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/types.h>
33 #include <pthread.h>
34 #include <libc_private.h>
35 #include <spinlock.h>
36
37 #include "thr_private.h"
38
39 #define MAX_SPINLOCKS 72
40
41 /*
42 * These data structures are used to trace all spinlocks
43 * in libc.
44 */
45 struct spinlock_extra {
46 spinlock_t *owner;
47 struct umutex lock;
48 };
49
50 static struct umutex spinlock_static_lock = DEFAULT_UMUTEX;
51 static struct spinlock_extra extra[MAX_SPINLOCKS];
52 static int spinlock_count;
53 static int initialized;
54
55 static void init_spinlock(spinlock_t *lck);
56
57 /*
58 * These are for compatibility only. Spinlocks of this type
59 * are deprecated.
60 */
61
62 void
__thr_spinunlock(spinlock_t * lck)63 __thr_spinunlock(spinlock_t *lck)
64 {
65 struct spinlock_extra *_extra;
66
67 _extra = lck->thr_extra;
68 THR_UMUTEX_UNLOCK(_get_curthread(), &_extra->lock);
69 }
70
71 void
__thr_spinlock(spinlock_t * lck)72 __thr_spinlock(spinlock_t *lck)
73 {
74 struct spinlock_extra *_extra;
75
76 if (!_thr_isthreaded())
77 PANIC("Spinlock called when not threaded.");
78 if (!initialized)
79 PANIC("Spinlocks not initialized.");
80 if (lck->thr_extra == NULL)
81 init_spinlock(lck);
82 _extra = lck->thr_extra;
83 THR_UMUTEX_LOCK(_get_curthread(), &_extra->lock);
84 }
85
86 static void
init_spinlock(spinlock_t * lck)87 init_spinlock(spinlock_t *lck)
88 {
89 struct pthread *curthread = _get_curthread();
90
91 THR_UMUTEX_LOCK(curthread, &spinlock_static_lock);
92 if ((lck->thr_extra == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
93 lck->thr_extra = &extra[spinlock_count];
94 _thr_umutex_init(&extra[spinlock_count].lock);
95 extra[spinlock_count].owner = lck;
96 spinlock_count++;
97 }
98 THR_UMUTEX_UNLOCK(curthread, &spinlock_static_lock);
99 if (lck->thr_extra == NULL)
100 PANIC("Warning: exceeded max spinlocks");
101 }
102
103 void
_thr_spinlock_init(void)104 _thr_spinlock_init(void)
105 {
106 int i;
107
108 _thr_umutex_init(&spinlock_static_lock);
109 if (initialized != 0) {
110 /*
111 * called after fork() to reset state of libc spin locks,
112 * it is not quite right since libc may be in inconsistent
113 * state, resetting the locks to allow current thread to be
114 * able to hold them may not help things too much, but
115 * anyway, we do our best.
116 * it is better to do pthread_atfork in libc.
117 */
118 for (i = 0; i < spinlock_count; i++)
119 _thr_umutex_init(&extra[i].lock);
120 } else {
121 initialized = 1;
122 }
123 }
124