| 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); |