1 /* $OpenBSD: rthread_fork.c,v 1.6 2012/08/22 23:43:32 matthew Exp $ */ 2 3 /* 4 * Copyright (c) 2008 Kurt Miller <kurt@openbsd.org> 5 * Copyright (c) 2008 Philip Guenther <guenther@gmail.com> 6 * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org> 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Neither the name of the author nor the names of any co-contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 * $FreeBSD: /repoman/r/ncvs/src/lib/libc_r/uthread/uthread_atfork.c,v 1.1 2004/12/10 03:36:45 grog Exp $ 31 */ 32 33 #if defined(__ELF__) 34 #include <sys/types.h> 35 #include <sys/exec_elf.h> 36 #pragma weak _DYNAMIC 37 #endif 38 39 #include <errno.h> 40 #include <pthread.h> 41 #include <stdlib.h> 42 #include <unistd.h> 43 44 #include "thread_private.h" /* in libc/include */ 45 46 #include "rthread.h" 47 48 struct rthread_atfork { 49 TAILQ_ENTRY(rthread_atfork) next; 50 void (*prepare)(void); 51 void (*parent)(void); 52 void (*child)(void); 53 }; 54 55 static TAILQ_HEAD(atfork_listhead, rthread_atfork) _atfork_list = 56 TAILQ_HEAD_INITIALIZER(_atfork_list); 57 58 static _spinlock_lock_t _atfork_lock = _SPINLOCK_UNLOCKED; 59 60 pid_t _thread_sys_fork(void); 61 pid_t _thread_sys_vfork(void); 62 pid_t _dofork(int); 63 64 pid_t 65 _dofork(int is_vfork) 66 { 67 pthread_t me; 68 pid_t (*sys_fork)(void); 69 pid_t newid; 70 71 sys_fork = is_vfork ? &_thread_sys_vfork : &_thread_sys_fork; 72 73 if (!_threads_ready) 74 return sys_fork(); 75 76 me = pthread_self(); 77 78 /* 79 * Protect important libc/ld.so critical areas across the fork call. 80 * dlclose() will grab the atexit lock via __cxa_finalize() so lock 81 * the dl_lock first. malloc()/free() can grab the arc4 lock so lock 82 * malloc_lock first. Finally lock the bind_lock last so that any lazy 83 * binding in the other locking functions can succeed. 84 */ 85 86 #if defined(__ELF__) 87 if (_DYNAMIC) 88 _rthread_dl_lock(0); 89 #endif 90 91 _thread_atexit_lock(); 92 _thread_malloc_lock(); 93 _thread_arc4_lock(); 94 95 #if defined(__ELF__) 96 if (_DYNAMIC) 97 _rthread_bind_lock(0); 98 #endif 99 100 newid = sys_fork(); 101 102 #if defined(__ELF__) 103 if (_DYNAMIC) 104 _rthread_bind_lock(1); 105 #endif 106 107 _thread_arc4_unlock(); 108 _thread_malloc_unlock(); 109 _thread_atexit_unlock(); 110 111 #if defined(__ELF__) 112 if (_DYNAMIC) 113 _rthread_dl_lock(1); 114 #endif 115 116 if (newid == 0) { 117 /* update this thread's structure */ 118 me->tid = getthrid(); 119 me->donesem.lock = _SPINLOCK_UNLOCKED; 120 me->flags &= ~THREAD_DETACHED; 121 me->flags_lock = _SPINLOCK_UNLOCKED; 122 123 /* this thread is the initial thread for the new process */ 124 _initial_thread = *me; 125 126 /* reinit the thread list */ 127 LIST_INIT(&_thread_list); 128 LIST_INSERT_HEAD(&_thread_list, &_initial_thread, threads); 129 _thread_lock = _SPINLOCK_UNLOCKED; 130 131 /* single threaded now */ 132 __isthreaded = 0; 133 } 134 return newid; 135 } 136 137 pid_t 138 fork(void) 139 { 140 struct rthread_atfork *p; 141 pid_t newid; 142 143 _spinlock(&_atfork_lock); 144 TAILQ_FOREACH_REVERSE(p, &_atfork_list, atfork_listhead, next) 145 if (p->prepare) 146 p->prepare(); 147 newid = _dofork(0); 148 if (newid == 0) { 149 TAILQ_FOREACH(p, &_atfork_list, next) 150 if (p->child) 151 p->child(); 152 } else { 153 TAILQ_FOREACH(p, &_atfork_list, next) 154 if (p->parent) 155 p->parent(); 156 } 157 _spinunlock(&_atfork_lock); 158 return newid; 159 } 160 161 pid_t 162 vfork(void) 163 { 164 return _dofork(1); 165 } 166 167 int 168 pthread_atfork(void (*prepare)(void), void (*parent)(void), 169 void (*child)(void)) 170 { 171 struct rthread_atfork *af; 172 173 if ((af = malloc(sizeof *af)) == NULL) 174 return (ENOMEM); 175 176 af->prepare = prepare; 177 af->parent = parent; 178 af->child = child; 179 _spinlock(&_atfork_lock); 180 TAILQ_INSERT_TAIL(&_atfork_list, af, next); 181 _spinunlock(&_atfork_lock); 182 return (0); 183 } 184