1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the author nor the names of any co-contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include "namespace.h"
33 #include <errno.h>
34 #include <pthread.h>
35 #include <pthread_np.h>
36 #include "un-namespace.h"
37
38 #include "thr_private.h"
39
40 static int suspend_common(struct pthread *, struct pthread *,
41 int);
42
43 __weak_reference(_pthread_suspend_np, pthread_suspend_np);
44 __weak_reference(_thr_suspend_all_np, pthread_suspend_all_np);
45 __weak_reference(_thr_suspend_all_np, _pthread_suspend_all_np);
46
47 /* Suspend a thread: */
48 int
_pthread_suspend_np(pthread_t thread)49 _pthread_suspend_np(pthread_t thread)
50 {
51 struct pthread *curthread = _get_curthread();
52 int ret;
53
54 /* Suspending the current thread doesn't make sense. */
55 if (thread == _get_curthread())
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);
63 suspend_common(curthread, thread, 1);
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
73 void
_thr_suspend_all_lock(struct pthread * curthread)74 _thr_suspend_all_lock(struct pthread *curthread)
75 {
76 int old;
77
78 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
79 while (_single_thread != NULL) {
80 old = _suspend_all_cycle;
81 _suspend_all_waiters++;
82 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
83 _thr_umtx_wait_uint(&_suspend_all_cycle, old, NULL, 0);
84 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
85 _suspend_all_waiters--;
86 }
87 _single_thread = curthread;
88 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
89 }
90
91 void
_thr_suspend_all_unlock(struct pthread * curthread)92 _thr_suspend_all_unlock(struct pthread *curthread)
93 {
94
95 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
96 _single_thread = NULL;
97 if (_suspend_all_waiters != 0) {
98 _suspend_all_cycle++;
99 _thr_umtx_wake(&_suspend_all_cycle, INT_MAX, 0);
100 }
101 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
102 }
103
104 void
_thr_suspend_all_np(void)105 _thr_suspend_all_np(void)
106 {
107 struct pthread *curthread = _get_curthread();
108 struct pthread *thread;
109 int old_nocancel;
110 int ret;
111
112 old_nocancel = curthread->no_cancel;
113 curthread->no_cancel = 1;
114 _thr_suspend_all_lock(curthread);
115 THREAD_LIST_RDLOCK(curthread);
116 TAILQ_FOREACH(thread, &_thread_list, tle) {
117 if (thread != curthread) {
118 THR_THREAD_LOCK(curthread, thread);
119 if (thread->state != PS_DEAD &&
120 !(thread->flags & THR_FLAGS_SUSPENDED))
121 thread->flags |= THR_FLAGS_NEED_SUSPEND;
122 THR_THREAD_UNLOCK(curthread, thread);
123 }
124 }
125 thr_kill(-1, SIGCANCEL);
126
127 restart:
128 TAILQ_FOREACH(thread, &_thread_list, tle) {
129 if (thread != curthread) {
130 /* First try to suspend the thread without waiting */
131 THR_THREAD_LOCK(curthread, thread);
132 ret = suspend_common(curthread, thread, 0);
133 if (ret == 0) {
134 THREAD_LIST_UNLOCK(curthread);
135 /* Can not suspend, try to wait */
136 THR_REF_ADD(curthread, thread);
137 suspend_common(curthread, thread, 1);
138 THR_REF_DEL(curthread, thread);
139 _thr_try_gc(curthread, thread);
140 /* thread lock released */
141
142 THREAD_LIST_RDLOCK(curthread);
143 /*
144 * Because we were blocked, things may have
145 * been changed, we have to restart the
146 * process.
147 */
148 goto restart;
149 }
150 THR_THREAD_UNLOCK(curthread, thread);
151 }
152 }
153 THREAD_LIST_UNLOCK(curthread);
154 _thr_suspend_all_unlock(curthread);
155 curthread->no_cancel = old_nocancel;
156 _thr_testcancel(curthread);
157 }
158
159 static int
suspend_common(struct pthread * curthread,struct pthread * thread,int waitok)160 suspend_common(struct pthread *curthread, struct pthread *thread,
161 int waitok)
162 {
163 uint32_t tmp;
164
165 while (thread->state != PS_DEAD &&
166 !(thread->flags & THR_FLAGS_SUSPENDED)) {
167 thread->flags |= THR_FLAGS_NEED_SUSPEND;
168 /* Thread is in creation. */
169 if (thread->tid == TID_TERMINATED)
170 return (1);
171 tmp = thread->cycle;
172 _thr_send_sig(thread, SIGCANCEL);
173 THR_THREAD_UNLOCK(curthread, thread);
174 if (waitok) {
175 _thr_umtx_wait_uint(&thread->cycle, tmp, NULL, 0);
176 THR_THREAD_LOCK(curthread, thread);
177 } else {
178 THR_THREAD_LOCK(curthread, thread);
179 return (0);
180 }
181 }
182
183 return (1);
184 }
185