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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by John Birrell. 16 * 4. Neither the name of the author nor the names of any co-contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * $FreeBSD$ 33 */ 34 #include <errno.h> 35 #include <pthread.h> 36 #include <stdlib.h> 37 #include "thr_private.h" 38 39 __weak_reference(_pthread_join, pthread_join); 40 41 int 42 _pthread_join(pthread_t pthread, void **thread_return) 43 { 44 int ret = 0; 45 pthread_t thread; 46 47 /* Check if the caller has specified an invalid thread: */ 48 if (pthread->magic != PTHREAD_MAGIC) 49 /* Invalid thread: */ 50 return(EINVAL); 51 52 /* Check if the caller has specified itself: */ 53 if (pthread == curthread) 54 /* Avoid a deadlock condition: */ 55 return(EDEADLK); 56 57 /* 58 * Search for the specified thread in the list of active threads. This 59 * is done manually here rather than calling _find_thread() because 60 * the searches in _thread_list and _dead_list (as well as setting up 61 * join/detach state) have to be done atomically. 62 */ 63 _thread_sigblock(); 64 DEAD_LIST_LOCK; 65 THREAD_LIST_LOCK; 66 if (!pthread->isdead) { 67 TAILQ_FOREACH(thread, &_thread_list, tle) { 68 if (thread == pthread) { 69 PTHREAD_LOCK(pthread); 70 break; 71 } 72 } 73 } else { 74 TAILQ_FOREACH(thread, &_dead_list, dle) { 75 if (thread == pthread) { 76 PTHREAD_LOCK(pthread); 77 break; 78 } 79 } 80 } 81 82 /* Check if the thread was not found or has been detached: */ 83 if (thread == NULL) { 84 THREAD_LIST_UNLOCK; 85 DEAD_LIST_UNLOCK; 86 _thread_sigunblock(); 87 ret = ESRCH; 88 goto out; 89 } 90 if ((pthread->attr.flags & PTHREAD_DETACHED) != 0) { 91 PTHREAD_UNLOCK(pthread); 92 THREAD_LIST_UNLOCK; 93 DEAD_LIST_UNLOCK; 94 _thread_sigunblock(); 95 ret = EINVAL; 96 goto out; 97 } 98 99 if (pthread->joiner != NULL) { 100 /* Multiple joiners are not supported. */ 101 /* XXXTHR - support multiple joiners. */ 102 PTHREAD_UNLOCK(pthread); 103 THREAD_LIST_UNLOCK; 104 DEAD_LIST_UNLOCK; 105 _thread_sigunblock(); 106 ret = ENOTSUP; 107 goto out; 108 109 } 110 111 /* Check if the thread is not dead: */ 112 if (!pthread->isdead) { 113 /* Set the running thread to be the joiner: */ 114 pthread->joiner = curthread; 115 PTHREAD_UNLOCK(pthread); 116 117 /* Keep track of which thread we're joining to: */ 118 curthread->join_status.thread = pthread; 119 120 while (curthread->join_status.thread == pthread) { 121 /* Wait for our signal to wake up. */ 122 THREAD_LIST_UNLOCK; 123 DEAD_LIST_UNLOCK; 124 _thread_sigunblock(); 125 if (curthread->cancellation != CS_NULL) 126 pthread->joiner = NULL; 127 _thread_enter_cancellation_point(); 128 129 /* 130 * XXX - Workaround to make a join a cancellation 131 * point. Must find a better solution. 132 */ 133 PTHREAD_LOCK(curthread); 134 curthread->flags |= PTHREAD_FLAGS_SUSPENDED; 135 PTHREAD_UNLOCK(curthread); 136 ret = _thread_suspend(curthread, NULL); 137 if (ret != 0 && ret != EAGAIN && ret != EINTR) 138 PANIC("Unable to suspend in join."); 139 PTHREAD_LOCK(curthread); 140 curthread->flags &= ~PTHREAD_FLAGS_SUSPENDED; 141 PTHREAD_UNLOCK(curthread); 142 if (curthread->cancellation != CS_NULL) 143 pthread->joiner = NULL; 144 _thread_leave_cancellation_point(); 145 146 /* 147 * XXX - For correctness reasons. 148 * We must aquire these in the same order and also 149 * importantly, release in the same order because 150 * otherwise we might deadlock with the joined thread 151 * when we attempt to release one of these locks. 152 */ 153 _thread_sigblock(); 154 DEAD_LIST_LOCK; 155 THREAD_LIST_LOCK; 156 } 157 158 /* 159 * The thread return value and error are set by the thread we're 160 * joining to when it exits or detaches: 161 */ 162 ret = curthread->join_status.error; 163 if ((ret == 0) && (thread_return != NULL)) 164 *thread_return = curthread->join_status.ret; 165 THREAD_LIST_UNLOCK; 166 DEAD_LIST_UNLOCK; 167 _thread_sigunblock(); 168 } else { 169 /* 170 * The thread exited (is dead) without being detached, and no 171 * thread has joined it. 172 */ 173 174 /* Check if the return value is required: */ 175 if (thread_return != NULL) { 176 /* Return the thread's return value: */ 177 *thread_return = pthread->ret; 178 } 179 180 /* Free all remaining memory allocated to the thread. */ 181 pthread->attr.flags |= PTHREAD_DETACHED; 182 PTHREAD_UNLOCK(pthread); 183 TAILQ_REMOVE(&_dead_list, pthread, dle); 184 deadlist_free_onethread(pthread); 185 THREAD_LIST_UNLOCK; 186 DEAD_LIST_UNLOCK; 187 _thread_sigunblock(); 188 } 189 190 out: 191 _thread_leave_cancellation_point(); 192 193 /* Return the completion status: */ 194 return (ret); 195 } 196