thr_suspend_np.c revision 331722 
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. Neither the name of the author nor the names of any co-contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: stable/11/lib/libthr/thread/thr_suspend_np.c 331722 2018-03-29 02:50:57Z eadler $");
32
33#include "namespace.h"
34#include <errno.h>
35#include <pthread.h>
36#include <pthread_np.h>
37#include "un-namespace.h"
38
39#include "thr_private.h"
40
41static int suspend_common(struct pthread *, struct pthread *,
42		int);
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{
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
73void
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
91void
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
104void
105_pthread_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
127restart:
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
159static int
160suspend_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