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 <sys/cdefs.h>
33 __FBSDID("$FreeBSD: stable/12/lib/libthr/thread/thr_suspend_np.c 326025 2017-11-20 19:49:47Z pfg $");
34
35 #include "namespace.h"
36 #include <errno.h>
37 #include <pthread.h>
38 #include <pthread_np.h>
39 #include "un-namespace.h"
40
41 #include "thr_private.h"
42
43 static int suspend_common(struct pthread *, struct pthread *,
44 int);
45
46 __weak_reference(_pthread_suspend_np, pthread_suspend_np);
47 __weak_reference(_pthread_suspend_all_np, pthread_suspend_all_np);
48
49 /* Suspend a thread: */
50 int
_pthread_suspend_np(pthread_t thread)51 _pthread_suspend_np(pthread_t thread)
52 {
53 struct pthread *curthread = _get_curthread();
54 int ret;
55
56 /* Suspending the current thread doesn't make sense. */
57 if (thread == _get_curthread())
58 ret = EDEADLK;
59
60 /* Add a reference to the thread: */
61 else if ((ret = _thr_ref_add(curthread, thread, /*include dead*/0))
62 == 0) {
63 /* Lock the threads scheduling queue: */
64 THR_THREAD_LOCK(curthread, thread);
65 suspend_common(curthread, thread, 1);
66 /* Unlock the threads scheduling queue: */
67 THR_THREAD_UNLOCK(curthread, thread);
68
69 /* Don't forget to remove the reference: */
70 _thr_ref_delete(curthread, thread);
71 }
72 return (ret);
73 }
74
75 void
_thr_suspend_all_lock(struct pthread * curthread)76 _thr_suspend_all_lock(struct pthread *curthread)
77 {
78 int old;
79
80 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
81 while (_single_thread != NULL) {
82 old = _suspend_all_cycle;
83 _suspend_all_waiters++;
84 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
85 _thr_umtx_wait_uint(&_suspend_all_cycle, old, NULL, 0);
86 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
87 _suspend_all_waiters--;
88 }
89 _single_thread = curthread;
90 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
91 }
92
93 void
_thr_suspend_all_unlock(struct pthread * curthread)94 _thr_suspend_all_unlock(struct pthread *curthread)
95 {
96
97 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
98 _single_thread = NULL;
99 if (_suspend_all_waiters != 0) {
100 _suspend_all_cycle++;
101 _thr_umtx_wake(&_suspend_all_cycle, INT_MAX, 0);
102 }
103 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
104 }
105
106 void
_pthread_suspend_all_np(void)107 _pthread_suspend_all_np(void)
108 {
109 struct pthread *curthread = _get_curthread();
110 struct pthread *thread;
111 int old_nocancel;
112 int ret;
113
114 old_nocancel = curthread->no_cancel;
115 curthread->no_cancel = 1;
116 _thr_suspend_all_lock(curthread);
117 THREAD_LIST_RDLOCK(curthread);
118 TAILQ_FOREACH(thread, &_thread_list, tle) {
119 if (thread != curthread) {
120 THR_THREAD_LOCK(curthread, thread);
121 if (thread->state != PS_DEAD &&
122 !(thread->flags & THR_FLAGS_SUSPENDED))
123 thread->flags |= THR_FLAGS_NEED_SUSPEND;
124 THR_THREAD_UNLOCK(curthread, thread);
125 }
126 }
127 thr_kill(-1, SIGCANCEL);
128
129 restart:
130 TAILQ_FOREACH(thread, &_thread_list, tle) {
131 if (thread != curthread) {
132 /* First try to suspend the thread without waiting */
133 THR_THREAD_LOCK(curthread, thread);
134 ret = suspend_common(curthread, thread, 0);
135 if (ret == 0) {
136 THREAD_LIST_UNLOCK(curthread);
137 /* Can not suspend, try to wait */
138 THR_REF_ADD(curthread, thread);
139 suspend_common(curthread, thread, 1);
140 THR_REF_DEL(curthread, thread);
141 _thr_try_gc(curthread, thread);
142 /* thread lock released */
143
144 THREAD_LIST_RDLOCK(curthread);
145 /*
146 * Because we were blocked, things may have
147 * been changed, we have to restart the
148 * process.
149 */
150 goto restart;
151 }
152 THR_THREAD_UNLOCK(curthread, thread);
153 }
154 }
155 THREAD_LIST_UNLOCK(curthread);
156 _thr_suspend_all_unlock(curthread);
157 curthread->no_cancel = old_nocancel;
158 _thr_testcancel(curthread);
159 }
160
161 static int
suspend_common(struct pthread * curthread,struct pthread * thread,int waitok)162 suspend_common(struct pthread *curthread, struct pthread *thread,
163 int waitok)
164 {
165 uint32_t tmp;
166
167 while (thread->state != PS_DEAD &&
168 !(thread->flags & THR_FLAGS_SUSPENDED)) {
169 thread->flags |= THR_FLAGS_NEED_SUSPEND;
170 /* Thread is in creation. */
171 if (thread->tid == TID_TERMINATED)
172 return (1);
173 tmp = thread->cycle;
174 _thr_send_sig(thread, SIGCANCEL);
175 THR_THREAD_UNLOCK(curthread, thread);
176 if (waitok) {
177 _thr_umtx_wait_uint(&thread->cycle, tmp, NULL, 0);
178 THR_THREAD_LOCK(curthread, thread);
179 } else {
180 THR_THREAD_LOCK(curthread, thread);
181 return (0);
182 }
183 }
184
185 return (1);
186 }
187