/* ==== 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 */ }