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 * $FreeBSD$ 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 75 int 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 /* 98 * For a while, allow libpthread to work with a libc that doesn't 99 * export the malloc lock. 100 */ 101 #pragma weak __malloc_lock 102 103 __weak_reference(_fork, fork); 104 105 pid_t 106 _fork(void) 107 { 108 static umtx_t inprogress; 109 static int waiters; 110 umtx_t tmp; 111 112 struct pthread *curthread; 113 struct pthread_atfork *af; 114 pid_t ret; 115 int errsave; 116 int unlock_malloc; 117 118 if (!_thr_is_inited()) 119 return (__sys_fork()); 120 121 curthread = _get_curthread(); 122 123 /* 124 * Block all signals until we reach a safe point. 125 */ 126 _thr_signal_block(curthread); 127 128 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 129 tmp = inprogress; 130 while (tmp) { 131 waiters++; 132 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 133 _thr_umtx_wait(&inprogress, tmp, NULL); 134 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 135 waiters--; 136 tmp = inprogress; 137 } 138 inprogress = 1; 139 140 /* Unlock mutex, allow new hook to be added during executing hooks. */ 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 /* 150 * Try our best to protect memory from being corrupted in 151 * child process because another thread in malloc code will 152 * simply be kill by fork(). 153 */ 154 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 155 unlock_malloc = 1; 156 _spinlock(__malloc_lock); 157 } else { 158 unlock_malloc = 0; 159 } 160 161 /* Fork a new process: */ 162 if ((ret = __sys_fork()) == 0) { 163 /* Child process */ 164 errsave = errno; 165 inprogress = 0; 166 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 167 /* 168 * Thread list will be reinitialized, and later we call 169 * _libpthread_init(), it will add us back to list. 170 */ 171 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 172 173 /* child is a new kernel thread. */ 174 thr_self(&curthread->tid); 175 176 /* clear other threads locked us. */ 177 _thr_umtx_init(&curthread->lock); 178 _thr_umtx_init(&_thr_atfork_lock); 179 _thr_setthreaded(0); 180 181 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 182 _thr_spinlock_init(); 183 _mutex_fork(curthread); 184 185 /* reinitalize library. */ 186 _libpthread_init(curthread); 187 188 /* Ready to continue, unblock signals. */ 189 _thr_signal_unblock(curthread); 190 191 /* Run down atfork child handlers. */ 192 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 193 if (af->child != NULL) 194 af->child(); 195 } 196 } else { 197 /* Parent process */ 198 errsave = errno; 199 200 if (unlock_malloc) 201 _spinunlock(__malloc_lock); 202 203 /* Ready to continue, unblock signals. */ 204 _thr_signal_unblock(curthread); 205 206 /* Run down atfork parent handlers. */ 207 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 208 if (af->parent != NULL) 209 af->parent(); 210 } 211 212 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 213 inprogress = 0; 214 if (waiters) 215 _thr_umtx_wake(&inprogress, waiters); 216 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 217 } 218 errno = errsave; 219 220 /* Return the process ID: */ 221 return (ret); 222 } 223