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 1.3 2005/03/29 19:26:20 joerg Exp $ 63 */ 64 65 #include <machine/tls.h> 66 67 #include <errno.h> 68 #include <string.h> 69 #include <stdlib.h> 70 #include <unistd.h> 71 #include <fcntl.h> 72 #include <pthread.h> 73 #include <spinlock.h> 74 75 #include "libc_private.h" 76 #include "thr_private.h" 77 78 __weak_reference(_pthread_atfork, pthread_atfork); 79 80 int 81 _pthread_atfork(void (*prepare)(void), void (*parent)(void), 82 void (*child)(void)) 83 { 84 struct pthread *curthread; 85 struct pthread_atfork *af; 86 87 _thr_check_init(); 88 89 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 90 return (ENOMEM); 91 92 curthread = tls_get_curthread(); 93 af->prepare = prepare; 94 af->parent = parent; 95 af->child = child; 96 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 97 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 98 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 99 return (0); 100 } 101 102 /* 103 * For a while, allow libpthread to work with a libc that doesn't 104 * export the malloc lock. 105 */ 106 #pragma weak __malloc_lock 107 108 __weak_reference(_fork, fork); 109 110 pid_t 111 _fork(void) 112 { 113 static umtx_t inprogress; 114 static int waiters; 115 umtx_t tmp; 116 117 struct pthread *curthread; 118 struct pthread_atfork *af; 119 pid_t ret; 120 int errsave; 121 #ifndef __DragonFly__ 122 int unlock_malloc; 123 #endif 124 125 if (!_thr_is_inited()) 126 return (__sys_fork()); 127 128 curthread = tls_get_curthread(); 129 130 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 131 tmp = inprogress; 132 while (tmp) { 133 waiters++; 134 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 135 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 136 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 137 waiters--; 138 tmp = inprogress; 139 } 140 inprogress = 1; 141 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 142 143 /* Run down atfork prepare handlers. */ 144 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 145 if (af->prepare != NULL) 146 af->prepare(); 147 } 148 149 #ifndef __DragonFly__ 150 /* 151 * Try our best to protect memory from being corrupted in 152 * child process because another thread in malloc code will 153 * simply be kill by fork(). 154 */ 155 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 156 unlock_malloc = 1; 157 _spinlock(__malloc_lock); 158 } else { 159 unlock_malloc = 0; 160 } 161 #endif 162 163 /* 164 * Block all signals until we reach a safe point. 165 */ 166 _thr_signal_block(curthread); 167 168 /* Fork a new process: */ 169 if ((ret = __sys_fork()) == 0) { 170 /* Child process */ 171 errsave = errno; 172 inprogress = 0; 173 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 174 /* 175 * Thread list will be reinitialized, and later we call 176 * _libpthread_init(), it will add us back to list. 177 */ 178 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 179 180 /* child is a new kernel thread. */ 181 curthread->tid = _thr_get_tid(); 182 183 /* clear other threads locked us. */ 184 _thr_umtx_init(&curthread->lock); 185 _thr_umtx_init(&_thr_atfork_lock); 186 _thr_setthreaded(0); 187 188 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 189 _thr_spinlock_init(); 190 _mutex_fork(curthread); 191 192 /* reinitalize library. */ 193 _libpthread_init(curthread); 194 195 /* Ready to continue, unblock signals. */ 196 _thr_signal_unblock(curthread); 197 198 /* Run down atfork child handlers. */ 199 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 200 if (af->child != NULL) 201 af->child(); 202 } 203 } else { 204 /* Parent process */ 205 errsave = errno; 206 207 #ifndef __DragonFly__ 208 if (unlock_malloc) 209 _spinunlock(__malloc_lock); 210 #endif 211 212 /* Ready to continue, unblock signals. */ 213 _thr_signal_unblock(curthread); 214 215 /* Run down atfork parent handlers. */ 216 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 217 if (af->parent != NULL) 218 af->parent(); 219 } 220 221 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 222 inprogress = 0; 223 if (waiters) 224 _thr_umtx_wake(&inprogress, waiters); 225 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 226 } 227 errno = errsave; 228 229 /* Return the process ID: */ 230 return (ret); 231 } 232