lib/libkse/thread/thr_join.c

   1 /*
   2  * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD$
  30  */
  31
  32 #include "namespace.h"
  33 #include <errno.h>
  34 #include <pthread.h>
  35 #include "un-namespace.h"
  36 #include "thr_private.h"
  37
  38 __weak_reference(_pthread_join, pthread_join);
  39
  40 int
  41 _pthread_join(pthread_t pthread, void **thread_return)
  42 {
  43         struct pthread *curthread = _get_curthread();
  44         void *tmp;
  45         kse_critical_t crit;
  46         int ret = 0;
  47
  48         _thr_cancel_enter(curthread);
  49
  50         /* Check if the caller has specified an invalid thread: */
  51         if (pthread == NULL || pthread->magic != THR_MAGIC) {
  52                 /* Invalid thread: */
  53                 _thr_cancel_leave(curthread, 1);
  54                 return (EINVAL);
  55         }
  56
  57         /* Check if the caller has specified itself: */
  58         if (pthread == curthread) {
  59                 /* Avoid a deadlock condition: */
  60                 _thr_cancel_leave(curthread, 1);
  61                 return (EDEADLK);
  62         }
  63
  64         /*
  65          * Find the thread in the list of active threads or in the
  66          * list of dead threads:
  67          */
  68         if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/1)) != 0) {
  69                 /* Return an error: */
  70                 _thr_cancel_leave(curthread, 1);
  71                 return (ESRCH);
  72         }
  73
  74         THR_SCHED_LOCK(curthread, pthread);
  75         /* Check if this thread has been detached: */
  76         if ((pthread->attr.flags & PTHREAD_DETACHED) != 0) {
  77                 THR_SCHED_UNLOCK(curthread, pthread);
  78                 /* Remove the reference and return an error: */
  79                 _thr_ref_delete(curthread, pthread);
  80                 ret = EINVAL;
  81         } else {
  82                 /* Lock the target thread while checking its state. */
  83                 if (pthread->state == PS_DEAD) {
  84                         /* Return the thread's return value: */
  85                         tmp = pthread->ret;
  86
  87                         /* Detach the thread. */
  88                         pthread->attr.flags |= PTHREAD_DETACHED;
  89
  90                         /* Unlock the thread. */
  91                         THR_SCHED_UNLOCK(curthread, pthread);
  92
  93                         /*
  94                          * Remove the thread from the list of active
  95                          * threads and add it to the GC list.
  96                          */
  97                         crit = _kse_critical_enter();
  98                         KSE_LOCK_ACQUIRE(curthread->kse, &_thread_list_lock);
  99                         THR_LIST_REMOVE(pthread);
 100                         THR_GCLIST_ADD(pthread);
 101                         KSE_LOCK_RELEASE(curthread->kse, &_thread_list_lock);
 102                         _kse_critical_leave(crit);
 103
 104                         /* Remove the reference. */
 105                         _thr_ref_delete(curthread, pthread);
 106                         if (thread_return != NULL)
 107                                 *thread_return = tmp;
 108                 }
 109                 else if (pthread->joiner != NULL) {
 110                         /* Unlock the thread and remove the reference. */
 111                         THR_SCHED_UNLOCK(curthread, pthread);
 112                         _thr_ref_delete(curthread, pthread);
 113
 114                         /* Multiple joiners are not supported. */
 115                         ret = ENOTSUP;
 116                 }
 117                 else {
 118                         /* Set the running thread to be the joiner: */
 119                         pthread->joiner = curthread;
 120
 121                         /* Keep track of which thread we're joining to: */
 122                         curthread->join_status.thread = pthread;
 123
 124                         /* Unlock the thread and remove the reference. */
 125                         THR_SCHED_UNLOCK(curthread, pthread);
 126                         _thr_ref_delete(curthread, pthread);
 127
 128                         THR_SCHED_LOCK(curthread, curthread);
 129                         while (curthread->join_status.thread == pthread) {
 130                                 THR_SET_STATE(curthread, PS_JOIN);
 131                                 THR_SCHED_UNLOCK(curthread, curthread);
 132                                 /* Schedule the next thread: */
 133                                 _thr_sched_switch(curthread);
 134                                 THR_SCHED_LOCK(curthread, curthread);
 135                         }
 136                         THR_SCHED_UNLOCK(curthread, curthread);
 137
 138                         if ((curthread->cancelflags & THR_CANCELLING) &&
 139                            !(curthread->cancelflags & PTHREAD_CANCEL_DISABLE)) {
 140                                 if (_thr_ref_add(curthread, pthread, 1) == 0) {
 141                                         THR_SCHED_LOCK(curthread, pthread);
 142                                         pthread->joiner = NULL;
 143                                         THR_SCHED_UNLOCK(curthread, pthread);
 144                                         _thr_ref_delete(curthread, pthread);
 145                                 }
 146                                 _pthread_exit(PTHREAD_CANCELED);
 147                         }
 148
 149                         /*
 150                          * The thread return value and error are set by the
 151                          * thread we're joining to when it exits or detaches:
 152                          */
 153                         ret = curthread->join_status.error;
 154                         if ((ret == 0) && (thread_return != NULL))
 155                                 *thread_return = curthread->join_status.ret;
 156                 }
 157         }
 158         _thr_cancel_leave(curthread, 1);
 159
 160         /* Return the completion status: */
 161         return (ret);
 162 }