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 pthread_t curthread; 90 struct pthread_atfork *af; 91 92 af = __malloc(sizeof(struct pthread_atfork)); 93 if (af == NULL) 94 return (ENOMEM); 95 96 curthread = tls_get_curthread(); 97 af->prepare = prepare; 98 af->parent = parent; 99 af->child = child; 100 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 101 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 102 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 103 return (0); 104 } 105 106 /* 107 * Private at-fork used by the rtld and sem code, guaranteed to order 108 * after user fork handlers in prepare, and before user fork handlers 109 * in the post-fork parent and in the child. 110 * 111 * This is used to ensure no interference between internal and user 112 * fork handlers, in particular we do not want to lock-out rtld or 113 * semaphores before user fork handlers run, and we want to recover 114 * before any user post-fork handlers run. 115 */ 116 void 117 _thr_atfork_kern(void (*prepare)(void), void (*parent)(void), 118 void (*child)(void)) 119 { 120 pthread_t curthread; 121 struct pthread_atfork *af; 122 123 af = __malloc(sizeof(struct pthread_atfork)); 124 125 curthread = tls_get_curthread(); 126 af->prepare = prepare; 127 af->parent = parent; 128 af->child = child; 129 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 130 TAILQ_INSERT_TAIL(&_thr_atfork_kern_list, af, qe); 131 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 132 } 133 134 void 135 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info) 136 { 137 pthread_t curthread; 138 struct pthread_atfork *af, *af1; 139 140 curthread = tls_get_curthread(); 141 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 142 TAILQ_FOREACH_MUTABLE(af, &_thr_atfork_list, qe, af1) { 143 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 144 __elf_phdr_match_addr(phdr_info, af->parent) || 145 __elf_phdr_match_addr(phdr_info, af->child)) { 146 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 147 __free(af); 148 } 149 } 150 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 151 } 152 153 /* 154 * For a while, allow libpthread to work with a libc that doesn't 155 * export the malloc lock. 156 */ 157 #pragma weak __malloc_lock 158 159 pid_t _fork(void); 160 161 pid_t 162 _fork(void) 163 { 164 static umtx_t inprogress; 165 static int waiters; 166 umtx_t tmp; 167 168 pthread_t curthread; 169 struct pthread_atfork *af; 170 pid_t ret; 171 int errsave; 172 #ifndef __DragonFly__ 173 int unlock_malloc; 174 #endif 175 176 if (!_thr_is_inited()) 177 return (__syscall(SYS_fork)); 178 179 errsave = errno; 180 curthread = tls_get_curthread(); 181 182 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 183 tmp = inprogress; 184 while (tmp) { 185 waiters++; 186 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 187 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 188 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 189 waiters--; 190 tmp = inprogress; 191 } 192 inprogress = 1; 193 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 194 195 /* Run down atfork prepare handlers. */ 196 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 197 if (af->prepare != NULL) 198 af->prepare(); 199 } 200 201 #ifndef __DragonFly__ 202 /* 203 * Try our best to protect memory from being corrupted in 204 * child process because another thread in malloc code will 205 * simply be kill by fork(). 206 */ 207 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 208 unlock_malloc = 1; 209 _spinlock(__malloc_lock); 210 } else { 211 unlock_malloc = 0; 212 } 213 #endif 214 215 #ifdef _PTHREADS_DEBUGGING 216 _thr_log("fork-parent\n", 12); 217 #endif 218 219 _thr_signal_block(curthread); 220 221 /* 222 * Must be executed Just before the fork. 223 */ 224 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_kern_list, atfork_head, qe) { 225 if (af->prepare != NULL) 226 af->prepare(); 227 } 228 229 /* Fork a new process: */ 230 if ((ret = __syscall(SYS_fork)) == 0) { 231 /* 232 * Child process. 233 * 234 * NOTE: We are using the saved errno from above. Do not 235 * reload errno here. 236 */ 237 inprogress = 0; 238 239 /* 240 * Internal child fork handlers must be run immediately. 241 */ 242 TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { 243 if (af->child != NULL) 244 af->child(); 245 } 246 247 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 248 /* 249 * Thread list will be reinitialized, and later we call 250 * _libpthread_init(), it will add us back to list. 251 */ 252 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 253 254 /* child is a new kernel thread. */ 255 curthread->tid = _thr_get_tid(); 256 257 /* clear other threads locked us. */ 258 _thr_umtx_init(&curthread->lock); 259 _thr_umtx_init(&_thr_atfork_lock); 260 _thr_setthreaded(0); 261 262 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 263 _thr_spinlock_init(); 264 #ifdef _PTHREADS_DEBUGGING 265 _thr_log("fork-child\n", 11); 266 #endif 267 _mutex_fork(curthread, curthread->tid); 268 269 /* reinitalize library. */ 270 _libpthread_init(curthread); 271 272 /* Ready to continue, unblock signals. */ 273 _thr_signal_unblock(curthread); 274 275 /* Run down atfork child handlers. */ 276 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 277 if (af->child != NULL) 278 af->child(); 279 } 280 } else { 281 /* Parent process */ 282 errsave = errno; 283 284 #ifndef __DragonFly__ 285 if (unlock_malloc) 286 _spinunlock(__malloc_lock); 287 #endif 288 #ifdef _PTHREADS_DEBUGGING 289 _thr_log("fork-done\n", 10); 290 #endif 291 /* Run down atfork parent handlers. */ 292 TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { 293 if (af->parent != NULL) 294 af->parent(); 295 } 296 297 /* Ready to continue, unblock signals. */ 298 _thr_signal_unblock(curthread); 299 300 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 301 if (af->parent != NULL) 302 af->parent(); 303 } 304 305 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 306 inprogress = 0; 307 if (waiters) 308 _thr_umtx_wake(&inprogress, 0); 309 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 310 } 311 errno = errsave; 312 313 /* Return the process ID: */ 314 return (ret); 315 } 316 317 __strong_reference(_fork, fork); 318 __strong_reference(_pthread_atfork, pthread_atfork); 319