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 <errno.h>
34#include <pthread.h>
35#include "un-namespace.h"
36#include "thr_private.h"
37
38__weak_reference(_pthread_join, pthread_join);
39
40int
41_pthread_join(pthread_t pthread, void **thread_return)
42{
43	struct pthread *curthread = _get_curthread();
44	void *tmp;
45	kse_critical_t crit;
46	int ret = 0;
47
48	_thr_cancel_enter(curthread);
49
50	/* Check if the caller has specified an invalid thread: */
51	if (pthread == NULL || pthread->magic != THR_MAGIC) {
52		/* Invalid thread: */
53		_thr_cancel_leave(curthread, 1);
54		return (EINVAL);
55	}
56
57	/* Check if the caller has specified itself: */
58	if (pthread == curthread) {
59		/* Avoid a deadlock condition: */
60		_thr_cancel_leave(curthread, 1);
61		return (EDEADLK);
62	}
63
64	/*
65	 * Find the thread in the list of active threads or in the
66	 * list of dead threads:
67	 */
68	if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/1)) != 0) {
69		/* Return an error: */
70		_thr_cancel_leave(curthread, 1);
71		return (ESRCH);
72	}
73
74	THR_SCHED_LOCK(curthread, pthread);
75	/* Check if this thread has been detached: */
76	if ((pthread->attr.flags & PTHREAD_DETACHED) != 0) {
77		THR_SCHED_UNLOCK(curthread, pthread);
78		/* Remove the reference and return an error: */
79		_thr_ref_delete(curthread, pthread);
80		ret = EINVAL;
81	} else {
82		/* Lock the target thread while checking its state. */
83		if (pthread->state == PS_DEAD) {
84			/* Return the thread's return value: */
85			tmp = pthread->ret;
86
87			/* Detach the thread. */
88			pthread->attr.flags |= PTHREAD_DETACHED;
89
90			/* Unlock the thread. */
91			THR_SCHED_UNLOCK(curthread, pthread);
92
93			/*
94			 * Remove the thread from the list of active
95			 * threads and add it to the GC list.
96			 */
97			crit = _kse_critical_enter();
98			KSE_LOCK_ACQUIRE(curthread->kse, &_thread_list_lock);
99			THR_LIST_REMOVE(pthread);
100			THR_GCLIST_ADD(pthread);
101			KSE_LOCK_RELEASE(curthread->kse, &_thread_list_lock);
102			_kse_critical_leave(crit);
103
104			/* Remove the reference. */
105			_thr_ref_delete(curthread, pthread);
106			if (thread_return != NULL)
107				*thread_return = tmp;
108		}
109		else if (pthread->joiner != NULL) {
110			/* Unlock the thread and remove the reference. */
111			THR_SCHED_UNLOCK(curthread, pthread);
112			_thr_ref_delete(curthread, pthread);
113
114			/* Multiple joiners are not supported. */
115			ret = ENOTSUP;
116		}
117		else {
118			/* Set the running thread to be the joiner: */
119			pthread->joiner = curthread;
120
121			/* Keep track of which thread we're joining to: */
122			curthread->join_status.thread = pthread;
123
124			/* Unlock the thread and remove the reference. */
125			THR_SCHED_UNLOCK(curthread, pthread);
126			_thr_ref_delete(curthread, pthread);
127
128			THR_SCHED_LOCK(curthread, curthread);
129			while (curthread->join_status.thread == pthread) {
130				THR_SET_STATE(curthread, PS_JOIN);
131				THR_SCHED_UNLOCK(curthread, curthread);
132				/* Schedule the next thread: */
133				_thr_sched_switch(curthread);
134				THR_SCHED_LOCK(curthread, curthread);
135			}
136			THR_SCHED_UNLOCK(curthread, curthread);
137
138			if ((curthread->cancelflags & THR_CANCELLING) &&
139			   !(curthread->cancelflags & PTHREAD_CANCEL_DISABLE)) {
140				if (_thr_ref_add(curthread, pthread, 1) == 0) {
141					THR_SCHED_LOCK(curthread, pthread);
142					pthread->joiner = NULL;
143					THR_SCHED_UNLOCK(curthread, pthread);
144					_thr_ref_delete(curthread, pthread);
145				}
146				_pthread_exit(PTHREAD_CANCELED);
147			}
148
149			/*
150			 * The thread return value and error are set by the
151			 * thread we're joining to when it exits or detaches:
152			 */
153			ret = curthread->join_status.error;
154			if ((ret == 0) && (thread_return != NULL))
155				*thread_return = curthread->join_status.ret;
156		}
157	}
158	_thr_cancel_leave(curthread, 1);
159
160	/* Return the completion status: */
161	return (ret);
162}
163