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, dead; 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 ret = 0; 64 dead = 0; 65 thread = NULL; 66 _thread_sigblock(); 67 DEAD_LIST_LOCK; 68 THREAD_LIST_LOCK; 69 if (!pthread->isdead) { 70 TAILQ_FOREACH(thread, &_thread_list, tle) { 71 if (thread == pthread) { 72 PTHREAD_LOCK(pthread); 73 break; 74 } 75 } 76 } 77 if (thread == NULL) { 78 TAILQ_FOREACH(thread, &_dead_list, dle) { 79 if (thread == pthread) { 80 PTHREAD_LOCK(pthread); 81 dead = 1; 82 break; 83 } 84 } 85 } 86 87 /* Check if the thread was not found or has been detached: */ 88 if (thread == NULL) { 89 THREAD_LIST_UNLOCK; 90 DEAD_LIST_UNLOCK; 91 _thread_sigunblock(); 92 ret = ESRCH; 93 goto out; 94 } 95 if ((pthread->attr.flags & PTHREAD_DETACHED) != 0) { 96 PTHREAD_UNLOCK(pthread); 97 THREAD_LIST_UNLOCK; 98 DEAD_LIST_UNLOCK; 99 _thread_sigunblock(); 100 ret = EINVAL; 101 goto out; 102 } 103 104 if (pthread->joiner != NULL) { 105 /* Multiple joiners are not supported. */ 106 /* XXXTHR - support multiple joiners. */ 107 PTHREAD_UNLOCK(pthread); 108 THREAD_LIST_UNLOCK; 109 DEAD_LIST_UNLOCK; 110 _thread_sigunblock(); 111 ret = ENOTSUP; 112 goto out; 113 114 } 115 116 /* Check if the thread is not dead: */ 117 if (!dead) { 118 /* Set the running thread to be the joiner: */ 119 pthread->joiner = curthread; 120 PTHREAD_UNLOCK(pthread); 121 122 /* Keep track of which thread we're joining to: */ 123 curthread->join_status.thread = pthread; 124 125 while (curthread->join_status.thread == pthread) { 126 /* Wait for our signal to wake up. */ 127 THREAD_LIST_UNLOCK; 128 DEAD_LIST_UNLOCK; 129 _thread_sigunblock(); 130 if (curthread->cancellation != CS_NULL) 131 pthread->joiner = NULL; 132 _thread_enter_cancellation_point(); 133 134 /* 135 * XXX - Workaround to make a join a cancellation 136 * point. Must find a better solution. 137 */ 138 PTHREAD_LOCK(curthread); 139 curthread->flags |= PTHREAD_FLAGS_SUSPENDED; 140 PTHREAD_UNLOCK(curthread); 141 ret = _thread_suspend(curthread, NULL); 142 if (ret != 0 && ret != EAGAIN && ret != EINTR) 143 PANIC("Unable to suspend in join."); 144 PTHREAD_LOCK(curthread); 145 curthread->flags &= ~PTHREAD_FLAGS_SUSPENDED; 146 PTHREAD_UNLOCK(curthread); 147 if (curthread->cancellation != CS_NULL) 148 pthread->joiner = NULL; 149 _thread_leave_cancellation_point(); 150 151 /* 152 * XXX - For correctness reasons. 153 * We must aquire these in the same order and also 154 * importantly, release in the same order because 155 * otherwise we might deadlock with the joined thread 156 * when we attempt to release one of these locks. 157 */ 158 _thread_sigblock(); 159 DEAD_LIST_LOCK; 160 THREAD_LIST_LOCK; 161 } 162 163 /* 164 * The thread return value and error are set by the thread we're 165 * joining to when it exits or detaches: 166 */ 167 ret = curthread->join_status.error; 168 if ((ret == 0) && (thread_return != NULL)) 169 *thread_return = curthread->join_status.ret; 170 THREAD_LIST_UNLOCK; 171 DEAD_LIST_UNLOCK; 172 _thread_sigunblock(); 173 } else { 174 /* 175 * The thread exited (is dead) without being detached, and no 176 * thread has joined it. 177 */ 178 179 /* Check if the return value is required: */ 180 if (thread_return != NULL) { 181 /* Return the thread's return value: */ 182 *thread_return = pthread->ret; 183 } 184 185 /* Free all remaining memory allocated to the thread. */ 186 pthread->attr.flags |= PTHREAD_DETACHED; 187 PTHREAD_UNLOCK(pthread); 188 TAILQ_REMOVE(&_dead_list, pthread, dle); 189 deadlist_free_onethread(pthread); 190 THREAD_LIST_UNLOCK; 191 DEAD_LIST_UNLOCK; 192 _thread_sigunblock(); 193 } 194 195 out: 196 _thread_leave_cancellation_point(); 197 198 /* Return the completion status: */ 199 return (ret); 200 } 201