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, 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  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #include "namespace.h"
27 #include <machine/tls.h>
28 #include <errno.h>
29 #include <pthread.h>
30 #include "un-namespace.h"
31 
32 #include "thr_private.h"
33 
34 #define cpu_ccfence()       __asm __volatile("" : : : "memory")
35 
36 int _pthread_timedjoin_np(pthread_t pthread, void **thread_return,
37 	const struct timespec *abstime);
38 
39 static int join_common(pthread_t, void **, const struct timespec *);
40 
41 static void backout_join(void *arg)
42 {
43 	pthread_t curthread = tls_get_curthread();
44 	pthread_t pthread = (pthread_t)arg;
45 
46 	THREAD_LIST_LOCK(curthread);
47 	pthread->joiner = NULL;
48 	THREAD_LIST_UNLOCK(curthread);
49 }
50 
51 int
52 _pthread_join(pthread_t pthread, void **thread_return)
53 {
54 	return (join_common(pthread, thread_return, NULL));
55 }
56 
57 int
58 _pthread_timedjoin_np(pthread_t pthread, void **thread_return,
59 	const struct timespec *abstime)
60 {
61 	if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
62 	    abstime->tv_nsec >= 1000000000)
63 		return (EINVAL);
64 
65 	return (join_common(pthread, thread_return, abstime));
66 }
67 
68 static int
69 join_common(pthread_t pthread, void **thread_return,
70 	const struct timespec *abstime)
71 {
72 	pthread_t curthread = tls_get_curthread();
73 	struct timespec ts, ts2, *tsp;
74 	void *tmp;
75 	long state;
76 	int oldcancel;
77 	int ret = 0;
78 
79 	if (pthread == NULL)
80 		return (EINVAL);
81 
82 	if (pthread == curthread)
83 		return (EDEADLK);
84 
85 	THREAD_LIST_LOCK(curthread);
86 	if ((ret = _thr_find_thread(curthread, pthread, 1)) != 0) {
87 		ret = ESRCH;
88 	} else if ((pthread->tlflags & TLFLAGS_DETACHED) != 0) {
89 		ret = EINVAL;
90 	} else if (pthread->joiner != NULL) {
91 		/* Multiple joiners are not supported. */
92 		ret = ENOTSUP;
93 	}
94 	if (ret) {
95 		THREAD_LIST_UNLOCK(curthread);
96 		return (ret);
97 	}
98 	/* Set the running thread to be the joiner: */
99 	pthread->joiner = curthread;
100 
101 	THREAD_LIST_UNLOCK(curthread);
102 
103 	THR_CLEANUP_PUSH(curthread, backout_join, pthread);
104 	oldcancel = _thr_cancel_enter(curthread);
105 
106 	while ((state = pthread->state) != PS_DEAD) {
107 		cpu_ccfence();
108 		if (abstime != NULL) {
109 			clock_gettime(CLOCK_REALTIME, &ts);
110 			timespecsub(abstime, &ts, &ts2);
111 			if (ts2.tv_sec < 0) {
112 				ret = ETIMEDOUT;
113 				break;
114 			}
115 			tsp = &ts2;
116 		} else
117 			tsp = NULL;
118 		ret = _thr_umtx_wait(&pthread->state, state, tsp,
119 				     CLOCK_REALTIME);
120 		if (ret == ETIMEDOUT)
121 			break;
122 	}
123 
124 	_thr_cancel_leave(curthread, oldcancel);
125 	THR_CLEANUP_POP(curthread, 0);
126 
127 	if (ret == ETIMEDOUT) {
128 		THREAD_LIST_LOCK(curthread);
129 		pthread->joiner = NULL;
130 		THREAD_LIST_UNLOCK(curthread);
131 	} else {
132 		ret = 0;
133 		tmp = pthread->ret;
134 		THREAD_LIST_LOCK(curthread);
135 		pthread->tlflags |= TLFLAGS_DETACHED;
136 		pthread->joiner = NULL;
137 		THR_GCLIST_ADD(pthread);
138 		THREAD_LIST_UNLOCK(curthread);
139 
140 		if (thread_return != NULL)
141 			*thread_return = tmp;
142 	}
143 	return (ret);
144 }
145 
146 __strong_reference(_pthread_join, pthread_join);
147 __strong_reference(_pthread_timedjoin_np, pthread_timedjoin_np);
148