Make thread suspension really work.
[dragonfly.git] / lib / libthread_xu / thread / thr_suspend_np.c
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1/*
2 * Copyright (c) 1995-1998 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: src/lib/libpthread/thread/thr_suspend_np.c,v 1.19 2003/05/04 16:17:01 deischen Exp $
fd4288bd 33 * $DragonFly: src/lib/libthread_xu/thread/thr_suspend_np.c,v 1.3 2006/03/19 13:07:12 davidxu Exp $
71b3fa15 34 */
9e2ee207 35
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36#include <errno.h>
37#include <pthread.h>
fd4288bd 38
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39#include "thr_private.h"
40
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41static int suspend_common(struct pthread *, struct pthread *,
42 int);
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43
44__weak_reference(_pthread_suspend_np, pthread_suspend_np);
45__weak_reference(_pthread_suspend_all_np, pthread_suspend_all_np);
46
47/* Suspend a thread: */
48int
49_pthread_suspend_np(pthread_t thread)
50{
9e2ee207 51 struct pthread *curthread = tls_get_curthread();
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52 int ret;
53
54 /* Suspending the current thread doesn't make sense. */
9e2ee207 55 if (thread == curthread)
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56 ret = EDEADLK;
57
58 /* Add a reference to the thread: */
59 else if ((ret = _thr_ref_add(curthread, thread, /*include dead*/0))
60 == 0) {
61 /* Lock the threads scheduling queue: */
62 THR_THREAD_LOCK(curthread, thread);
fd4288bd 63 suspend_common(curthread, thread, 1);
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64 /* Unlock the threads scheduling queue: */
65 THR_THREAD_UNLOCK(curthread, thread);
66
67 /* Don't forget to remove the reference: */
68 _thr_ref_delete(curthread, thread);
69 }
70 return (ret);
71}
72
73void
74_pthread_suspend_all_np(void)
75{
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76 struct pthread *curthread = tls_get_curthread();
77 struct pthread *thread;
78 int ret;
71b3fa15 79
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80 THREAD_LIST_LOCK(curthread);
81
82 TAILQ_FOREACH(thread, &_thread_list, tle) {
83 if (thread != curthread) {
84 THR_THREAD_LOCK(curthread, thread);
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85 if (thread->state != PS_DEAD &&
86 !(thread->flags & THR_FLAGS_SUSPENDED))
87 thread->flags |= THR_FLAGS_NEED_SUSPEND;
88 THR_THREAD_UNLOCK(curthread, thread);
89 }
90 }
91 /* thr_kill(-1, SIGCANCEL); */
92
93restart:
94 TAILQ_FOREACH(thread, &_thread_list, tle) {
95 if (thread != curthread) {
96 /* First try to suspend the thread without waiting */
97 THR_THREAD_LOCK(curthread, thread);
98 ret = suspend_common(curthread, thread, 0);
99 if (ret == 0) {
100 /* Can not suspend, try to wait */
101 thread->refcount++;
102 THREAD_LIST_UNLOCK(curthread);
103 suspend_common(curthread, thread, 1);
104 THR_THREAD_UNLOCK(curthread, thread);
105 THREAD_LIST_LOCK(curthread);
106 _thr_ref_delete_unlocked(curthread, thread);
107 /*
108 * Because we were blocked, things may have
109 * been changed, we have to restart the
110 * process.
111 */
112 goto restart;
113 }
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114 THR_THREAD_UNLOCK(curthread, thread);
115 }
116 }
117
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118 THREAD_LIST_UNLOCK(curthread);
119}
120
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121static int
122suspend_common(struct pthread *curthread, struct pthread *thread,
123 int waitok)
71b3fa15 124{
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125 umtx_t tmp;
126
127 while (thread->state != PS_DEAD &&
128 !(thread->flags & THR_FLAGS_SUSPENDED)) {
71b3fa15 129 thread->flags |= THR_FLAGS_NEED_SUSPEND;
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130 tmp = thread->cycle;
131 THR_THREAD_UNLOCK(curthread, thread);
71b3fa15 132 _thr_send_sig(thread, SIGCANCEL);
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133 if (waitok) {
134 _thr_umtx_wait(&thread->cycle, tmp, NULL, 0);
135 THR_THREAD_LOCK(curthread, thread);
136 } else {
137 THR_THREAD_LOCK(curthread, thread);
138 return (0);
139 }
71b3fa15 140 }
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141
142 return (1);
71b3fa15 143}