thr_fork.c revision 267200
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: stable/10/lib/libthr/thread/thr_fork.c 267200 2014-06-07 02:45:24Z kib $ 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 <errno.h> 63#include <link.h> 64#include <string.h> 65#include <stdlib.h> 66#include <unistd.h> 67#include <pthread.h> 68#include <spinlock.h> 69#include "un-namespace.h" 70 71#include "libc_private.h" 72#include "rtld_lock.h" 73#include "thr_private.h" 74 75__weak_reference(_pthread_atfork, pthread_atfork); 76 77int 78_pthread_atfork(void (*prepare)(void), void (*parent)(void), 79 void (*child)(void)) 80{ 81 struct pthread *curthread; 82 struct pthread_atfork *af; 83 84 _thr_check_init(); 85 86 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 87 return (ENOMEM); 88 89 curthread = _get_curthread(); 90 af->prepare = prepare; 91 af->parent = parent; 92 af->child = child; 93 THR_CRITICAL_ENTER(curthread); 94 _thr_rwl_wrlock(&_thr_atfork_lock); 95 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 96 _thr_rwl_unlock(&_thr_atfork_lock); 97 THR_CRITICAL_LEAVE(curthread); 98 return (0); 99} 100 101void 102__pthread_cxa_finalize(struct dl_phdr_info *phdr_info) 103{ 104 atfork_head temp_list = TAILQ_HEAD_INITIALIZER(temp_list); 105 struct pthread *curthread; 106 struct pthread_atfork *af, *af1; 107 108 _thr_check_init(); 109 110 curthread = _get_curthread(); 111 THR_CRITICAL_ENTER(curthread); 112 _thr_rwl_wrlock(&_thr_atfork_lock); 113 TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) { 114 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 115 __elf_phdr_match_addr(phdr_info, af->parent) || 116 __elf_phdr_match_addr(phdr_info, af->child)) { 117 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 118 TAILQ_INSERT_TAIL(&temp_list, af, qe); 119 } 120 } 121 _thr_rwl_unlock(&_thr_atfork_lock); 122 THR_CRITICAL_LEAVE(curthread); 123 while ((af = TAILQ_FIRST(&temp_list)) != NULL) { 124 TAILQ_REMOVE(&temp_list, af, qe); 125 free(af); 126 } 127 _thr_tsd_unload(phdr_info); 128 _thr_sigact_unload(phdr_info); 129} 130 131__weak_reference(_fork, fork); 132 133pid_t _fork(void); 134 135pid_t 136_fork(void) 137{ 138 struct pthread *curthread; 139 struct pthread_atfork *af; 140 pid_t ret; 141 int errsave, cancelsave; 142 int was_threaded; 143 int rtld_locks[MAX_RTLD_LOCKS]; 144 145 if (!_thr_is_inited()) 146 return (__sys_fork()); 147 148 curthread = _get_curthread(); 149 cancelsave = curthread->no_cancel; 150 curthread->no_cancel = 1; 151 _thr_rwl_rdlock(&_thr_atfork_lock); 152 153 /* Run down atfork prepare handlers. */ 154 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 155 if (af->prepare != NULL) 156 af->prepare(); 157 } 158 159 /* 160 * Block all signals until we reach a safe point. 161 */ 162 _thr_signal_block(curthread); 163 _thr_signal_prefork(); 164 165 /* 166 * All bets are off as to what should happen soon if the parent 167 * process was not so kindly as to set up pthread fork hooks to 168 * relinquish all running threads. 169 */ 170 if (_thr_isthreaded() != 0) { 171 was_threaded = 1; 172 _malloc_prefork(); 173 _rtld_atfork_pre(rtld_locks); 174 } else { 175 was_threaded = 0; 176 } 177 178 /* 179 * Fork a new process. 180 * There is no easy way to pre-resolve the __sys_fork symbol 181 * without performing the fork. Use the syscall(2) 182 * indirection, the syscall symbol is resolved in 183 * _thr_rtld_init() with side-effect free call. 184 */ 185 ret = syscall(SYS_fork); 186 if (ret == 0) { 187 /* Child process */ 188 errsave = errno; 189 curthread->cancel_pending = 0; 190 curthread->flags &= ~(THR_FLAGS_NEED_SUSPEND|THR_FLAGS_DETACHED); 191 192 /* 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; 197 198 /* child is a new kernel thread. */ 199 thr_self(&curthread->tid); 200 201 /* clear other threads locked us. */ 202 _thr_umutex_init(&curthread->lock); 203 _mutex_fork(curthread); 204 205 _thr_signal_postfork_child(); 206 207 if (was_threaded) 208 _rtld_atfork_post(rtld_locks); 209 _thr_setthreaded(0); 210 211 /* reinitalize library. */ 212 _libpthread_init(curthread); 213 214 /* atfork is reinitializeded by _libpthread_init()! */ 215 _thr_rwl_rdlock(&_thr_atfork_lock); 216 217 if (was_threaded) { 218 __isthreaded = 1; 219 _malloc_postfork(); 220 __isthreaded = 0; 221 } 222 223 /* Ready to continue, unblock signals. */ 224 _thr_signal_unblock(curthread); 225 226 /* Run down atfork child handlers. */ 227 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 228 if (af->child != NULL) 229 af->child(); 230 } 231 _thr_rwlock_unlock(&_thr_atfork_lock); 232 curthread->no_cancel = cancelsave; 233 } else { 234 /* Parent process */ 235 errsave = errno; 236 237 _thr_signal_postfork(); 238 239 if (was_threaded) { 240 _rtld_atfork_post(rtld_locks); 241 _malloc_postfork(); 242 } 243 244 /* Ready to continue, unblock signals. */ 245 _thr_signal_unblock(curthread); 246 247 /* Run down atfork parent handlers. */ 248 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 249 if (af->parent != NULL) 250 af->parent(); 251 } 252 253 _thr_rwlock_unlock(&_thr_atfork_lock); 254 curthread->no_cancel = cancelsave; 255 /* test async cancel */ 256 if (curthread->cancel_async) 257 _thr_testcancel(curthread); 258 } 259 errno = errsave; 260 261 return (ret); 262} 263