1 /* $OpenBSD: uthread_spinlock.c,v 1.13 2003/01/31 04:46:17 marc Exp $ */
2 /*
3 * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 * must display the following acknowledgement:
16 * This product includes software developed by John Birrell.
17 * 4. Neither the name of the author nor the names of any co-contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $FreeBSD: uthread_spinlock.c,v 1.7 1999/08/28 00:03:52 peter Exp $
34 *
35 */
36
37 #include <stdio.h>
38 #include <sched.h>
39 #include <unistd.h>
40 #include <pthread.h>
41 #include <string.h>
42 #include "pthread_private.h"
43
44 extern char *__progname;
45
46 /*
47 * Lock a location for the running thread. Yield to allow other
48 * threads to run if this thread is blocked because the lock is
49 * not available.
50 */
51 void
_spinlock(spinlock_t * lck)52 _spinlock(spinlock_t *lck)
53 {
54 struct pthread *curthread = _get_curthread();
55
56 /*
57 * Try to grab the lock and loop if another thread grabs
58 * it before we do.
59 */
60 while(_atomic_lock(&lck->access_lock)) {
61 /* Block the thread until the lock. */
62 curthread->data.spinlock = lck;
63 _thread_kern_sched_state(PS_SPINBLOCK, __FILE__, __LINE__);
64 }
65
66 /* The running thread now owns the lock: */
67 lck->lock_owner = curthread;
68 }
69
70 /*
71 * Lock a location for the running thread. Yield to allow other
72 * threads to run if this thread is blocked because the lock is
73 * not available. Note that this function does not sleep. It
74 * assumes that the lock will be available very soon.
75 *
76 * This function checks if the running thread has already locked the
77 * location, warns if this occurs and creates a thread dump before
78 * returning.
79 */
80 void
_spinlock_debug(spinlock_t * lck,const char * fname,int lineno)81 _spinlock_debug(spinlock_t *lck, const char *fname, int lineno)
82 {
83 struct pthread *curthread = _get_curthread();
84 int cnt = 0;
85
86 /*
87 * Try to grab the lock and loop if another thread grabs
88 * it before we do.
89 */
90 while(_atomic_lock(&lck->access_lock)) {
91 cnt++;
92 if (cnt > 100) {
93 char str[256];
94 snprintf(str, sizeof(str), "%s - Warning: Thread %p attempted to lock %p from %s (%d) was left locked from %s (%d)\n", __progname, curthread, lck, fname, lineno, lck->fname, lck->lineno);
95 _thread_sys_write(2,str,strlen(str));
96 sleep(1);
97 cnt = 0;
98 }
99
100 /* Block the thread until the lock. */
101 curthread->data.spinlock = lck;
102 _thread_kern_sched_state(PS_SPINBLOCK, fname, lineno);
103 }
104
105 /* The running thread now owns the lock: */
106 lck->lock_owner = curthread;
107 lck->fname = fname;
108 lck->lineno = lineno;
109 }
110