1/*
2 * Copyright (c) 1995 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 * $FreeBSD$
30 */
31
32#include "namespace.h"
33#include <pthread.h>
34#include "un-namespace.h"
35#include "thr_private.h"
36
37__weak_reference(_pthread_once, pthread_once);
38
39#define ONCE_NEVER_DONE		PTHREAD_NEEDS_INIT
40#define ONCE_DONE		PTHREAD_DONE_INIT
41#define	ONCE_IN_PROGRESS	0x02
42#define	ONCE_MASK		0x03
43
44static pthread_mutex_t		once_lock = PTHREAD_MUTEX_INITIALIZER;
45static pthread_cond_t		once_cv = PTHREAD_COND_INITIALIZER;
46
47/*
48 * POSIX:
49 * The pthread_once() function is not a cancellation point. However,
50 * if init_routine is a cancellation point and is canceled, the effect
51 * on once_control shall be as if pthread_once() was never called.
52 */
53
54static void
55once_cancel_handler(void *arg)
56{
57	pthread_once_t *once_control = arg;
58
59	_pthread_mutex_lock(&once_lock);
60	once_control->state = ONCE_NEVER_DONE;
61	_pthread_mutex_unlock(&once_lock);
62	_pthread_cond_broadcast(&once_cv);
63}
64
65int
66_pthread_once(pthread_once_t *once_control, void (*init_routine) (void))
67{
68	struct pthread *curthread;
69	int wakeup = 0;
70
71	if (once_control->state == ONCE_DONE)
72		return (0);
73	_pthread_mutex_lock(&once_lock);
74	while (*(volatile int *)&(once_control->state) == ONCE_IN_PROGRESS)
75		_pthread_cond_wait(&once_cv, &once_lock);
76	/*
77	 * If previous thread was canceled, then the state still
78	 * could be ONCE_NEVER_DONE, we need to check it again.
79	 */
80	if (*(volatile int *)&(once_control->state) == ONCE_NEVER_DONE) {
81		once_control->state = ONCE_IN_PROGRESS;
82		_pthread_mutex_unlock(&once_lock);
83		curthread = _get_curthread();
84		THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control);
85		init_routine();
86		THR_CLEANUP_POP(curthread, 0);
87		_pthread_mutex_lock(&once_lock);
88		once_control->state = ONCE_DONE;
89		wakeup = 1;
90	}
91	_pthread_mutex_unlock(&once_lock);
92	if (wakeup)
93		_pthread_cond_broadcast(&once_cv);
94	return (0);
95}
96
97