thr_fork.c revision 154248
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 154248 2006-01-12 07:28:21Z jasone $ 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 <errno.h> 64#include <string.h> 65#include <stdlib.h> 66#include <unistd.h> 67#include <pthread.h> 68#include <spinlock.h> 69 70#include "libc_private.h" 71#include "thr_private.h" 72 73__weak_reference(_pthread_atfork, pthread_atfork); 74 75int 76_pthread_atfork(void (*prepare)(void), void (*parent)(void), 77 void (*child)(void)) 78{ 79 struct pthread *curthread; 80 struct pthread_atfork *af; 81 82 _thr_check_init(); 83 84 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 85 return (ENOMEM); 86 87 curthread = _get_curthread(); 88 af->prepare = prepare; 89 af->parent = parent; 90 af->child = child; 91 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 92 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 93 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 94 return (0); 95} 96 97__weak_reference(_fork, fork); 98 99pid_t 100_fork(void) 101{ 102 struct pthread *curthread; 103 struct pthread_atfork *af; 104 pid_t ret; 105 int errsave; 106 int unlock_malloc; 107 108 if (!_thr_is_inited()) 109 return (__sys_fork()); 110 111 curthread = _get_curthread(); 112 113 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 114 115 /* Run down atfork prepare handlers. */ 116 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 117 if (af->prepare != NULL) 118 af->prepare(); 119 } 120 121 /* 122 * Try our best to protect memory from being corrupted in 123 * child process because another thread in malloc code will 124 * simply be kill by fork(). 125 */ 126 if (_thr_isthreaded() != 0) { 127 unlock_malloc = 1; 128 _malloc_prefork(); 129 } else { 130 unlock_malloc = 0; 131 } 132 133 /* 134 * Block all signals until we reach a safe point. 135 */ 136 _thr_signal_block(curthread); 137 138 /* Fork a new process: */ 139 if ((ret = __sys_fork()) == 0) { 140 /* Child process */ 141 errsave = errno; 142 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 143 /* 144 * Thread list will be reinitialized, and later we call 145 * _libpthread_init(), it will add us back to list. 146 */ 147 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 148 149 /* child is a new kernel thread. */ 150 thr_self(&curthread->tid); 151 152 /* clear other threads locked us. */ 153 _thr_umtx_init(&curthread->lock); 154 _thr_umtx_init(&_thr_atfork_lock); 155 _thr_setthreaded(0); 156 157 /* reinitialize libc spinlocks. */ 158 _thr_spinlock_init(); 159 _mutex_fork(curthread); 160 161 /* reinitalize library. */ 162 _libpthread_init(curthread); 163 164 /* Ready to continue, unblock signals. */ 165 _thr_signal_unblock(curthread); 166 167 /* Run down atfork child handlers. */ 168 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 169 if (af->child != NULL) 170 af->child(); 171 } 172 } else { 173 /* Parent process */ 174 errsave = errno; 175 176 /* Ready to continue, unblock signals. */ 177 _thr_signal_unblock(curthread); 178 179 if (unlock_malloc) 180 _malloc_postfork(); 181 182 /* Run down atfork parent handlers. */ 183 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 184 if (af->parent != NULL) 185 af->parent(); 186 } 187 188 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 189 } 190 errno = errsave; 191 192 /* Return the process ID: */ 193 return (ret); 194} 195