Merge from vendor branch HEIMDAL:
[dragonfly.git] / lib / libthread_xu / thread / thr_fork.c
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1/*
2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
3 * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Neither the name of the author nor the names of any co-contributors
12 * may be used to endorse or promote products derived from this software
13 * without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD: src/lib/libpthread/thread/thr_atfork.c,v 1.1 2003/11/05 03:42:10 davidxu Exp $
28 */
29
30/*
31 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
32 * All rights reserved.
33 *
34 * Redistribution and use in source and binary forms, with or without
35 * modification, are permitted provided that the following conditions
36 * are met:
37 * 1. Redistributions of source code must retain the above copyright
38 * notice, this list of conditions and the following disclaimer.
39 * 2. Redistributions in binary form must reproduce the above copyright
40 * notice, this list of conditions and the following disclaimer in the
41 * documentation and/or other materials provided with the distribution.
42 * 3. All advertising materials mentioning features or use of this software
43 * must display the following acknowledgement:
44 * This product includes software developed by John Birrell.
45 * 4. Neither the name of the author nor the names of any co-contributors
46 * may be used to endorse or promote products derived from this software
47 * without specific prior written permission.
48 *
49 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59 * SUCH DAMAGE.
60 *
61 * $FreeBSD: src/lib/libpthread/thread/thr_fork.c,v 1.34 2003/11/05 18:18:45 deischen Exp $
9219c44c 62 * $DragonFly: src/lib/libthread_xu/thread/thr_fork.c,v 1.2 2005/03/15 11:24:23 davidxu Exp $
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63 */
64#include <errno.h>
65#include <string.h>
66#include <stdlib.h>
67#include <unistd.h>
68#include <fcntl.h>
69#include <pthread.h>
70#include <spinlock.h>
71
72#include "libc_private.h"
73#include "thr_private.h"
74
75__weak_reference(_pthread_atfork, pthread_atfork);
76
77int
78_pthread_atfork(void (*prepare)(void), void (*parent)(void),
79 void (*child)(void))
80{
81 struct pthread *curthread;
82 struct pthread_atfork *af;
83
84 _thr_check_init();
85
86 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
87 return (ENOMEM);
88
89 curthread = _get_curthread();
90 af->prepare = prepare;
91 af->parent = parent;
92 af->child = child;
93 THR_UMTX_LOCK(curthread, &_thr_atfork_lock);
94 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
95 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock);
96 return (0);
97}
98
99/*
100 * For a while, allow libpthread to work with a libc that doesn't
101 * export the malloc lock.
102 */
103#pragma weak __malloc_lock
104
105__weak_reference(_fork, fork);
106
107pid_t
108_fork(void)
109{
110 static umtx_t inprogress;
111 static int waiters;
112 umtx_t tmp;
113
114 struct pthread *curthread;
115 struct pthread_atfork *af;
116 pid_t ret;
117 int errsave;
118#ifndef __DragonFly__
119 int unlock_malloc;
120#endif
121
122 if (!_thr_is_inited())
123 return (__sys_fork());
124
125 curthread = _get_curthread();
126
127 THR_UMTX_LOCK(curthread, &_thr_atfork_lock);
128 tmp = inprogress;
129 while (tmp) {
130 waiters++;
131 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock);
9219c44c 132 _thr_umtx_wait(&inprogress, tmp, NULL, 0);
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133 THR_UMTX_LOCK(curthread, &_thr_atfork_lock);
134 waiters--;
135 tmp = inprogress;
136 }
137 inprogress = 1;
138 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock);
139
140 /* Run down atfork prepare handlers. */
141 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
142 if (af->prepare != NULL)
143 af->prepare();
144 }
145
146#ifndef __DragonFly__
147 /*
148 * Try our best to protect memory from being corrupted in
149 * child process because another thread in malloc code will
150 * simply be kill by fork().
151 */
152 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) {
153 unlock_malloc = 1;
154 _spinlock(__malloc_lock);
155 } else {
156 unlock_malloc = 0;
157 }
158#endif
159
160 /*
161 * Block all signals until we reach a safe point.
162 */
163 _thr_signal_block(curthread);
164
165 /* Fork a new process: */
166 if ((ret = __sys_fork()) == 0) {
167 /* Child process */
168 errsave = errno;
169 inprogress = 0;
170 curthread->cancelflags &= ~THR_CANCEL_NEEDED;
171 /*
172 * Thread list will be reinitialized, and later we call
173 * _libpthread_init(), it will add us back to list.
174 */
175 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED);
176
177 /* child is a new kernel thread. */
178 curthread->tid = _thr_get_tid();
179
180 /* clear other threads locked us. */
181 _thr_umtx_init(&curthread->lock);
182 _thr_umtx_init(&_thr_atfork_lock);
183 _thr_setthreaded(0);
184
185 /* reinitialize libc spinlocks, this includes __malloc_lock. */
186 _thr_spinlock_init();
187 _mutex_fork(curthread);
188
189 /* reinitalize library. */
190 _libpthread_init(curthread);
191
192 /* Ready to continue, unblock signals. */
193 _thr_signal_unblock(curthread);
194
195 /* Run down atfork child handlers. */
196 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
197 if (af->child != NULL)
198 af->child();
199 }
200 } else {
201 /* Parent process */
202 errsave = errno;
203
204#ifndef __DragonFly__
205 if (unlock_malloc)
206 _spinunlock(__malloc_lock);
207#endif
208
209 /* Ready to continue, unblock signals. */
210 _thr_signal_unblock(curthread);
211
212 /* Run down atfork parent handlers. */
213 TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
214 if (af->parent != NULL)
215 af->parent();
216 }
217
218 THR_UMTX_LOCK(curthread, &_thr_atfork_lock);
219 inprogress = 0;
220 if (waiters)
221 _thr_umtx_wake(&inprogress, waiters);
222 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock);
223 }
224 errno = errsave;
225
226 /* Return the process ID: */
227 return (ret);
228}