843d4004b3
signals instead of having more intricate knowledge of thread state within signal handling. Simplify signal code because of above (by David Xu). Use macros for libpthread usage of pthread_cleanup_push() and pthread_cleanup_pop(). This removes some instances of malloc() and free() from the semaphore and pthread_once() implementations. When single threaded and forking(), make sure that the current thread's signal mask is inherited by the forked thread. Use private mutexes for libc and libpthread. Signals are deferred while threads hold private mutexes. This fix also breaks www/linuxpluginwrapper; a patch that fixes it is at http://people.freebsd.org/~deischen/kse/linuxpluginwrapper.diff Fix race condition in condition variables where handling a signal (pthread_kill() or kill()) may not see a wakeup (pthread_cond_signal() or pthread_cond_broadcast()). In collaboration with: davidxu
99 lines
3.5 KiB
C
99 lines
3.5 KiB
C
/*
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* Copyright (c) 1995 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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. 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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* $FreeBSD$
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*/
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#include "namespace.h"
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#include <pthread.h>
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#include "un-namespace.h"
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#include "thr_private.h"
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__weak_reference(_pthread_once, pthread_once);
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#define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT
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#define ONCE_DONE PTHREAD_DONE_INIT
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#define ONCE_IN_PROGRESS 0x02
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#define ONCE_MASK 0x03
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static pthread_mutex_t once_lock = PTHREAD_MUTEX_INITIALIZER;
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static pthread_cond_t once_cv = PTHREAD_COND_INITIALIZER;
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/*
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* POSIX:
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* The pthread_once() function is not a cancellation point. However,
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* if init_routine is a cancellation point and is canceled, the effect
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* on once_control shall be as if pthread_once() was never called.
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*/
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static void
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once_cancel_handler(void *arg)
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{
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pthread_once_t *once_control = arg;
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_pthread_mutex_lock(&once_lock);
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once_control->state = ONCE_NEVER_DONE;
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_pthread_mutex_unlock(&once_lock);
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_pthread_cond_broadcast(&once_cv);
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}
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int
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_pthread_once(pthread_once_t *once_control, void (*init_routine) (void))
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{
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struct pthread *curthread;
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int wakeup = 0;
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if (once_control->state == ONCE_DONE)
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return (0);
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_pthread_mutex_lock(&once_lock);
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while (*(volatile int *)&(once_control->state) == ONCE_IN_PROGRESS)
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_pthread_cond_wait(&once_cv, &once_lock);
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/*
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* If previous thread was canceled, then the state still
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* could be ONCE_NEVER_DONE, we need to check it again.
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*/
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if (*(volatile int *)&(once_control->state) == ONCE_NEVER_DONE) {
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once_control->state = ONCE_IN_PROGRESS;
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_pthread_mutex_unlock(&once_lock);
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curthread = _get_curthread();
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THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control);
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init_routine();
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THR_CLEANUP_POP(curthread, 0);
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_pthread_mutex_lock(&once_lock);
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once_control->state = ONCE_DONE;
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wakeup = 1;
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}
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_pthread_mutex_unlock(&once_lock);
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if (wakeup)
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_pthread_cond_broadcast(&once_cv);
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return (0);
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}
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