1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1997 John Birrell <[email protected]>.
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 #include <sys/types.h>
34 #include <pthread.h>
35 #include <libc_private.h>
36 #include <spinlock.h>
37
38 #include "thr_private.h"
39
40 #define MAX_SPINLOCKS 72
41
42 /*
43 * These data structures are used to trace all spinlocks
44 * in libc.
45 */
46 struct spinlock_extra {
47 spinlock_t *owner;
48 struct umutex lock;
49 };
50
51 static struct umutex spinlock_static_lock = DEFAULT_UMUTEX;
52 static struct spinlock_extra extra[MAX_SPINLOCKS];
53 static int spinlock_count;
54 static int initialized;
55
56 static void init_spinlock(spinlock_t *lck);
57
58 /*
59 * These are for compatibility only. Spinlocks of this type
60 * are deprecated.
61 */
62
63 void
__thr_spinunlock(spinlock_t * lck)64 __thr_spinunlock(spinlock_t *lck)
65 {
66 struct spinlock_extra *_extra;
67
68 _extra = lck->thr_extra;
69 THR_UMUTEX_UNLOCK(_get_curthread(), &_extra->lock);
70 }
71
72 void
__thr_spinlock(spinlock_t * lck)73 __thr_spinlock(spinlock_t *lck)
74 {
75 struct spinlock_extra *_extra;
76
77 if (!_thr_isthreaded())
78 PANIC("Spinlock called when not threaded.");
79 if (!initialized)
80 PANIC("Spinlocks not initialized.");
81 if (lck->thr_extra == NULL)
82 init_spinlock(lck);
83 _extra = lck->thr_extra;
84 THR_UMUTEX_LOCK(_get_curthread(), &_extra->lock);
85 }
86
87 static void
init_spinlock(spinlock_t * lck)88 init_spinlock(spinlock_t *lck)
89 {
90 struct pthread *curthread = _get_curthread();
91
92 THR_UMUTEX_LOCK(curthread, &spinlock_static_lock);
93 if ((lck->thr_extra == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
94 lck->thr_extra = &extra[spinlock_count];
95 _thr_umutex_init(&extra[spinlock_count].lock);
96 extra[spinlock_count].owner = lck;
97 spinlock_count++;
98 }
99 THR_UMUTEX_UNLOCK(curthread, &spinlock_static_lock);
100 if (lck->thr_extra == NULL)
101 PANIC("Warning: exceeded max spinlocks");
102 }
103
104 void
_thr_spinlock_init(void)105 _thr_spinlock_init(void)
106 {
107 int i;
108
109 _thr_umutex_init(&spinlock_static_lock);
110 if (initialized != 0) {
111 /*
112 * called after fork() to reset state of libc spin locks,
113 * it is not quite right since libc may be in inconsistent
114 * state, resetting the locks to allow current thread to be
115 * able to hold them may not help things too much, but
116 * anyway, we do our best.
117 * it is better to do pthread_atfork in libc.
118 */
119 for (i = 0; i < spinlock_count; i++)
120 _thr_umutex_init(&extra[i].lock);
121 } else {
122 initialized = 1;
123 }
124 }
125