2 * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
32 #include "namespace.h"
34 #include "un-namespace.h"
35 #include "thr_private.h"
37 LT10_COMPAT_PRIVATE(_pthread_once);
38 LT10_COMPAT_DEFAULT(pthread_once);
40 __weak_reference(_pthread_once, pthread_once);
42 #define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT
43 #define ONCE_DONE PTHREAD_DONE_INIT
44 #define ONCE_IN_PROGRESS 0x02
45 #define ONCE_MASK 0x03
47 static pthread_mutex_t once_lock = PTHREAD_MUTEX_INITIALIZER;
48 static pthread_cond_t once_cv = PTHREAD_COND_INITIALIZER;
52 * The pthread_once() function is not a cancellation point. However,
53 * if init_routine is a cancellation point and is canceled, the effect
54 * on once_control shall be as if pthread_once() was never called.
58 once_cancel_handler(void *arg)
60 pthread_once_t *once_control = arg;
62 _pthread_mutex_lock(&once_lock);
63 once_control->state = ONCE_NEVER_DONE;
64 _pthread_mutex_unlock(&once_lock);
65 _pthread_cond_broadcast(&once_cv);
69 _pthread_once(pthread_once_t *once_control, void (*init_routine) (void))
71 struct pthread *curthread;
74 if (once_control->state == ONCE_DONE)
76 _pthread_mutex_lock(&once_lock);
77 while (*(volatile int *)&(once_control->state) == ONCE_IN_PROGRESS)
78 _pthread_cond_wait(&once_cv, &once_lock);
80 * If previous thread was canceled, then the state still
81 * could be ONCE_NEVER_DONE, we need to check it again.
83 if (*(volatile int *)&(once_control->state) == ONCE_NEVER_DONE) {
84 once_control->state = ONCE_IN_PROGRESS;
85 _pthread_mutex_unlock(&once_lock);
86 curthread = _get_curthread();
87 THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control);
89 THR_CLEANUP_POP(curthread, 0);
90 _pthread_mutex_lock(&once_lock);
91 once_control->state = ONCE_DONE;
94 _pthread_mutex_unlock(&once_lock);
96 _pthread_cond_broadcast(&once_cv);