunlock(spinlock_t *lck)
79{
80	struct spinlock_extra *sl_extra;
81
82	sl_extra = ((nv_spinlock_t *)lck)->extra;
83	_pthread_mutex_unlock(&sl_extra->lock);
84}
85
86/*
87 * Lock a location for the running thread. Yield to allow other
88 * threads to run if this thread is blocked because the lock is
89 * not available. Note that this function does not sleep. It
90 * assumes that the lock will be available very soon.
91 */
92void
93_spinlock(spinlock_t *lck)
94{
95	struct spinlock_extra *sl_extra;
96
97	if (!__isthreaded)
98		PANIC("Spinlock called when not threaded.");
99	if (!initialized)
100		PANIC("Spinlocks not initialized.");
101	/*
102	 * Try to grab the lock and loop if another thread grabs
103	 * it before we do.
104	 */
105	if (lck->fname == NULL)
106		init_spinlock(lck);
107	sl_extra = ((nv_spinlock_t *)lck)->extra;
108	_pthread_mutex_lock(&sl_extra->lock);
109}
110
111/*
112 * Lock a location for the running thread. Yield to allow other
113 * threads to run if this thread is blocked because the lock is
114 * not available. Note that this function does not sleep. It
115 * assumes that the lock will be available very soon.
116 *
117 * This function checks if the running thread has already locked the
118 * location, warns if this occurs and creates a thread dump before
119 * returning.
120 */
121void
122_spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused)
123{
124	_spinlock(lck);
125}
126
127static void
128init_spinlock(spinlock_t *lck)
129{
130	_pthread_mutex_lock(&spinlock_static_lock);
131	if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
132		lck->fname = (char *)&extra[spinlock_count];
133		extra[spinlock_count].owner = lck;
134		spinlock_count++;
135	}
136	_pthread_mutex_unlock(&spinlock_static_lock);
137	if (lck->fname == NULL)
138		PANIC("Exceeded max spinlocks");
139}
140
141void
142_thr_spinlock_init(void)
143{
144	int i;
145
146	if (initialized != 0) {
147		_thr_mutex_reinit(&spinlock_static_lock);
148		for (i = 0; i < spinlock_count; i++)
149			_thr_mutex_reinit(&extra[i].lock);
150	} else {
151		if (_pthread_mutex_init(&spinlock_static_lock, &static_mattr))
152			PANIC("Cannot initialize spinlock_static_lock");
153		for (i = 0; i < MAX_SPINLOCKS; i++) {
154			if (_pthread_mutex_init(&extra[i].lock, &static_mattr))
155				PANIC("Cannot initialize spinlock extra");
156		}
157		initialized = 1;
158	}
159}
160