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 _thread_enter_cancellation_point(); 48 49 /* Check if the caller has specified an invalid thread: */ 50 if (pthread == NULL || pthread->magic != PTHREAD_MAGIC) { 51 /* Invalid thread: */ 52 _thread_leave_cancellation_point(); 53 return(EINVAL); 54 } 55 56 /* Check if the caller has specified itself: */ 57 if (pthread == curthread) { 58 /* Avoid a deadlock condition: */ 59 _thread_leave_cancellation_point(); 60 return(EDEADLK); 61 } 62 63 /* 64 * Search for the specified thread in the list of active threads. This 65 * is done manually here rather than calling _find_thread() because 66 * the searches in _thread_list and _dead_list (as well as setting up 67 * join/detach state) have to be done atomically. 68 */ 69 DEAD_LIST_LOCK; 70 THREAD_LIST_LOCK; 71 TAILQ_FOREACH(thread, &_thread_list, tle) 72 if (thread == pthread) { 73 UMTX_LOCK(&pthread->lock); 74 break; 75 } 76 77 if (thread == NULL) 78 /* 79 * Search for the specified thread in the list of dead threads: 80 */ 81 TAILQ_FOREACH(thread, &_dead_list, dle) 82 if (thread == pthread) { 83 UMTX_LOCK(&pthread->lock); 84 break; 85 } 86 87 /* Check if the thread was not found or has been detached: */ 88 if (thread == NULL || 89 ((pthread->attr.flags & PTHREAD_DETACHED) != 0)) { 90 if (thread != NULL) 91 UMTX_UNLOCK(&pthread->lock); 92 THREAD_LIST_UNLOCK; 93 DEAD_LIST_UNLOCK; 94 ret = ESRCH; 95 goto out; 96 97 } 98 if (pthread->joiner != NULL) { 99 /* Multiple joiners are not supported. */ 100 /* XXXTHR - support multiple joiners. */ 101 UMTX_UNLOCK(&pthread->lock); 102 THREAD_LIST_UNLOCK; 103 DEAD_LIST_UNLOCK; 104 ret = ENOTSUP; 105 goto out; 106 107 } 108 109 /* Check if the thread is not dead: */ 110 if (pthread->state != PS_DEAD) { 111 /* Set the running thread to be the joiner: */ 112 pthread->joiner = curthread; 113 UMTX_UNLOCK(&pthread->lock); 114 _thread_critical_enter(curthread); 115 116 /* Keep track of which thread we're joining to: */ 117 curthread->join_status.thread = pthread; 118 119 while (curthread->join_status.thread == pthread) { 120 PTHREAD_SET_STATE(curthread, PS_JOIN); 121 /* Wait for our signal to wake up. */ 122 _thread_critical_exit(curthread); 123 THREAD_LIST_UNLOCK; 124 DEAD_LIST_UNLOCK; 125 ret = _thread_suspend(curthread, NULL); 126 if (ret != 0 && ret != EAGAIN && ret != EINTR) 127 PANIC("Unable to suspend in join."); 128 129 /* 130 * XXX - For correctness reasons. 131 * We must aquire these in the same order and also 132 * importantly, release in the same order, order because 133 * otherwise we might deadlock with the joined thread 134 * when we attempt to release one of these locks. 135 */ 136 DEAD_LIST_LOCK; 137 THREAD_LIST_LOCK; 138 _thread_critical_enter(curthread); 139 } 140 141 /* 142 * The thread return value and error are set by the thread we're 143 * joining to when it exits or detaches: 144 */ 145 ret = curthread->join_status.error; 146 if ((ret == 0) && (thread_return != NULL)) 147 *thread_return = curthread->join_status.ret; 148 _thread_critical_exit(curthread); 149 THREAD_LIST_UNLOCK; 150 DEAD_LIST_UNLOCK; 151 } else { 152 /* 153 * The thread exited (is dead) without being detached, and no 154 * thread has joined it. 155 */ 156 157 /* Check if the return value is required: */ 158 if (thread_return != NULL) { 159 /* Return the thread's return value: */ 160 *thread_return = pthread->ret; 161 } 162 163 /* Make the thread collectable by the garbage collector. */ 164 pthread->attr.flags |= PTHREAD_DETACHED; 165 UMTX_UNLOCK(&pthread->lock); 166 THREAD_LIST_UNLOCK; 167 if (pthread_cond_signal(&_gc_cond) != 0) 168 PANIC("Cannot signal gc cond"); 169 DEAD_LIST_UNLOCK; 170 } 171 172 out: 173 _thread_leave_cancellation_point(); 174 175 /* Return the completion status: */ 176 return (ret); 177 } 178