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Diffstat (limited to 'mit-pthreads/pthreads/pthread_join.c')
| -rw-r--r-- | mit-pthreads/pthreads/pthread_join.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/mit-pthreads/pthreads/pthread_join.c b/mit-pthreads/pthreads/pthread_join.c new file mode 100644 index 00000000000..879250020a1 --- /dev/null +++ b/mit-pthreads/pthreads/pthread_join.c @@ -0,0 +1,139 @@ +/* ==== 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 */ +} |