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(_pthread_suspend_all_np, pthread_suspend_all_np);
45
46 /* Suspend a thread: */
47 int
_pthread_suspend_np(pthread_t thread)48 _pthread_suspend_np(pthread_t thread)
49 {
50 struct pthread *curthread = _get_curthread();
51 int ret;
52
53 /* Suspending the current thread doesn't make sense. */
54 if (thread == _get_curthread())
55 ret = EDEADLK;
56
57 /* Add a reference to the thread: */
58 else if ((ret = _thr_ref_add(curthread, thread, /*include dead*/0))
59 == 0) {
60 /* Lock the threads scheduling queue: */
61 THR_THREAD_LOCK(curthread, thread);
62 suspend_common(curthread, thread, 1);
63 /* Unlock the threads scheduling queue: */
64 THR_THREAD_UNLOCK(curthread, thread);
65
66 /* Don't forget to remove the reference: */
67 _thr_ref_delete(curthread, thread);
68 }
69 return (ret);
70 }
71
72 void
_thr_suspend_all_lock(struct pthread * curthread)73 _thr_suspend_all_lock(struct pthread *curthread)
74 {
75 int old;
76
77 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
78 while (_single_thread != NULL) {
79 old = _suspend_all_cycle;
80 _suspend_all_waiters++;
81 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
82 _thr_umtx_wait_uint(&_suspend_all_cycle, old, NULL, 0);
83 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
84 _suspend_all_waiters--;
85 }
86 _single_thread = curthread;
87 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
88 }
89
90 void
_thr_suspend_all_unlock(struct pthread * curthread)91 _thr_suspend_all_unlock(struct pthread *curthread)
92 {
93
94 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
95 _single_thread = NULL;
96 if (_suspend_all_waiters != 0) {
97 _suspend_all_cycle++;
98 _thr_umtx_wake(&_suspend_all_cycle, INT_MAX, 0);
99 }
100 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
101 }
102
103 void
_pthread_suspend_all_np(void)104 _pthread_suspend_all_np(void)
105 {
106 struct pthread *curthread = _get_curthread();
107 struct pthread *thread;
108 int old_nocancel;
109 int ret;
110
111 old_nocancel = curthread->no_cancel;
112 curthread->no_cancel = 1;
113 _thr_suspend_all_lock(curthread);
114 THREAD_LIST_RDLOCK(curthread);
115 TAILQ_FOREACH(thread, &_thread_list, tle) {
116 if (thread != curthread) {
117 THR_THREAD_LOCK(curthread, thread);
118 if (thread->state != PS_DEAD &&
119 !(thread->flags & THR_FLAGS_SUSPENDED))
120 thread->flags |= THR_FLAGS_NEED_SUSPEND;
121 THR_THREAD_UNLOCK(curthread, thread);
122 }
123 }
124 thr_kill(-1, SIGCANCEL);
125
126 restart:
127 TAILQ_FOREACH(thread, &_thread_list, tle) {
128 if (thread != curthread) {
129 /* First try to suspend the thread without waiting */
130 THR_THREAD_LOCK(curthread, thread);
131 ret = suspend_common(curthread, thread, 0);
132 if (ret == 0) {
133 THREAD_LIST_UNLOCK(curthread);
134 /* Can not suspend, try to wait */
135 THR_REF_ADD(curthread, thread);
136 suspend_common(curthread, thread, 1);
137 THR_REF_DEL(curthread, thread);
138 _thr_try_gc(curthread, thread);
139 /* thread lock released */
140
141 THREAD_LIST_RDLOCK(curthread);
142 /*
143 * Because we were blocked, things may have
144 * been changed, we have to restart the
145 * process.
146 */
147 goto restart;
148 }
149 THR_THREAD_UNLOCK(curthread, thread);
150 }
151 }
152 THREAD_LIST_UNLOCK(curthread);
153 _thr_suspend_all_unlock(curthread);
154 curthread->no_cancel = old_nocancel;
155 _thr_testcancel(curthread);
156 }
157
158 static int
suspend_common(struct pthread * curthread,struct pthread * thread,int waitok)159 suspend_common(struct pthread *curthread, struct pthread *thread,
160 int waitok)
161 {
162 uint32_t tmp;
163
164 while (thread->state != PS_DEAD &&
165 !(thread->flags & THR_FLAGS_SUSPENDED)) {
166 thread->flags |= THR_FLAGS_NEED_SUSPEND;
167 /* Thread is in creation. */
168 if (thread->tid == TID_TERMINATED)
169 return (1);
170 tmp = thread->cycle;
171 _thr_send_sig(thread, SIGCANCEL);
172 THR_THREAD_UNLOCK(curthread, thread);
173 if (waitok) {
174 _thr_umtx_wait_uint(&thread->cycle, tmp, NULL, 0);
175 THR_THREAD_LOCK(curthread, thread);
176 } else {
177 THR_THREAD_LOCK(curthread, thread);
178 return (0);
179 }
180 }
181
182 return (1);
183 }
184