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 213096 2010-08-23 $ 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. Neither the name of the author nor the names of any co-contributors 43 * may be used to endorse or promote products derived from this software 44 * without specific prior written permission. 45 * 46 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 47 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 48 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 49 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 50 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 51 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 52 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 53 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 54 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 55 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 56 * SUCH DAMAGE. 57 * 58 */ 59 60 #include "namespace.h" 61 #include <machine/tls.h> 62 63 #include <errno.h> 64 #include <link.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 #include "un-namespace.h" 72 73 #include "libc_private.h" 74 #include "thr_private.h" 75 76 struct atfork_head _thr_atfork_list; 77 umtx_t _thr_atfork_lock; 78 79 int 80 _pthread_atfork(void (*prepare)(void), void (*parent)(void), 81 void (*child)(void)) 82 { 83 struct pthread *curthread; 84 struct pthread_atfork *af; 85 86 _thr_check_init(); 87 88 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 89 return (ENOMEM); 90 91 curthread = tls_get_curthread(); 92 af->prepare = prepare; 93 af->parent = parent; 94 af->child = child; 95 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 96 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 97 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 98 return (0); 99 } 100 101 void 102 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info) 103 { 104 struct pthread *curthread; 105 struct pthread_atfork *af, *af1; 106 107 _thr_check_init(); 108 109 curthread = tls_get_curthread(); 110 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 111 TAILQ_FOREACH_MUTABLE(af, &_thr_atfork_list, qe, af1) { 112 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 113 __elf_phdr_match_addr(phdr_info, af->parent) || 114 __elf_phdr_match_addr(phdr_info, af->child)) { 115 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 116 free(af); 117 } 118 } 119 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 120 } 121 122 /* 123 * For a while, allow libpthread to work with a libc that doesn't 124 * export the malloc lock. 125 */ 126 #pragma weak __malloc_lock 127 128 pid_t _fork(void); 129 130 pid_t 131 _fork(void) 132 { 133 static umtx_t inprogress; 134 static int waiters; 135 umtx_t tmp; 136 137 struct pthread *curthread; 138 struct pthread_atfork *af; 139 pid_t ret; 140 int errsave; 141 #ifndef __DragonFly__ 142 int unlock_malloc; 143 #endif 144 145 if (!_thr_is_inited()) 146 return (__sys_fork()); 147 148 curthread = tls_get_curthread(); 149 150 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 151 tmp = inprogress; 152 while (tmp) { 153 waiters++; 154 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 155 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 156 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 157 waiters--; 158 tmp = inprogress; 159 } 160 inprogress = 1; 161 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 162 163 /* Run down atfork prepare handlers. */ 164 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 165 if (af->prepare != NULL) 166 af->prepare(); 167 } 168 169 #ifndef __DragonFly__ 170 /* 171 * Try our best to protect memory from being corrupted in 172 * child process because another thread in malloc code will 173 * simply be kill by fork(). 174 */ 175 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 176 unlock_malloc = 1; 177 _spinlock(__malloc_lock); 178 } else { 179 unlock_malloc = 0; 180 } 181 #endif 182 183 /* 184 * Block all signals until we reach a safe point. 185 */ 186 _thr_signal_block(curthread); 187 188 /* Fork a new process: */ 189 if ((ret = __sys_fork()) == 0) { 190 /* Child process */ 191 errsave = errno; 192 inprogress = 0; 193 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 194 /* 195 * Thread list will be reinitialized, and later we call 196 * _libpthread_init(), it will add us back to list. 197 */ 198 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 199 200 /* child is a new kernel thread. */ 201 curthread->tid = _thr_get_tid(); 202 203 /* clear other threads locked us. */ 204 _thr_umtx_init(&curthread->lock); 205 _thr_umtx_init(&_thr_atfork_lock); 206 _thr_setthreaded(0); 207 208 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 209 _thr_spinlock_init(); 210 _mutex_fork(curthread); 211 212 /* reinitalize library. */ 213 _libpthread_init(curthread); 214 215 /* Ready to continue, unblock signals. */ 216 _thr_signal_unblock(curthread); 217 218 /* Run down atfork child handlers. */ 219 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 220 if (af->child != NULL) 221 af->child(); 222 } 223 } else { 224 /* Parent process */ 225 errsave = errno; 226 227 #ifndef __DragonFly__ 228 if (unlock_malloc) 229 _spinunlock(__malloc_lock); 230 #endif 231 232 /* Ready to continue, unblock signals. */ 233 _thr_signal_unblock(curthread); 234 235 /* Run down atfork parent handlers. */ 236 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 237 if (af->parent != NULL) 238 af->parent(); 239 } 240 241 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 242 inprogress = 0; 243 if (waiters) 244 _thr_umtx_wake(&inprogress, waiters); 245 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 246 } 247 errno = errsave; 248 249 /* Return the process ID: */ 250 return (ret); 251 } 252 253 __strong_reference(_fork, fork); 254 __strong_reference(_pthread_atfork, pthread_atfork); 255 256