/* * Copyright (c) 2005 David Xu <davidxu@freebsd.org> * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Neither the name of the author nor the names of any co-contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD: head/lib/libthr/thread/thr_fork.c 213096 2010-08-23 $ */ /* * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the author nor the names of any co-contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * */ #include <sys/syscall.h> #include "namespace.h" #include <machine/tls.h> #include <errno.h> #include <link.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <pthread.h> #include <spinlock.h> #include <sys/file.h> #include "un-namespace.h" #include "libc_private.h" #include "thr_private.h" struct atfork_head _thr_atfork_list; struct atfork_head _thr_atfork_kern_list; umtx_t _thr_atfork_lock; /* * Execute a function in parent before and after the fork, and * in the child. */ int _pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void)) { pthread_t curthread; struct pthread_atfork *af; af = __malloc(sizeof(struct pthread_atfork)); if (af == NULL) return (ENOMEM); curthread = tls_get_curthread(); af->prepare = prepare; af->parent = parent; af->child = child; THR_UMTX_LOCK(curthread, &_thr_atfork_lock); TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe); THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); return (0); } /* * Private at-fork used by the rtld and sem code, guaranteed to order * after user fork handlers in prepare, and before user fork handlers * in the post-fork parent and in the child. * * This is used to ensure no interference between internal and user * fork handlers, in particular we do not want to lock-out rtld or * semaphores before user fork handlers run, and we want to recover * before any user post-fork handlers run. */ void _thr_atfork_kern(void (*prepare)(void), void (*parent)(void), void (*child)(void)) { pthread_t curthread; struct pthread_atfork *af; af = __malloc(sizeof(struct pthread_atfork)); curthread = tls_get_curthread(); af->prepare = prepare; af->parent = parent; af->child = child; THR_UMTX_LOCK(curthread, &_thr_atfork_lock); TAILQ_INSERT_TAIL(&_thr_atfork_kern_list, af, qe); THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); } void __pthread_cxa_finalize(struct dl_phdr_info *phdr_info) { pthread_t curthread; struct pthread_atfork *af, *af1; curthread = tls_get_curthread(); THR_UMTX_LOCK(curthread, &_thr_atfork_lock); TAILQ_FOREACH_MUTABLE(af, &_thr_atfork_list, qe, af1) { if (__elf_phdr_match_addr(phdr_info, af->prepare) || __elf_phdr_match_addr(phdr_info, af->parent) || __elf_phdr_match_addr(phdr_info, af->child)) { TAILQ_REMOVE(&_thr_atfork_list, af, qe); __free(af); } } THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); } /* * For a while, allow libpthread to work with a libc that doesn't * export the malloc lock. */ #pragma weak __malloc_lock pid_t _fork(void); pid_t _fork(void) { static umtx_t inprogress; static int waiters; umtx_t tmp; pthread_t curthread; struct pthread_atfork *af; pid_t ret; int errsave; #ifndef __DragonFly__ int unlock_malloc; #endif if (!_thr_is_inited()) return (__syscall(SYS_fork)); errsave = errno; curthread = tls_get_curthread(); THR_UMTX_LOCK(curthread, &_thr_atfork_lock); tmp = inprogress; while (tmp) { waiters++; THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); _thr_umtx_wait(&inprogress, tmp, NULL, 0); THR_UMTX_LOCK(curthread, &_thr_atfork_lock); waiters--; tmp = inprogress; } inprogress = 1; THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); /* Run down atfork prepare handlers. */ TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) { if (af->prepare != NULL) af->prepare(); } #ifndef __DragonFly__ /* * Try our best to protect memory from being corrupted in * child process because another thread in malloc code will * simply be kill by fork(). */ if ((_thr_isthreaded() != 0) && (__malloc_lock != NULL)) { unlock_malloc = 1; _spinlock(__malloc_lock); } else { unlock_malloc = 0; } #endif #ifdef _PTHREADS_DEBUGGING _thr_log("fork-parent\n", 12); #endif _thr_signal_block(curthread); /* * Must be executed Just before the fork. */ TAILQ_FOREACH_REVERSE(af, &_thr_atfork_kern_list, atfork_head, qe) { if (af->prepare != NULL) af->prepare(); } /* Fork a new process: */ if ((ret = __syscall(SYS_fork)) == 0) { /* * Child process. * * NOTE: We are using the saved errno from above. Do not * reload errno here. */ inprogress = 0; /* * Internal child fork handlers must be run immediately. */ TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { if (af->child != NULL) af->child(); } curthread->cancelflags &= ~THR_CANCEL_NEEDED; /* * Thread list will be reinitialized, and later we call * _libpthread_init(), it will add us back to list. */ curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED); /* child is a new kernel thread. */ curthread->tid = _thr_get_tid(); /* clear other threads locked us. */ _thr_umtx_init(&curthread->lock); _thr_umtx_init(&_thr_atfork_lock); _thr_setthreaded(0); /* reinitialize libc spinlocks, this includes __malloc_lock. */ _thr_spinlock_init(); #ifdef _PTHREADS_DEBUGGING _thr_log("fork-child\n", 11); #endif _mutex_fork(curthread, curthread->tid); /* reinitalize library. */ _libpthread_init(curthread); /* Ready to continue, unblock signals. */ _thr_signal_unblock(curthread); /* Run down atfork child handlers. */ TAILQ_FOREACH(af, &_thr_atfork_list, qe) { if (af->child != NULL) af->child(); } } else { /* Parent process */ errsave = errno; #ifndef __DragonFly__ if (unlock_malloc) _spinunlock(__malloc_lock); #endif #ifdef _PTHREADS_DEBUGGING _thr_log("fork-done\n", 10); #endif /* Run down atfork parent handlers. */ TAILQ_FOREACH(af, &_thr_atfork_kern_list, qe) { if (af->parent != NULL) af->parent(); } /* Ready to continue, unblock signals. */ _thr_signal_unblock(curthread); TAILQ_FOREACH(af, &_thr_atfork_list, qe) { if (af->parent != NULL) af->parent(); } THR_UMTX_LOCK(curthread, &_thr_atfork_lock); inprogress = 0; if (waiters) _thr_umtx_wake(&inprogress, 0); THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); } errno = errsave; /* Return the process ID: */ return (ret); } __strong_reference(_fork, fork); __strong_reference(_pthread_atfork, pthread_atfork);
