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