rthread_fork.c revision 1.4
1/* $OpenBSD: rthread_fork.c,v 1.4 2011/11/06 11:48:59 guenther 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#include <errno.h> 34#include <pthread.h> 35#include <stdlib.h> 36#include <unistd.h> 37 38#include "thread_private.h" /* in libc/include */ 39 40#include "rthread.h" 41 42struct rthread_atfork { 43 TAILQ_ENTRY(rthread_atfork) next; 44 void (*prepare)(void); 45 void (*parent)(void); 46 void (*child)(void); 47}; 48 49static TAILQ_HEAD(atfork_listhead, rthread_atfork) _atfork_list = 50 TAILQ_HEAD_INITIALIZER(_atfork_list); 51 52static _spinlock_lock_t _atfork_lock = _SPINLOCK_UNLOCKED; 53 54pid_t _thread_sys_fork(void); 55pid_t _thread_sys_vfork(void); 56pid_t _dofork(int); 57 58pid_t 59_dofork(int is_vfork) 60{ 61 pthread_t me; 62 pid_t (*sys_fork)(void); 63 pid_t newid; 64 65 sys_fork = is_vfork ? &_thread_sys_vfork : &_thread_sys_fork; 66 67 if (!_threads_ready) 68 return sys_fork(); 69 70 me = pthread_self(); 71 72 /* 73 * Protect important libc/ld.so critical areas across the fork call. 74 * dlclose() will grab the atexit lock via __cxa_finalize() so lock 75 * the dl_lock first. malloc()/free() can grab the arc4 lock so lock 76 * malloc_lock first. Finally lock the bind_lock last so that any lazy 77 * binding in the other locking functions can succeed. 78 */ 79 80#if defined(__ELF__) && defined(PIC) 81 _rthread_dl_lock(0); 82#endif 83 84 _thread_atexit_lock(); 85 _thread_malloc_lock(); 86 _thread_arc4_lock(); 87 88#if defined(__ELF__) && defined(PIC) 89 _rthread_bind_lock(0); 90#endif 91 92 newid = sys_fork(); 93 94#if defined(__ELF__) && defined(PIC) 95 _rthread_bind_lock(1); 96#endif 97 98 _thread_arc4_unlock(); 99 _thread_malloc_unlock(); 100 _thread_atexit_unlock(); 101 102#if defined(__ELF__) && defined(PIC) 103 _rthread_dl_lock(1); 104#endif 105 106 if (newid == 0) { 107 /* update this thread's structure */ 108 me->tid = getthrid(); 109 me->donesem.lock = _SPINLOCK_UNLOCKED; 110 me->flags &= ~THREAD_DETACHED; 111 me->flags_lock = _SPINLOCK_UNLOCKED; 112 113 /* this thread is the initial thread for the new process */ 114 _initial_thread = *me; 115 116 /* reinit the thread list */ 117 LIST_INIT(&_thread_list); 118 LIST_INSERT_HEAD(&_thread_list, &_initial_thread, threads); 119 _thread_lock = _SPINLOCK_UNLOCKED; 120 121 /* single threaded now */ 122 __isthreaded = 0; 123 } 124 return newid; 125} 126 127pid_t 128fork(void) 129{ 130 struct rthread_atfork *p; 131 pid_t newid; 132 133 _spinlock(&_atfork_lock); 134 TAILQ_FOREACH_REVERSE(p, &_atfork_list, atfork_listhead, next) 135 if (p->prepare) 136 p->prepare(); 137 newid = _dofork(0); 138 if (newid == 0) { 139 TAILQ_FOREACH(p, &_atfork_list, next) 140 if (p->child) 141 p->child(); 142 } else { 143 TAILQ_FOREACH(p, &_atfork_list, next) 144 if (p->parent) 145 p->parent(); 146 } 147 _spinunlock(&_atfork_lock); 148 return newid; 149} 150 151pid_t 152vfork(void) 153{ 154 return _dofork(1); 155} 156 157int 158pthread_atfork(void (*prepare)(void), void (*parent)(void), 159 void (*child)(void)) 160{ 161 struct rthread_atfork *af; 162 163 if ((af = malloc(sizeof *af)) == NULL) 164 return (ENOMEM); 165 166 af->prepare = prepare; 167 af->parent = parent; 168 af->child = child; 169 _spinlock(&_atfork_lock); 170 TAILQ_INSERT_TAIL(&_atfork_list, af, next); 171 _spinunlock(&_atfork_lock); 172 return (0); 173} 174