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 <sys/syscall.h> 62 63 #include <machine/tls.h> 64 65 #include <errno.h> 66 #include <link.h> 67 #include <string.h> 68 #include <stdlib.h> 69 #include <unistd.h> 70 #include <fcntl.h> 71 #include <pthread.h> 72 #include <spinlock.h> 73 #include "un-namespace.h" 74 75 #include "libc_private.h" 76 #include "thr_private.h" 77 78 struct atfork_head _thr_atfork_list; 79 umtx_t _thr_atfork_lock; 80 81 int 82 _pthread_atfork(void (*prepare)(void), void (*parent)(void), 83 void (*child)(void)) 84 { 85 struct pthread *curthread; 86 struct pthread_atfork *af; 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 curthread = tls_get_curthread(); 108 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 109 TAILQ_FOREACH_MUTABLE(af, &_thr_atfork_list, qe, af1) { 110 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 111 __elf_phdr_match_addr(phdr_info, af->parent) || 112 __elf_phdr_match_addr(phdr_info, af->child)) { 113 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 114 free(af); 115 } 116 } 117 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 118 } 119 120 /* 121 * For a while, allow libpthread to work with a libc that doesn't 122 * export the malloc lock. 123 */ 124 #pragma weak __malloc_lock 125 126 pid_t _fork(void); 127 128 pid_t 129 _fork(void) 130 { 131 static umtx_t inprogress; 132 static int waiters; 133 umtx_t tmp; 134 135 struct pthread *curthread; 136 struct pthread_atfork *af; 137 pid_t ret; 138 int errsave; 139 #ifndef __DragonFly__ 140 int unlock_malloc; 141 #endif 142 143 if (!_thr_is_inited()) 144 return (__syscall(SYS_fork)); 145 146 curthread = tls_get_curthread(); 147 148 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 149 tmp = inprogress; 150 while (tmp) { 151 waiters++; 152 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 153 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 154 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 155 waiters--; 156 tmp = inprogress; 157 } 158 inprogress = 1; 159 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 160 161 /* Run down atfork prepare handlers. */ 162 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 163 if (af->prepare != NULL) 164 af->prepare(); 165 } 166 167 #ifndef __DragonFly__ 168 /* 169 * Try our best to protect memory from being corrupted in 170 * child process because another thread in malloc code will 171 * simply be kill by fork(). 172 */ 173 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 174 unlock_malloc = 1; 175 _spinlock(__malloc_lock); 176 } else { 177 unlock_malloc = 0; 178 } 179 #endif 180 181 /* 182 * Block all signals until we reach a safe point. 183 */ 184 _thr_signal_block(curthread); 185 186 /* Fork a new process: */ 187 if ((ret = __syscall(SYS_fork)) == 0) { 188 /* Child process */ 189 errsave = errno; 190 inprogress = 0; 191 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 192 /* 193 * Thread list will be reinitialized, and later we call 194 * _libpthread_init(), it will add us back to list. 195 */ 196 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 197 198 /* child is a new kernel thread. */ 199 curthread->tid = _thr_get_tid(); 200 201 /* clear other threads locked us. */ 202 _thr_umtx_init(&curthread->lock); 203 _thr_umtx_init(&_thr_atfork_lock); 204 _thr_setthreaded(0); 205 206 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 207 _thr_spinlock_init(); 208 _mutex_fork(curthread); 209 210 /* reinitalize library. */ 211 _libpthread_init(curthread); 212 213 /* Ready to continue, unblock signals. */ 214 _thr_signal_unblock(curthread); 215 216 /* Run down atfork child handlers. */ 217 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 218 if (af->child != NULL) 219 af->child(); 220 } 221 } else { 222 /* Parent process */ 223 errsave = errno; 224 225 #ifndef __DragonFly__ 226 if (unlock_malloc) 227 _spinunlock(__malloc_lock); 228 #endif 229 230 /* Ready to continue, unblock signals. */ 231 _thr_signal_unblock(curthread); 232 233 /* Run down atfork parent handlers. */ 234 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 235 if (af->parent != NULL) 236 af->parent(); 237 } 238 239 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 240 inprogress = 0; 241 if (waiters) 242 _thr_umtx_wake(&inprogress, waiters); 243 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 244 } 245 errno = errsave; 246 247 /* Return the process ID: */ 248 return (ret); 249 } 250 251 __strong_reference(_fork, fork); 252 __strong_reference(_pthread_atfork, pthread_atfork); 253 254