thr_join.c revision 68516 
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. 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_join.c 68516 2000-11-09 05:08:26Z deischen $
33 */
34#include <errno.h>
35#ifdef _THREAD_SAFE
36#include <pthread.h>
37#include "pthread_private.h"
38
39int
40pthread_join(pthread_t pthread, void **thread_return)
41{
42	int ret = 0;
43
44	_thread_enter_cancellation_point();
45
46	/* Check if the caller has specified an invalid thread: */
47	if (pthread == NULL || pthread->magic != PTHREAD_MAGIC) {
48		/* Invalid thread: */
49		_thread_leave_cancellation_point();
50		return(EINVAL);
51	}
52
53	/* Check if the caller has specified itself: */
54	if (pthread == _thread_run) {
55		/* Avoid a deadlock condition: */
56		_thread_leave_cancellation_point();
57		return(EDEADLK);
58	}
59
60	/*
61	 * Find the thread in the list of active threads or in the
62	 * list of dead threads:
63	 */
64	if ((_find_thread(pthread) != 0) && (_find_dead_thread(pthread) != 0))
65		/* Return an error: */
66		ret = ESRCH;
67
68	/* Check if this thread has been detached: */
69	else if ((pthread->attr.flags & PTHREAD_DETACHED) != 0)
70		/* Return an error: */
71		ret = ESRCH;
72
73	/* Check if the thread is not dead: */
74	else if (pthread->state != PS_DEAD) {
75		PTHREAD_ASSERT_NOT_IN_SYNCQ(_thread_run);
76
77		/*
78		 * Enter a loop in case this thread is woken prematurely
79		 * in order to invoke a signal handler:
80		 */
81		for (;;) {
82			/* Clear the interrupted flag: */
83			_thread_run->interrupted = 0;
84
85			/*
86			 * Protect against being context switched out while
87			 * adding this thread to the join queue.
88			 */
89			_thread_kern_sig_defer();
90
91			/* Add the running thread to the join queue: */
92			TAILQ_INSERT_TAIL(&(pthread->join_queue),
93			    _thread_run, sqe);
94			_thread_run->flags |= PTHREAD_FLAGS_IN_JOINQ;
95			_thread_run->data.thread = pthread;
96
97			/* Schedule the next thread: */
98			_thread_kern_sched_state(PS_JOIN, __FILE__, __LINE__);
99
100			if ((_thread_run->flags & PTHREAD_FLAGS_IN_JOINQ) != 0) {
101				TAILQ_REMOVE(&(pthread->join_queue),
102				    _thread_run, sqe);
103				_thread_run->flags &= ~PTHREAD_FLAGS_IN_JOINQ;
104			}
105			_thread_run->data.thread = NULL;
106
107			_thread_kern_sig_undefer();
108
109			if (_thread_run->interrupted != 0) {
110				if (_thread_run->continuation != NULL)
111					_thread_run->continuation(_thread_run);
112				/*
113				 * This thread was interrupted, probably to
114				 * invoke a signal handler.  Make sure the
115				 * target thread is still joinable.
116				 */
117				if (((_find_thread(pthread) != 0) &&
118				    (_find_dead_thread(pthread) != 0)) ||
119				    ((pthread->attr.flags &
120				    PTHREAD_DETACHED) != 0)) {
121					/* Return an error: */
122					ret = ESRCH;
123
124					/* We're done; break out of the loop. */
125					break;
126				}
127				else if (pthread->state == PS_DEAD) {
128					/* We're done; break out of the loop. */
129					break;
130				}
131			} else {
132				/*
133				 * The thread return value and error are set
134				 * by the thread we're joining to when it
135				 * exits or detaches:
136				 */
137				ret = _thread_run->error;
138				if ((ret == 0) && (thread_return != NULL))
139					*thread_return = _thread_run->ret;
140
141				/* We're done; break out of the loop. */
142				break;
143			}
144		}
145	/* Check if the return value is required: */
146	} else if (thread_return != NULL)
147		/* Return the thread's return value: */
148		*thread_return = pthread->ret;
149
150	_thread_leave_cancellation_point();
151
152	/* Return the completion status: */
153	return (ret);
154}
155
156void
157_join_backout(pthread_t pthread)
158{
159	_thread_kern_sig_defer();
160	if ((pthread->flags & PTHREAD_FLAGS_IN_JOINQ) != 0) {
161		TAILQ_REMOVE(&pthread->data.thread->join_queue, pthread, sqe);
162		_thread_run->flags &= ~PTHREAD_FLAGS_IN_JOINQ;
163	}
164	_thread_kern_sig_undefer();
165}
166#endif
167