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 umtx_t _thr_atfork_lock; 78 79 int 80 _pthread_atfork(void (*prepare)(void), void (*parent)(void), 81 void (*child)(void)) 82 { 83 struct pthread *curthread; 84 struct pthread_atfork *af; 85 86 if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) 87 return (ENOMEM); 88 89 curthread = tls_get_curthread(); 90 af->prepare = prepare; 91 af->parent = parent; 92 af->child = child; 93 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 94 TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); 95 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 96 return (0); 97 } 98 99 void 100 __pthread_cxa_finalize(struct dl_phdr_info *phdr_info) 101 { 102 struct pthread *curthread; 103 struct pthread_atfork *af, *af1; 104 105 curthread = tls_get_curthread(); 106 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 107 TAILQ_FOREACH_MUTABLE(af, &_thr_atfork_list, qe, af1) { 108 if (__elf_phdr_match_addr(phdr_info, af->prepare) || 109 __elf_phdr_match_addr(phdr_info, af->parent) || 110 __elf_phdr_match_addr(phdr_info, af->child)) { 111 TAILQ_REMOVE(&_thr_atfork_list, af, qe); 112 free(af); 113 } 114 } 115 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 116 } 117 118 /* 119 * For a while, allow libpthread to work with a libc that doesn't 120 * export the malloc lock. 121 */ 122 #pragma weak __malloc_lock 123 124 pid_t _fork(void); 125 126 pid_t 127 _fork(void) 128 { 129 static umtx_t inprogress; 130 static int waiters; 131 umtx_t tmp; 132 133 struct pthread *curthread; 134 struct pthread_atfork *af; 135 pid_t ret; 136 int errsave; 137 #ifndef __DragonFly__ 138 int unlock_malloc; 139 #endif 140 141 if (!_thr_is_inited()) 142 return (__syscall(SYS_fork)); 143 144 curthread = tls_get_curthread(); 145 146 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 147 tmp = inprogress; 148 while (tmp) { 149 waiters++; 150 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 151 _thr_umtx_wait(&inprogress, tmp, NULL, 0); 152 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 153 waiters--; 154 tmp = inprogress; 155 } 156 inprogress = 1; 157 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 158 159 /* Run down atfork prepare handlers. */ 160 TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { 161 if (af->prepare != NULL) 162 af->prepare(); 163 } 164 165 #ifndef __DragonFly__ 166 /* 167 * Try our best to protect memory from being corrupted in 168 * child process because another thread in malloc code will 169 * simply be kill by fork(). 170 */ 171 if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { 172 unlock_malloc = 1; 173 _spinlock(__malloc_lock); 174 } else { 175 unlock_malloc = 0; 176 } 177 #endif 178 179 /* 180 * Block all signals until we reach a safe point. 181 */ 182 _thr_signal_block(curthread); 183 184 /* Fork a new process: */ 185 if ((ret = __syscall(SYS_fork)) == 0) { 186 /* Child process */ 187 errsave = errno; 188 inprogress = 0; 189 curthread->cancelflags &= ~THR_CANCEL_NEEDED; 190 /* 191 * Thread list will be reinitialized, and later we call 192 * _libpthread_init(), it will add us back to list. 193 */ 194 curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); 195 196 /* child is a new kernel thread. */ 197 curthread->tid = _thr_get_tid(); 198 199 /* clear other threads locked us. */ 200 _thr_umtx_init(&curthread->lock); 201 _thr_umtx_init(&_thr_atfork_lock); 202 _thr_setthreaded(0); 203 204 /* reinitialize libc spinlocks, this includes __malloc_lock. */ 205 _thr_spinlock_init(); 206 _mutex_fork(curthread); 207 208 /* reinitalize library. */ 209 _libpthread_init(curthread); 210 211 /* Ready to continue, unblock signals. */ 212 _thr_signal_unblock(curthread); 213 214 /* Run down atfork child handlers. */ 215 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 216 if (af->child != NULL) 217 af->child(); 218 } 219 } else { 220 /* Parent process */ 221 errsave = errno; 222 223 #ifndef __DragonFly__ 224 if (unlock_malloc) 225 _spinunlock(__malloc_lock); 226 #endif 227 228 /* Ready to continue, unblock signals. */ 229 _thr_signal_unblock(curthread); 230 231 /* Run down atfork parent handlers. */ 232 TAILQ_FOREACH(af, &_thr_atfork_list, qe) { 233 if (af->parent != NULL) 234 af->parent(); 235 } 236 237 THR_UMTX_LOCK(curthread, &_thr_atfork_lock); 238 inprogress = 0; 239 if (waiters) 240 _thr_umtx_wake(&inprogress, waiters); 241 THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); 242 } 243 errno = errsave; 244 245 /* Return the process ID: */ 246 return (ret); 247 } 248 249 __strong_reference(_fork, fork); 250 __strong_reference(_pthread_atfork, pthread_atfork); 251