thr_fork.c revision 157457
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: head/lib/libthr/thread/thr_fork.c 157457 2006-04-04 02:57:49Z davidxu $ 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 */ 62 63#include "namespace.h" 64#include <errno.h> 65#include <string.h> 66#include <stdlib.h> 67#include <unistd.h> 68#include <pthread.h> 69#include <spinlock.h> 70#include "un-namespace.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__weak_reference(_fork, fork); 100 101pid_t _fork(void); 102 103pid_t 104_fork(void) 105{ 106 struct pthread *curthread; 107 struct pthread_atfork *af; 108 pid_t ret; 109 int errsave; 110 int unlock_malloc; 111 112 if (!_thr_is_inited()) 113 return (__sys_fork()); 114 115 curthread = _get_curthread(); 116 117 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 118 119 /* Run down atfork prepare handlers. */ 120 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 121 if (af->prepare != NULL) 122 af->prepare(); 123 } 124 125 /* 126 * Try our best to protect memory from being corrupted in 127 * child process because another thread in malloc code will 128 * simply be kill by fork(). 129 */ 130 if (_thr_isthreaded() != 0) { 131 unlock_malloc = 1; 132 _malloc_prefork(); 133 } else { 134 unlock_malloc = 0; 135 } 136 137 /* 138 * Block all signals until we reach a safe point. 139 */ 140 _thr_signal_block(curthread); 141 142 /* Fork a new process: */ 143 if ((ret = __sys_fork()) == 0) { 144 /* Child process */ 145 errsave = errno; 146 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 147 /* 148 * Thread list will be reinitialized, and later we call 149 * _libpthread_init(), it will add us back to list. 150 */ 151 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 152 153 /* child is a new kernel thread. */ 154 thr_self(&curthread->tid); 155 156 /* clear other threads locked us. */ 157 _thr_umtx_init(&curthread->lock); 158 _thr_umtx_init(&_thr_atfork_lock); 159 _thr_setthreaded(0); 160 161 /* reinitialize libc spinlocks. */ 162 _thr_spinlock_init(); 163 _mutex_fork(curthread); 164 165 /* reinitalize library. */ 166 _libpthread_init(curthread); 167 168 /* Ready to continue, unblock signals. */ 169 _thr_signal_unblock(curthread); 170 171 /* Run down atfork child handlers. */ 172 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 173 if (af->child != NULL) 174 af->child(); 175 } 176 } else { 177 /* Parent process */ 178 errsave = errno; 179 180 /* Ready to continue, unblock signals. */ 181 _thr_signal_unblock(curthread); 182 183 if (unlock_malloc) 184 _malloc_postfork(); 185 186 /* Run down atfork parent handlers. */ 187 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 188 if (af->parent != NULL) 189 af->parent(); 190 } 191 192 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 193 } 194 errno = errsave; 195 196 /* Return the process ID: */ 197 return (ret); 198} 199