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 $ 62 * $DragonFly: src/lib/libthread_xu/thread/thr_fork.c,v 1.2 2005/03/15 11:24:23 davidxu Exp $ 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 77 int 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); 106 107 pid_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); 132 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 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 } 229