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