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 * $FreeBSD$
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
68/*
69 * These are for compatability only.  Spinlocks of this type
70 * are deprecated.
71 */
72
73void
74_spinunlock(spinlock_t *lck)
75{
76	struct spinlock_extra *sl_extra;
77
78	sl_extra = ((nv_spinlock_t *)lck)->extra;
79	_pthread_mutex_unlock(&sl_extra->lock);
80}
81
82/*
83 * Lock a location for the running thread. Yield to allow other
84 * threads to run if this thread is blocked because the lock is
85 * not available. Note that this function does not sleep. It
86 * assumes that the lock will be available very soon.
87 */
88void
89_spinlock(spinlock_t *lck)
90{
91	struct spinlock_extra *sl_extra;
92
93	if (!__isthreaded)
94		PANIC("Spinlock called when not threaded.");
95	if (!initialized)
96		PANIC("Spinlocks not initialized.");
97	/*
98	 * Try to grab the lock and loop if another thread grabs
99	 * it before we do.
100	 */
101	if (lck->fname == NULL)
102		init_spinlock(lck);
103	sl_extra = ((nv_spinlock_t *)lck)->extra;
104	_pthread_mutex_lock(&sl_extra->lock);
105}
106
107/*
108 * Lock a location for the running thread. Yield to allow other
109 * threads to run if this thread is blocked because the lock is
110 * not available. Note that this function does not sleep. It
111 * assumes that the lock will be available very soon.
112 *
113 * This function checks if the running thread has already locked the
114 * location, warns if this occurs and creates a thread dump before
115 * returning.
116 */
117void
118_spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused)
119{
120	_spinlock(lck);
121}
122
123static void
124init_spinlock(spinlock_t *lck)
125{
126	_pthread_mutex_lock(&spinlock_static_lock);
127	if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
128		lck->fname = (char *)&extra[spinlock_count];
129		extra[spinlock_count].owner = lck;
130		spinlock_count++;
131	}
132	_pthread_mutex_unlock(&spinlock_static_lock);
133	if (lck->fname == NULL)
134		PANIC("Exceeded max spinlocks");
135}
136
137void
138_thr_spinlock_init(void)
139{
140	int i;
141
142	if (initialized != 0) {
143		_thr_mutex_reinit(&spinlock_static_lock);
144		for (i = 0; i < spinlock_count; i++)
145			_thr_mutex_reinit(&extra[i].lock);
146	} else {
147		if (_pthread_mutex_init(&spinlock_static_lock, &static_mattr))
148			PANIC("Cannot initialize spinlock_static_lock");
149		for (i = 0; i < MAX_SPINLOCKS; i++) {
150			if (_pthread_mutex_init(&extra[i].lock, &static_mattr))
151				PANIC("Cannot initialize spinlock extra");
152		}
153		initialized = 1;
154	}
155}
156