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 <sys/file.h> 72 #include "un-namespace.h" 73 74 #include "libc_private.h" 75 #include "thr_private.h" 76 77 struct atfork_head _thr_atfork_list; 78 struct atfork_head _thr_atfork_kern_list; 79 umtx_t _thr_atfork_lock; 80 81 /* 82 * Execute a function in parent before and after the fork, and 83 * in the child. 84 */ 85 int 86 _pthread_atfork(void (*prepare)(void), void (*parent)(void), 87 void (*child)(void)) 88 { 89 struct pthread *curthread; 90 struct pthread_atfork *af; 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 * Private at-fork used by the rtld and sem code, guaranteed to order 107 * after user fork handlers in prepare, and before user fork handlers 108 * in the post-fork parent and in the child. 109 * 110 * This is used to ensure no interference between internal and user 111 * fork handlers, in particular we do not want to lock-out rtld or 112 * semaphores before user fork handlers run, and we want to recover 113 * before any user post-fork handlers run. 114 */ 115 void 116 _thr_atfork_kern(void (*prepare)(void), void (*parent)(void), 117 void (*child)(void)) 118 { 119 struct pthread *curthread; 120 struct pthread_atfork *af; 121 122 af = malloc(sizeof(struct pthread_atfork)); 123 124 curthread = tls_get_curthread(); 125 af->prepare = prepare; 126 af->parent = parent; 127 af->child = child; 128 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 129 TAILQ_INSERT_TAIL(&_thr_atfork_kern_list, af, qe); 130 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 131 } 132 133 void 134 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info) 135 { 136 struct pthread *curthread; 137 struct pthread_atfork *af, *af1; 138 139 curthread = tls_get_curthread(); 140 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 141 TAILQ_FOREACH_MUTABLE(af, &_thr_atfork_list, qe, af1) { 142 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 143 __elf_phdr_match_addr(phdr_info, af->parent) || 144 __elf_phdr_match_addr(phdr_info, af->child)) { 145 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 146 free(af); 147 } 148 } 149 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 150 } 151 152 /* 153 * For a while, allow libpthread to work with a libc that doesn't 154 * export the malloc lock. 155 */ 156 #pragma weak __malloc_lock 157 158 pid_t _fork(void); 159 160 pid_t 161 _fork(void) 162 { 163 static umtx_t inprogress; 164 static int waiters; 165 umtx_t tmp; 166 167 struct pthread *curthread; 168 struct pthread_atfork *af; 169 pid_t ret; 170 int errsave; 171 #ifndef __DragonFly__ 172 int unlock_malloc; 173 #endif 174 175 if (!_thr_is_inited()) 176 return (__syscall(SYS_fork)); 177 178 errsave = errno; 179 curthread = tls_get_curthread(); 180 181 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 182 tmp = inprogress; 183 while (tmp) { 184 waiters++; 185 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 186 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 187 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 188 waiters--; 189 tmp = inprogress; 190 } 191 inprogress = 1; 192 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 193 194 /* Run down atfork prepare handlers. */ 195 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 196 if (af->prepare != NULL) 197 af->prepare(); 198 } 199 200 #ifndef __DragonFly__ 201 /* 202 * Try our best to protect memory from being corrupted in 203 * child process because another thread in malloc code will 204 * simply be kill by fork(). 205 */ 206 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 207 unlock_malloc = 1; 208 _spinlock(__malloc_lock); 209 } else { 210 unlock_malloc = 0; 211 } 212 #endif 213 214 #ifdef _PTHREADS_DEBUGGING 215 _thr_log("fork-parent\n", 12); 216 #endif 217 218 _thr_signal_block(curthread); 219 220 /* 221 * Must be executed Just before the fork. 222 */ 223 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_kern_list, atfork_head, qe) { 224 if (af->prepare != NULL) 225 af->prepare(); 226 } 227 228 /* Fork a new process: */ 229 if ((ret = __syscall(SYS_fork)) == 0) { 230 /* 231 * Child process. 232 * 233 * NOTE: We are using the saved errno from above. Do not 234 * reload errno here. 235 */ 236 inprogress = 0; 237 238 /* 239 * Internal child fork handlers must be run immediately. 240 */ 241 TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { 242 if (af->child != NULL) 243 af->child(); 244 } 245 246 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 247 /* 248 * Thread list will be reinitialized, and later we call 249 * _libpthread_init(), it will add us back to list. 250 */ 251 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 252 253 /* child is a new kernel thread. */ 254 curthread->tid = _thr_get_tid(); 255 256 /* clear other threads locked us. */ 257 _thr_umtx_init(&curthread->lock); 258 _thr_umtx_init(&_thr_atfork_lock); 259 _thr_setthreaded(0); 260 261 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 262 _thr_spinlock_init(); 263 #ifdef _PTHREADS_DEBUGGING 264 _thr_log("fork-child\n", 11); 265 #endif 266 _mutex_fork(curthread); 267 268 /* reinitalize library. */ 269 _libpthread_init(curthread); 270 271 /* Ready to continue, unblock signals. */ 272 _thr_signal_unblock(curthread); 273 274 /* Run down atfork child handlers. */ 275 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 276 if (af->child != NULL) 277 af->child(); 278 } 279 } else { 280 /* Parent process */ 281 errsave = errno; 282 283 #ifndef __DragonFly__ 284 if (unlock_malloc) 285 _spinunlock(__malloc_lock); 286 #endif 287 #ifdef _PTHREADS_DEBUGGING 288 _thr_log("fork-done\n", 10); 289 #endif 290 /* Run down atfork parent handlers. */ 291 TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { 292 if (af->parent != NULL) 293 af->parent(); 294 } 295 296 /* Ready to continue, unblock signals. */ 297 _thr_signal_unblock(curthread); 298 299 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 300 if (af->parent != NULL) 301 af->parent(); 302 } 303 304 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 305 inprogress = 0; 306 if (waiters) 307 _thr_umtx_wake(&inprogress, 0); 308 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 309 } 310 errno = errsave; 311 312 /* Return the process ID: */ 313 return (ret); 314 } 315 316 __strong_reference(_fork, fork); 317 __strong_reference(_pthread_atfork, pthread_atfork); 318