1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the author nor the names of any co-contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD$");
34
35#include <sys/types.h>
36#include <pthread.h>
37#include <libc_private.h>
38#include <spinlock.h>
39
40#include "thr_private.h"
41
42#define	MAX_SPINLOCKS	72
43
44/*
45 * These data structures are used to trace all spinlocks
46 * in libc.
47 */
48struct spinlock_extra {
49	spinlock_t	*owner;
50	struct umutex	lock;
51};
52
53static struct umutex		spinlock_static_lock = DEFAULT_UMUTEX;
54static struct spinlock_extra	extra[MAX_SPINLOCKS];
55static int			spinlock_count;
56static int			initialized;
57
58static void	init_spinlock(spinlock_t *lck);
59
60/*
61 * These are for compatibility only.  Spinlocks of this type
62 * are deprecated.
63 */
64
65void
66__thr_spinunlock(spinlock_t *lck)
67{
68	struct spinlock_extra	*_extra;
69
70	_extra = lck->thr_extra;
71	THR_UMUTEX_UNLOCK(_get_curthread(), &_extra->lock);
72}
73
74void
75__thr_spinlock(spinlock_t *lck)
76{
77	struct spinlock_extra *_extra;
78
79	if (!_thr_isthreaded())
80		PANIC("Spinlock called when not threaded.");
81	if (!initialized)
82		PANIC("Spinlocks not initialized.");
83	if (lck->thr_extra == NULL)
84		init_spinlock(lck);
85	_extra = lck->thr_extra;
86	THR_UMUTEX_LOCK(_get_curthread(), &_extra->lock);
87}
88
89static void
90init_spinlock(spinlock_t *lck)
91{
92	struct pthread *curthread = _get_curthread();
93
94	THR_UMUTEX_LOCK(curthread, &spinlock_static_lock);
95	if ((lck->thr_extra == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
96		lck->thr_extra = &extra[spinlock_count];
97		_thr_umutex_init(&extra[spinlock_count].lock);
98		extra[spinlock_count].owner = lck;
99		spinlock_count++;
100	}
101	THR_UMUTEX_UNLOCK(curthread, &spinlock_static_lock);
102	if (lck->thr_extra == NULL)
103		PANIC("Warning: exceeded max spinlocks");
104}
105
106void
107_thr_spinlock_init(void)
108{
109	int i;
110
111	_thr_umutex_init(&spinlock_static_lock);
112	if (initialized != 0) {
113		/*
114		 * called after fork() to reset state of libc spin locks,
115		 * it is not quite right since libc may be in inconsistent
116		 * state, resetting the locks to allow current thread to be
117		 * able to hold them may not help things too much, but
118		 * anyway, we do our best.
119		 * it is better to do pthread_atfork in libc.
120		 */
121		for (i = 0; i < spinlock_count; i++)
122			_thr_umutex_init(&extra[i].lock);
123	} else {
124		initialized = 1;
125	}
126}
127