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. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by John Birrell.
16  * 4. Neither the name of the author nor the names of any co-contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  * $DragonFly: src/lib/libthread_xu/thread/thr_suspend_np.c,v 1.5 2006/04/06 13:03:09 davidxu Exp $
33  */
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 /* Suspend a thread: */
47 int
48 _pthread_suspend_np(pthread_t thread)
49 {
50 	struct pthread *curthread = tls_get_curthread();
51 	int ret;
52 
53 	/* Suspending the current thread doesn't make sense. */
54 	if (thread == 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
73 _pthread_suspend_all_np(void)
74 {
75 	struct pthread *curthread = tls_get_curthread();
76 	struct pthread *thread;
77 	int ret;
78 
79 	THREAD_LIST_LOCK(curthread);
80 
81 	TAILQ_FOREACH(thread, &_thread_list, tle) {
82 		if (thread != curthread) {
83 			THR_THREAD_LOCK(curthread, thread);
84 			if (thread->state != PS_DEAD &&
85 	      		   !(thread->flags & THR_FLAGS_SUSPENDED))
86 			    thread->flags |= THR_FLAGS_NEED_SUSPEND;
87 			THR_THREAD_UNLOCK(curthread, thread);
88 		}
89 	}
90 	/* thr_kill(-1, SIGCANCEL); */
91 
92 restart:
93 	TAILQ_FOREACH(thread, &_thread_list, tle) {
94 		if (thread != curthread) {
95 			/* First try to suspend the thread without waiting */
96 			THR_THREAD_LOCK(curthread, thread);
97 			ret = suspend_common(curthread, thread, 0);
98 			if (ret == 0) {
99 				/* Can not suspend, try to wait */
100 				thread->refcount++;
101 				THREAD_LIST_UNLOCK(curthread);
102 				suspend_common(curthread, thread, 1);
103 				THR_THREAD_UNLOCK(curthread, thread);
104 				THREAD_LIST_LOCK(curthread);
105 				_thr_ref_delete_unlocked(curthread, thread);
106 				/*
107 				 * Because we were blocked, things may have
108 				 * been changed, we have to restart the
109 				 * process.
110 				 */
111 				goto restart;
112 			}
113 			THR_THREAD_UNLOCK(curthread, thread);
114 		}
115 	}
116 
117 	THREAD_LIST_UNLOCK(curthread);
118 }
119 
120 static int
121 suspend_common(struct pthread *curthread, struct pthread *thread,
122 	int waitok)
123 {
124 	umtx_t tmp;
125 
126 	while (thread->state != PS_DEAD &&
127 	      !(thread->flags & THR_FLAGS_SUSPENDED)) {
128 		thread->flags |= THR_FLAGS_NEED_SUSPEND;
129 		tmp = thread->cycle;
130 		_thr_send_sig(thread, SIGCANCEL);
131 		THR_THREAD_UNLOCK(curthread, thread);
132 		if (waitok) {
133 			_thr_umtx_wait(&thread->cycle, tmp, NULL, 0);
134 			THR_THREAD_LOCK(curthread, thread);
135 		} else {
136 			THR_THREAD_LOCK(curthread, thread);
137 			return (0);
138 		}
139 	}
140 
141 	return (1);
142 }
143 
144 __strong_reference(_pthread_suspend_np, pthread_suspend_np);
145 __strong_reference(_pthread_suspend_all_np, pthread_suspend_all_np);
146 
147