02c3c85869
some cases we want to improve:
1) if a thread signal got a signal while in cancellation point,
it is possible the TDP_WAKEUP may be eaten by signal handler
if the handler called some interruptibly system calls.
2) In signal handler, we want to disable cancellation.
3) When thread holding some low level locks, it is better to
disable signal, those code need not to worry reentrancy,
sigprocmask system call is avoided because it is a bit expensive.
The signal handler wrapper works in this way:
1) libthr installs its signal handler if user code invokes sigaction
to install its handler, the user handler is recorded in internal
array.
2) when a signal is delivered, libthr's signal handler is invoke,
libthr checks if thread holds some low level lock or is in critical
region, if it is true, the signal is buffered, and all signals are
masked, once the thread leaves critical region, correct signal
mask is restored and buffered signal is processed.
3) before user signal handler is invoked, cancellation is temporarily
disabled, after user signal handler is returned, cancellation state
is restored, and pending cancellation is rescheduled.
241 lines
6.8 KiB
C
241 lines
6.8 KiB
C
/*
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* Copyright (c) 2005 David Xu <davidxu@freebsd.org>
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* Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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#include "namespace.h"
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#include <errno.h>
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#include <link.h>
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#include <string.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <pthread.h>
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#include <spinlock.h>
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#include "un-namespace.h"
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#include "libc_private.h"
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#include "rtld_lock.h"
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#include "thr_private.h"
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__weak_reference(_pthread_atfork, pthread_atfork);
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int
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_pthread_atfork(void (*prepare)(void), void (*parent)(void),
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void (*child)(void))
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{
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struct pthread *curthread;
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struct pthread_atfork *af;
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_thr_check_init();
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if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
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return (ENOMEM);
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curthread = _get_curthread();
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af->prepare = prepare;
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af->parent = parent;
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af->child = child;
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THR_UMUTEX_LOCK(curthread, &_thr_atfork_lock);
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TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
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THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
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return (0);
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}
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void
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__pthread_cxa_finalize(struct dl_phdr_info *phdr_info)
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{
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struct pthread *curthread;
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struct pthread_atfork *af, *af1;
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_thr_check_init();
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curthread = _get_curthread();
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THR_UMUTEX_LOCK(curthread, &_thr_atfork_lock);
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TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) {
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if (__elf_phdr_match_addr(phdr_info, af->prepare) ||
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__elf_phdr_match_addr(phdr_info, af->parent) ||
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__elf_phdr_match_addr(phdr_info, af->child)) {
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TAILQ_REMOVE(&_thr_atfork_list, af, qe);
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free(af);
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}
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}
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THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
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_thr_tsd_unload(phdr_info);
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_thr_sigact_unload(phdr_info);
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}
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__weak_reference(_fork, fork);
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pid_t _fork(void);
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pid_t
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_fork(void)
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{
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struct pthread *curthread;
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struct pthread_atfork *af;
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pid_t ret;
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int errsave;
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int was_threaded;
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int rtld_locks[MAX_RTLD_LOCKS];
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if (!_thr_is_inited())
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return (__sys_fork());
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curthread = _get_curthread();
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THR_UMUTEX_LOCK(curthread, &_thr_atfork_lock);
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/* Run down atfork prepare handlers. */
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TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
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if (af->prepare != NULL)
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af->prepare();
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}
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/*
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* All bets are off as to what should happen soon if the parent
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* process was not so kindly as to set up pthread fork hooks to
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* relinquish all running threads.
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*/
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if (_thr_isthreaded() != 0) {
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was_threaded = 1;
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_malloc_prefork();
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_rtld_atfork_pre(rtld_locks);
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} else {
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was_threaded = 0;
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}
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/*
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* Block all signals until we reach a safe point.
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*/
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_thr_signal_block(curthread);
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_thr_signal_prefork();
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/* Fork a new process: */
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if ((ret = __sys_fork()) == 0) {
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/* Child process */
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errsave = errno;
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curthread->cancel_pending = 0;
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curthread->flags &= ~THR_FLAGS_NEED_SUSPEND;
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/*
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* Thread list will be reinitialized, and later we call
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* _libpthread_init(), it will add us back to list.
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*/
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curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED);
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/* child is a new kernel thread. */
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thr_self(&curthread->tid);
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/* clear other threads locked us. */
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_thr_umutex_init(&curthread->lock);
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_thr_umutex_init(&_thr_atfork_lock);
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_thr_signal_postfork_child();
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if (was_threaded)
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_rtld_atfork_post(rtld_locks);
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_thr_setthreaded(0);
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/* reinitialize libc spinlocks. */
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_thr_spinlock_init();
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_mutex_fork(curthread);
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/* reinitalize library. */
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_libpthread_init(curthread);
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/* Ready to continue, unblock signals. */
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_thr_signal_unblock(curthread);
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if (was_threaded) {
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__isthreaded = 1;
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_malloc_postfork();
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__isthreaded = 0;
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}
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/* Run down atfork child handlers. */
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TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
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if (af->child != NULL)
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af->child();
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}
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} else {
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/* Parent process */
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errsave = errno;
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_thr_signal_postfork();
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/* Ready to continue, unblock signals. */
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_thr_signal_unblock(curthread);
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if (was_threaded) {
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_rtld_atfork_post(rtld_locks);
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_malloc_postfork();
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}
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/* Run down atfork parent handlers. */
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TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
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if (af->parent != NULL)
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af->parent();
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}
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THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
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}
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errno = errsave;
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/* Return the process ID: */
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return (ret);
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}
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