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. 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.
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
32 * $FreeBSD: src/lib/libc_r/uthread/uthread_join.c,v 1.12.2.8 2002/10/22 14:44:03 fjoe Exp $
36 #include "pthread_private.h"
38 __weak_reference(_pthread_join, pthread_join);
41 _pthread_join(pthread_t pthread, void **thread_return)
43 struct pthread *curthread = _get_curthread();
47 _thread_enter_cancellation_point();
49 /* Check if the caller has specified an invalid thread: */
50 if (pthread == NULL || pthread->magic != PTHREAD_MAGIC) {
52 _thread_leave_cancellation_point();
56 /* Check if the caller has specified itself: */
57 if (pthread == curthread) {
58 /* Avoid a deadlock condition: */
59 _thread_leave_cancellation_point();
64 * Lock the garbage collector mutex to ensure that the garbage
65 * collector is not using the dead thread list.
67 if (pthread_mutex_lock(&_gc_mutex) != 0)
68 PANIC("Cannot lock gc mutex");
71 * Defer signals to protect the thread list from access
72 * by the signal handler:
74 _thread_kern_sig_defer();
77 * Unlock the garbage collector mutex, now that the garbage collector
80 if (pthread_mutex_unlock(&_gc_mutex) != 0)
81 PANIC("Cannot lock gc mutex");
84 * Search for the specified thread in the list of active threads. This
85 * is done manually here rather than calling _find_thread() because
86 * the searches in _thread_list and _dead_list (as well as setting up
87 * join/detach state) have to be done atomically.
89 TAILQ_FOREACH(thread, &_thread_list, tle) {
90 if (thread == pthread)
95 * Search for the specified thread in the list of dead threads:
97 TAILQ_FOREACH(thread, &_dead_list, dle) {
98 if (thread == pthread)
103 /* Check if the thread was not found or has been detached: */
104 if (thread == NULL ||
105 ((pthread->attr.flags & PTHREAD_DETACHED) != 0)) {
106 /* Undefer and handle pending signals, yielding if necessary: */
107 _thread_kern_sig_undefer();
109 /* Return an error: */
112 } else if (pthread->joiner != NULL) {
113 /* Undefer and handle pending signals, yielding if necessary: */
114 _thread_kern_sig_undefer();
116 /* Multiple joiners are not supported. */
119 /* Check if the thread is not dead: */
120 } else if (pthread->state != PS_DEAD) {
121 /* Set the running thread to be the joiner: */
122 pthread->joiner = curthread;
124 /* Keep track of which thread we're joining to: */
125 curthread->join_status.thread = pthread;
127 while (curthread->join_status.thread == pthread) {
128 /* Schedule the next thread: */
129 _thread_kern_sched_state(PS_JOIN, __FILE__, __LINE__);
133 * The thread return value and error are set by the thread we're
134 * joining to when it exits or detaches:
136 ret = curthread->join_status.error;
137 if ((ret == 0) && (thread_return != NULL))
138 *thread_return = curthread->join_status.ret;
141 * The thread exited (is dead) without being detached, and no
142 * thread has joined it.
145 /* Check if the return value is required: */
146 if (thread_return != NULL) {
147 /* Return the thread's return value: */
148 *thread_return = pthread->ret;
151 /* Make the thread collectable by the garbage collector. */
152 pthread->attr.flags |= PTHREAD_DETACHED;
154 /* Undefer and handle pending signals, yielding if necessary: */
155 _thread_kern_sig_undefer();
158 _thread_leave_cancellation_point();
160 /* Return the completion status: */