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/*
* Copyright (c) 1995 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.
*
* $FreeBSD$
*/
#include <errno.h>
#include <pthread.h>
#include <stdlib.h>
#include "thr_private.h"
__weak_reference(_pthread_join, pthread_join);
int
_pthread_join(pthread_t pthread, void **thread_return)
{
int ret = 0;
pthread_t thread;
_thread_enter_cancellation_point();
/* Check if the caller has specified an invalid thread: */
if (pthread == NULL || pthread->magic != PTHREAD_MAGIC) {
/* Invalid thread: */
_thread_leave_cancellation_point();
return(EINVAL);
}
/* Check if the caller has specified itself: */
if (pthread == curthread) {
/* Avoid a deadlock condition: */
_thread_leave_cancellation_point();
return(EDEADLK);
}
/*
* Search for the specified thread in the list of active threads. This
* is done manually here rather than calling _find_thread() because
* the searches in _thread_list and _dead_list (as well as setting up
* join/detach state) have to be done atomically.
*/
DEAD_LIST_LOCK;
THREAD_LIST_LOCK;
TAILQ_FOREACH(thread, &_thread_list, tle)
if (thread == pthread) {
UMTX_LOCK(&pthread->lock);
break;
}
if (thread == NULL)
/*
* Search for the specified thread in the list of dead threads:
*/
TAILQ_FOREACH(thread, &_dead_list, dle)
if (thread == pthread) {
UMTX_LOCK(&pthread->lock);
break;
}
/* Check if the thread was not found or has been detached: */
if (thread == NULL ||
((pthread->attr.flags & PTHREAD_DETACHED) != 0)) {
if (thread != NULL)
UMTX_UNLOCK(&pthread->lock);
THREAD_LIST_UNLOCK;
DEAD_LIST_UNLOCK;
ret = ESRCH;
goto out;
}
if (pthread->joiner != NULL) {
/* Multiple joiners are not supported. */
/* XXXTHR - support multiple joiners. */
UMTX_UNLOCK(&pthread->lock);
THREAD_LIST_UNLOCK;
DEAD_LIST_UNLOCK;
ret = ENOTSUP;
goto out;
}
/* Check if the thread is not dead: */
if (pthread->state != PS_DEAD) {
/* Set the running thread to be the joiner: */
pthread->joiner = curthread;
UMTX_UNLOCK(&pthread->lock);
_thread_critical_enter(curthread);
/* Keep track of which thread we're joining to: */
curthread->join_status.thread = pthread;
while (curthread->join_status.thread == pthread) {
PTHREAD_SET_STATE(curthread, PS_JOIN);
/* Wait for our signal to wake up. */
_thread_critical_exit(curthread);
THREAD_LIST_UNLOCK;
DEAD_LIST_UNLOCK;
ret = _thread_suspend(curthread, NULL);
if (ret != 0 && ret != EAGAIN && ret != EINTR)
PANIC("Unable to suspend in join.");
/*
* XXX - For correctness reasons.
* We must aquire these in the same order and also
* importantly, release in the same order, order because
* otherwise we might deadlock with the joined thread
* when we attempt to release one of these locks.
*/
DEAD_LIST_LOCK;
THREAD_LIST_LOCK;
_thread_critical_enter(curthread);
}
/*
* The thread return value and error are set by the thread we're
* joining to when it exits or detaches:
*/
ret = curthread->join_status.error;
if ((ret == 0) && (thread_return != NULL))
*thread_return = curthread->join_status.ret;
_thread_critical_exit(curthread);
THREAD_LIST_UNLOCK;
DEAD_LIST_UNLOCK;
} else {
/*
* The thread exited (is dead) without being detached, and no
* thread has joined it.
*/
/* Check if the return value is required: */
if (thread_return != NULL) {
/* Return the thread's return value: */
*thread_return = pthread->ret;
}
/* Make the thread collectable by the garbage collector. */
pthread->attr.flags |= PTHREAD_DETACHED;
UMTX_UNLOCK(&pthread->lock);
THREAD_LIST_UNLOCK;
if (pthread_cond_signal(&_gc_cond) != 0)
PANIC("Cannot signal gc cond");
DEAD_LIST_UNLOCK;
}
out:
_thread_leave_cancellation_point();
/* Return the completion status: */
return (ret);
}
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