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/* ==== pthread_join.c =======================================================
* Copyright (c) 1994 by Chris Provenzano, proven@mit.edu
* 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 Chris Provenzano.
* 4. The name of Chris Provenzano may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO 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.
*
* Description : pthread_join function.
*
* 1.00 94/01/15 proven
* -Started coding this file.
*/
#ifndef lint
static const char rcsid[] = "$Id$";
#endif
#include <pthread.h>
#include <errno.h>
static int testDeadlock( struct pthread_queue *queue, pthread_t target );
/* ==========================================================================
* pthread_join()
*/
int pthread_join(pthread_t pthread, void **thread_return)
{
int ret;
pthread_sched_prevent();
/* Ensure they gave us a legal pthread pointer */
if( ! __pthread_is_valid( pthread ) ) {
pthread_sched_resume();
return(EINVAL);
}
/* Check that thread isn't detached already */
if (pthread->attr.flags & PTHREAD_DETACHED) {
pthread_sched_resume();
return(ESRCH);
}
/*
* Now check if other thread has exited
* Note: This must happen after checking detached state.
*/
if (pthread_queue_remove(&pthread_dead_queue, pthread) != OK) {
/* Before we pend on the join, ensure there is no dead lock */
if( testDeadlock( &pthread_run->join_queue, pthread ) == NOTOK ) {
ret = EDEADLK;
} else {
pthread_queue_enq(&(pthread->join_queue), pthread_run);
SET_PF_AT_CANCEL_POINT(pthread_run); /* This is a cancel point */
pthread_resched_resume(PS_JOIN);
CLEAR_PF_AT_CANCEL_POINT(pthread_run); /* No longer at cancel point */
pthread_sched_prevent();
if (pthread_queue_remove(&pthread_dead_queue, pthread) == OK) {
pthread_queue_enq(&pthread_alloc_queue, pthread);
pthread->attr.flags |= PTHREAD_DETACHED;
pthread->state = PS_UNALLOCED;
if (thread_return) {
*thread_return = pthread->ret;
}
ret = OK;
} else {
ret = ESRCH;
}
}
} else {
/* Just get the return value and detach the thread */
pthread_queue_enq(&pthread_alloc_queue, pthread);
pthread->attr.flags |= PTHREAD_DETACHED;
pthread->state = PS_UNALLOCED;
if (thread_return) {
*thread_return = pthread->ret;
}
ret = OK;
}
pthread_sched_resume();
return(ret);
}
/*----------------------------------------------------------------------
* Function: testDeadlock
* Purpose: recursive queue walk to check for deadlocks
* Args:
* queue = the queue to walk
* pthread = target to scan for
* Returns:
* OK = no deadlock, NOTOK = deadlock
* Notes:
*----------------------------------------------------------------------*/
static int
testDeadlock( struct pthread_queue *queue, pthread_t target )
{
pthread_t t;
if( queue == NULL )
return OK; /* Empty queue, obviously ok */
for( t = queue->q_next; t; t = t->next ) {
if( t == target )
return NOTOK; /* bang, your dead */
if( testDeadlock( &t->join_queue, target ) == NOTOK ) {
return NOTOK;
}
}
return OK; /* No deadlock */
}
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