xref: /freebsd/lib/libthr/thread/thr_join.c (revision 3416500aef140042c64bc149cb1ec6620483bc44)
1 /*
2  * Copyright (c) 2005, David Xu <davidxu@freebsd.org>
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 unmodified, this list of conditions, and the following
10  *    disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include "namespace.h"
31 #include <errno.h>
32 #include <pthread.h>
33 #include "un-namespace.h"
34 
35 #include "thr_private.h"
36 
37 int	_pthread_timedjoin_np(pthread_t pthread, void **thread_return,
38 	const struct timespec *abstime);
39 static int join_common(pthread_t, void **, const struct timespec *);
40 
41 __weak_reference(_pthread_join, pthread_join);
42 __weak_reference(_pthread_timedjoin_np, pthread_timedjoin_np);
43 
44 static void backout_join(void *arg)
45 {
46 	struct pthread *pthread = (struct pthread *)arg;
47 	struct pthread *curthread = _get_curthread();
48 
49 	THR_THREAD_LOCK(curthread, pthread);
50 	pthread->joiner = NULL;
51 	THR_THREAD_UNLOCK(curthread, pthread);
52 }
53 
54 int
55 _pthread_join(pthread_t pthread, void **thread_return)
56 {
57 	return (join_common(pthread, thread_return, NULL));
58 }
59 
60 int
61 _pthread_timedjoin_np(pthread_t pthread, void **thread_return,
62 	const struct timespec *abstime)
63 {
64 	if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
65 	    abstime->tv_nsec >= 1000000000)
66 		return (EINVAL);
67 
68 	return (join_common(pthread, thread_return, abstime));
69 }
70 
71 /*
72  * Cancellation behavior:
73  *   if the thread is canceled, joinee is not recycled.
74  */
75 static int
76 join_common(pthread_t pthread, void **thread_return,
77 	const struct timespec *abstime)
78 {
79 	struct pthread *curthread = _get_curthread();
80 	struct timespec ts, ts2, *tsp;
81 	void *tmp;
82 	long tid;
83 	int ret = 0;
84 
85 	if (pthread == NULL)
86 		return (EINVAL);
87 
88 	if (pthread == curthread)
89 		return (EDEADLK);
90 
91 	if ((ret = _thr_find_thread(curthread, pthread, 1)) != 0)
92 		return (ESRCH);
93 
94 	if ((pthread->flags & THR_FLAGS_DETACHED) != 0) {
95 		ret = EINVAL;
96 	} else if (pthread->joiner != NULL) {
97 		/* Multiple joiners are not supported. */
98 		ret = ENOTSUP;
99 	}
100 	if (ret) {
101 		THR_THREAD_UNLOCK(curthread, pthread);
102 		return (ret);
103 	}
104 	/* Set the running thread to be the joiner: */
105 	pthread->joiner = curthread;
106 
107 	THR_THREAD_UNLOCK(curthread, pthread);
108 
109 	THR_CLEANUP_PUSH(curthread, backout_join, pthread);
110 	_thr_cancel_enter(curthread);
111 
112 	tid = pthread->tid;
113 	while (pthread->tid != TID_TERMINATED) {
114 		_thr_testcancel(curthread);
115 		if (abstime != NULL) {
116 			clock_gettime(CLOCK_REALTIME, &ts);
117 			TIMESPEC_SUB(&ts2, abstime, &ts);
118 			if (ts2.tv_sec < 0) {
119 				ret = ETIMEDOUT;
120 				break;
121 			}
122 			tsp = &ts2;
123 		} else
124 			tsp = NULL;
125 		ret = _thr_umtx_wait(&pthread->tid, tid, tsp);
126 		if (ret == ETIMEDOUT)
127 			break;
128 	}
129 
130 	_thr_cancel_leave(curthread, 0);
131 	THR_CLEANUP_POP(curthread, 0);
132 
133 	if (ret == ETIMEDOUT) {
134 		THR_THREAD_LOCK(curthread, pthread);
135 		pthread->joiner = NULL;
136 		THR_THREAD_UNLOCK(curthread, pthread);
137 	} else {
138 		ret = 0;
139 		tmp = pthread->ret;
140 		THR_THREAD_LOCK(curthread, pthread);
141 		pthread->flags |= THR_FLAGS_DETACHED;
142 		pthread->joiner = NULL;
143 		_thr_try_gc(curthread, pthread); /* thread lock released */
144 
145 		if (thread_return != NULL)
146 			*thread_return = tmp;
147 	}
148 	return (ret);
149 }
150