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 <sys/syscall.h> 61 #include "namespace.h" 62 #include <machine/tls.h> 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 struct atfork_head _thr_atfork_kern_list; 78 umtx_t _thr_atfork_lock; 79 80 /* 81 * Execute a function in parent before and after the fork, and 82 * in the child. 83 */ 84 int 85 _pthread_atfork(void (*prepare)(void), void (*parent)(void), 86 void (*child)(void)) 87 { 88 struct pthread *curthread; 89 struct pthread_atfork *af; 90 91 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 92 return (ENOMEM); 93 94 curthread = tls_get_curthread(); 95 af->prepare = prepare; 96 af->parent = parent; 97 af->child = child; 98 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 99 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 100 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 101 return (0); 102 } 103 104 /* 105 * Private at-fork used by the rtld and sem code, guaranteed to order 106 * after user fork handlers in prepare, and before user fork handlers 107 * in the post-fork parent and in the child. 108 * 109 * This is used to ensure no interference between internal and user 110 * fork handlers, in particular we do not want to lock-out rtld or 111 * semaphores before user fork handlers run, and we want to recover 112 * before any user post-fork handlers run. 113 */ 114 void 115 _thr_atfork_kern(void (*prepare)(void), void (*parent)(void), 116 void (*child)(void)) 117 { 118 struct pthread *curthread; 119 struct pthread_atfork *af; 120 121 af = malloc(sizeof(struct pthread_atfork)); 122 123 curthread = tls_get_curthread(); 124 af->prepare = prepare; 125 af->parent = parent; 126 af->child = child; 127 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 128 TAILQ_INSERT_TAIL(&_thr_atfork_kern_list, af, qe); 129 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 130 } 131 132 void 133 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info) 134 { 135 struct pthread *curthread; 136 struct pthread_atfork *af, *af1; 137 138 curthread = tls_get_curthread(); 139 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 140 TAILQ_FOREACH_MUTABLE(af, &_thr_atfork_list, qe, af1) { 141 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 142 __elf_phdr_match_addr(phdr_info, af->parent) || 143 __elf_phdr_match_addr(phdr_info, af->child)) { 144 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 145 free(af); 146 } 147 } 148 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 149 } 150 151 /* 152 * For a while, allow libpthread to work with a libc that doesn't 153 * export the malloc lock. 154 */ 155 #pragma weak __malloc_lock 156 157 pid_t _fork(void); 158 159 pid_t 160 _fork(void) 161 { 162 static umtx_t inprogress; 163 static int waiters; 164 umtx_t tmp; 165 166 struct pthread *curthread; 167 struct pthread_atfork *af; 168 pid_t ret; 169 int errsave; 170 #ifndef __DragonFly__ 171 int unlock_malloc; 172 #endif 173 174 if (!_thr_is_inited()) 175 return (__syscall(SYS_fork)); 176 177 curthread = tls_get_curthread(); 178 179 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 180 tmp = inprogress; 181 while (tmp) { 182 waiters++; 183 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 184 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 185 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 186 waiters--; 187 tmp = inprogress; 188 } 189 inprogress = 1; 190 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 191 192 /* Run down atfork prepare handlers. */ 193 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 194 if (af->prepare != NULL) 195 af->prepare(); 196 } 197 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_kern_list, atfork_head, qe) { 198 if (af->prepare != NULL) 199 af->prepare(); 200 } 201 202 #ifndef __DragonFly__ 203 /* 204 * Try our best to protect memory from being corrupted in 205 * child process because another thread in malloc code will 206 * simply be kill by fork(). 207 */ 208 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 209 unlock_malloc = 1; 210 _spinlock(__malloc_lock); 211 } else { 212 unlock_malloc = 0; 213 } 214 #endif 215 216 /* 217 * Block all signals until we reach a safe point. 218 */ 219 _thr_signal_block(curthread); 220 #ifdef _PTHREADS_DEBUGGING 221 _thr_log("fork-parent\n", 12); 222 #endif 223 224 /* Fork a new process: */ 225 if ((ret = __syscall(SYS_fork)) == 0) { 226 /* Child process */ 227 errsave = errno; 228 inprogress = 0; 229 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 230 /* 231 * Thread list will be reinitialized, and later we call 232 * _libpthread_init(), it will add us back to list. 233 */ 234 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 235 236 /* child is a new kernel thread. */ 237 curthread->tid = _thr_get_tid(); 238 239 /* clear other threads locked us. */ 240 _thr_umtx_init(&curthread->lock); 241 _thr_umtx_init(&_thr_atfork_lock); 242 _thr_setthreaded(0); 243 244 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 245 _thr_spinlock_init(); 246 #ifdef _PTHREADS_DEBUGGING 247 _thr_log("fork-child\n", 11); 248 #endif 249 _mutex_fork(curthread); 250 251 /* reinitalize library. */ 252 _libpthread_init(curthread); 253 254 /* Ready to continue, unblock signals. */ 255 _thr_signal_unblock(curthread); 256 257 /* Run down atfork child handlers. */ 258 TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { 259 if (af->child != NULL) 260 af->child(); 261 } 262 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 263 if (af->child != NULL) 264 af->child(); 265 } 266 } else { 267 /* Parent process */ 268 errsave = errno; 269 270 #ifndef __DragonFly__ 271 if (unlock_malloc) 272 _spinunlock(__malloc_lock); 273 #endif 274 #ifdef _PTHREADS_DEBUGGING 275 _thr_log("fork-done\n", 10); 276 #endif 277 /* Ready to continue, unblock signals. */ 278 _thr_signal_unblock(curthread); 279 280 /* Run down atfork parent handlers. */ 281 TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { 282 if (af->parent != NULL) 283 af->parent(); 284 } 285 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 286 if (af->parent != NULL) 287 af->parent(); 288 } 289 290 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 291 inprogress = 0; 292 if (waiters) 293 _thr_umtx_wake(&inprogress, waiters); 294 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 295 } 296 errno = errsave; 297 298 /* Return the process ID: */ 299 return (ret); 300 } 301 302 __strong_reference(_fork, fork); 303 __strong_reference(_pthread_atfork, pthread_atfork); 304