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 1.6 2006/04/06 13:03:09 davidxu Exp $ 63 */ 64 65 #include "namespace.h" 66 #include <machine/tls.h> 67 68 #include <errno.h> 69 #include <string.h> 70 #include <stdlib.h> 71 #include <unistd.h> 72 #include <fcntl.h> 73 #include <pthread.h> 74 #include <spinlock.h> 75 #include "un-namespace.h" 76 77 #include "libc_private.h" 78 #include "thr_private.h" 79 80 struct atfork_head _thr_atfork_list; 81 umtx_t _thr_atfork_lock; 82 83 int 84 _pthread_atfork(void (*prepare)(void), void (*parent)(void), 85 void (*child)(void)) 86 { 87 struct pthread *curthread; 88 struct pthread_atfork *af; 89 90 _thr_check_init(); 91 92 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 93 return (ENOMEM); 94 95 curthread = tls_get_curthread(); 96 af->prepare = prepare; 97 af->parent = parent; 98 af->child = child; 99 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 100 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 101 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 102 return (0); 103 } 104 105 /* 106 * For a while, allow libpthread to work with a libc that doesn't 107 * export the malloc lock. 108 */ 109 #pragma weak __malloc_lock 110 111 pid_t _fork(void); 112 113 pid_t 114 _fork(void) 115 { 116 static umtx_t inprogress; 117 static int waiters; 118 umtx_t tmp; 119 120 struct pthread *curthread; 121 struct pthread_atfork *af; 122 pid_t ret; 123 int errsave; 124 #ifndef __DragonFly__ 125 int unlock_malloc; 126 #endif 127 128 if (!_thr_is_inited()) 129 return (__sys_fork()); 130 131 curthread = tls_get_curthread(); 132 133 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 134 tmp = inprogress; 135 while (tmp) { 136 waiters++; 137 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 138 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 139 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 140 waiters--; 141 tmp = inprogress; 142 } 143 inprogress = 1; 144 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 145 146 /* Run down atfork prepare handlers. */ 147 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 148 if (af->prepare != NULL) 149 af->prepare(); 150 } 151 152 #ifndef __DragonFly__ 153 /* 154 * Try our best to protect memory from being corrupted in 155 * child process because another thread in malloc code will 156 * simply be kill by fork(). 157 */ 158 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 159 unlock_malloc = 1; 160 _spinlock(__malloc_lock); 161 } else { 162 unlock_malloc = 0; 163 } 164 #endif 165 166 /* 167 * Block all signals until we reach a safe point. 168 */ 169 _thr_signal_block(curthread); 170 171 /* Fork a new process: */ 172 if ((ret = __sys_fork()) == 0) { 173 /* Child process */ 174 errsave = errno; 175 inprogress = 0; 176 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 177 /* 178 * Thread list will be reinitialized, and later we call 179 * _libpthread_init(), it will add us back to list. 180 */ 181 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 182 183 /* child is a new kernel thread. */ 184 curthread->tid = _thr_get_tid(); 185 186 /* clear other threads locked us. */ 187 _thr_umtx_init(&curthread->lock); 188 _thr_umtx_init(&_thr_atfork_lock); 189 _thr_setthreaded(0); 190 191 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 192 _thr_spinlock_init(); 193 _mutex_fork(curthread); 194 195 /* reinitalize library. */ 196 _libpthread_init(curthread); 197 198 /* Ready to continue, unblock signals. */ 199 _thr_signal_unblock(curthread); 200 201 /* Run down atfork child handlers. */ 202 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 203 if (af->child != NULL) 204 af->child(); 205 } 206 } else { 207 /* Parent process */ 208 errsave = errno; 209 210 #ifndef __DragonFly__ 211 if (unlock_malloc) 212 _spinunlock(__malloc_lock); 213 #endif 214 215 /* Ready to continue, unblock signals. */ 216 _thr_signal_unblock(curthread); 217 218 /* Run down atfork parent handlers. */ 219 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 220 if (af->parent != NULL) 221 af->parent(); 222 } 223 224 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 225 inprogress = 0; 226 if (waiters) 227 _thr_umtx_wake(&inprogress, waiters); 228 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 229 } 230 errno = errsave; 231 232 /* Return the process ID: */ 233 return (ret); 234 } 235 236 __strong_reference(_fork, fork); 237 __strong_reference(_pthread_atfork, pthread_atfork); 238 239