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: stable/9/lib/libthr/thread/thr_spinlock.c 178446 2008-04-23 21:06:51Z delphij $
30 *
31 */
32
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 compatability only. Spinlocks of this type
60 * are deprecated.
61 */
62
63 void
_spinunlock(spinlock_t * lck)64 _spinunlock(spinlock_t *lck)
65 {
66 struct spinlock_extra *_extra;
67
68 _extra = (struct spinlock_extra *)lck->fname;
69 THR_UMUTEX_UNLOCK(_get_curthread(), &_extra->lock);
70 }
71
72 void
_spinlock(spinlock_t * lck)73 _spinlock(spinlock_t *lck)
74 {
75 struct spinlock_extra *_extra;
76
77 if (!__isthreaded)
78 PANIC("Spinlock called when not threaded.");
79 if (!initialized)
80 PANIC("Spinlocks not initialized.");
81 if (lck->fname == NULL)
82 init_spinlock(lck);
83 _extra = (struct spinlock_extra *)lck->fname;
84 THR_UMUTEX_LOCK(_get_curthread(), &_extra->lock);
85 }
86
87 void
_spinlock_debug(spinlock_t * lck,char * fname __unused,int lineno __unused)88 _spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused)
89 {
90 _spinlock(lck);
91 }
92
93 static void
init_spinlock(spinlock_t * lck)94 init_spinlock(spinlock_t *lck)
95 {
96 struct pthread *curthread = _get_curthread();
97
98 THR_UMUTEX_LOCK(curthread, &spinlock_static_lock);
99 if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
100 lck->fname = (char *)&extra[spinlock_count];
101 _thr_umutex_init(&extra[spinlock_count].lock);
102 extra[spinlock_count].owner = lck;
103 spinlock_count++;
104 }
105 THR_UMUTEX_UNLOCK(curthread, &spinlock_static_lock);
106 if (lck->fname == NULL)
107 PANIC("Warning: exceeded max spinlocks");
108 }
109
110 void
_thr_spinlock_init(void)111 _thr_spinlock_init(void)
112 {
113 int i;
114
115 _thr_umutex_init(&spinlock_static_lock);
116 if (initialized != 0) {
117 /*
118 * called after fork() to reset state of libc spin locks,
119 * it is not quite right since libc may be in inconsistent
120 * state, resetting the locks to allow current thread to be
121 * able to hold them may not help things too much, but
122 * anyway, we do our best.
123 * it is better to do pthread_atfork in libc.
124 */
125 for (i = 0; i < spinlock_count; i++)
126 _thr_umutex_init(&extra[i].lock);
127 } else {
128 initialized = 1;
129 }
130 }
131