thr_spinlock.c revision 71581 
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. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by John Birrell.
16 * 4. Neither the name of the author nor the names of any co-contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $FreeBSD: head/lib/libkse/thread/thr_spinlock.c 71581 2001-01-24 13:03:38Z deischen $
33 *
34 */
35
36#include <stdio.h>
37#include <sched.h>
38#include <unistd.h>
39#include <pthread.h>
40#include <string.h>
41#include "pthread_private.h"
42
43extern char *__progname;
44
45/*
46 * Lock a location for the running thread. Yield to allow other
47 * threads to run if this thread is blocked because the lock is
48 * not available. Note that this function does not sleep. It
49 * assumes that the lock will be available very soon.
50 */
51void
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 = (long) 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 */
80void
81_spinlock_debug(spinlock_t *lck, 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			__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 = (long) curthread;
107	lck->fname = fname;
108	lck->lineno = lineno;
109}
110