diff options
Diffstat (limited to 'lib/libthr/thread/thr_fork.c')
| -rw-r--r-- | lib/libthr/thread/thr_fork.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_fork.c b/lib/libthr/thread/thr_fork.c new file mode 100644 index 0000000..8b311cb --- /dev/null +++ b/lib/libthr/thread/thr_fork.c @@ -0,0 +1,222 @@ +/* + * 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. + * + * $FreeBSD$ + */ + +/* + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by John Birrell. + * 4. 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 <errno.h> +#include <string.h> +#include <stdlib.h> +#include <unistd.h> +#include <pthread.h> +#include <spinlock.h> + +#include "libc_private.h" +#include "thr_private.h" + +__weak_reference(_pthread_atfork, pthread_atfork); + +int +_pthread_atfork(void (*prepare)(void), void (*parent)(void), + void (*child)(void)) +{ + struct pthread *curthread; + struct pthread_atfork *af; + + _thr_check_init(); + + if ((af = malloc(sizeof(struct pthread_atfork))) == NULL) + return (ENOMEM); + + curthread = _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); +} + +/* + * For a while, allow libpthread to work with a libc that doesn't + * export the malloc lock. + */ +#pragma weak __malloc_lock + +__weak_reference(_fork, fork); + +pid_t +_fork(void) +{ + static umtx_t inprogress; + static int waiters; + umtx_t tmp; + + struct pthread *curthread; + struct pthread_atfork *af; + pid_t ret; + int errsave; + int unlock_malloc; + + if (!_thr_is_inited()) + return (__sys_fork()); + + curthread = _get_curthread(); + + /* + * Block all signals until we reach a safe point. + */ + _thr_signal_block(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); + THR_UMTX_LOCK(curthread, &_thr_atfork_lock); + waiters--; + tmp = inprogress; + } + inprogress = 1; + + /* Unlock mutex, allow new hook to be added during executing hooks. */ + 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(); + } + + /* + * 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; + } + + /* Fork a new process: */ + if ((ret = __sys_fork()) == 0) { + /* Child process */ + errsave = errno; + inprogress = 0; + 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. */ + thr_self(&curthread->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(); + _mutex_fork(curthread); + + /* 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; + + if (unlock_malloc) + _spinunlock(__malloc_lock); + + /* Ready to continue, unblock signals. */ + _thr_signal_unblock(curthread); + + /* Run down atfork parent handlers. */ + 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, waiters); + THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock); + } + errno = errsave; + + /* Return the process ID: */ + return (ret); +} |
