thr_join.c revision 114187 
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 114187 2003-04-28 23:56:12Z deischen $
33 */
34#include <errno.h>
35#include <pthread.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	kse_critical_t crit;
45	int ret = 0;
46
47	_thr_enter_cancellation_point(curthread);
48
49	/* Check if the caller has specified an invalid thread: */
50	if (pthread == NULL || pthread->magic != THR_MAGIC) {
51		/* Invalid thread: */
52		_thr_leave_cancellation_point(curthread);
53		return (EINVAL);
54	}
55
56	/* Check if the caller has specified itself: */
57	if (pthread == curthread) {
58		/* Avoid a deadlock condition: */
59		_thr_leave_cancellation_point(curthread);
60		return (EDEADLK);
61	}
62
63	/*
64	 * Find the thread in the list of active threads or in the
65	 * list of dead threads:
66	 */
67	if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/1)) != 0) {
68		/* Return an error: */
69		_thr_leave_cancellation_point(curthread);
70		return (ESRCH);
71	}
72
73	THR_SCHED_LOCK(curthread, pthread);
74	/* Check if this thread has been detached: */
75	if ((pthread->attr.flags & PTHREAD_DETACHED) != 0) {
76		THR_SCHED_UNLOCK(curthread, pthread);
77		/* Remove the reference and return an error: */
78		_thr_ref_delete(curthread, pthread);
79		ret = ESRCH;
80	} else {
81		/* Lock the target thread while checking its state. */
82		if (pthread->state == PS_DEAD) {
83			if (thread_return != NULL)
84				/* Return the thread's return value: */
85				*thread_return = 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		}
107		else if (pthread->joiner != NULL) {
108			/* Unlock the thread and remove the reference. */
109			THR_SCHED_UNLOCK(curthread, pthread);
110			_thr_ref_delete(curthread, pthread);
111
112			/* Multiple joiners are not supported. */
113			ret = ENOTSUP;
114		}
115		else {
116			/* Set the running thread to be the joiner: */
117			pthread->joiner = curthread;
118
119			/* Keep track of which thread we're joining to: */
120			curthread->join_status.thread = pthread;
121
122			/* Unlock the thread and remove the reference. */
123			THR_SCHED_UNLOCK(curthread, pthread);
124			_thr_ref_delete(curthread, pthread);
125
126			THR_LOCK_SWITCH(curthread);
127			while (curthread->join_status.thread == pthread) {
128				THR_SET_STATE(curthread, PS_JOIN);
129				/* Schedule the next thread: */
130				_thr_sched_switch(curthread);
131			}
132			THR_UNLOCK_SWITCH(curthread);
133
134			/*
135			 * The thread return value and error are set by the
136			 * thread we're joining to when it exits or detaches:
137			 */
138			ret = curthread->join_status.error;
139			if ((ret == 0) && (thread_return != NULL))
140				*thread_return = curthread->join_status.ret;
141		}
142	}
143	_thr_leave_cancellation_point(curthread);
144
145	/* Return the completion status: */
146	return (ret);
147}
148