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 "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 int ret = 0; 44 pthread_t thread; 45 46 _thread_enter_cancellation_point(); 47 48 /* Check if the caller has specified an invalid thread: */ 49 if (pthread == NULL || pthread->magic != PTHREAD_MAGIC) { 50 /* Invalid thread: */ 51 _thread_leave_cancellation_point(); 52 return(EINVAL); 53 } 54 55 /* Check if the caller has specified itself: */ 56 if (pthread == curthread) { 57 /* Avoid a deadlock condition: */ 58 _thread_leave_cancellation_point(); 59 return(EDEADLK); 60 } 61 62 /* 63 * Lock the garbage collector mutex to ensure that the garbage 64 * collector is not using the dead thread list. 65 */ 66 if (pthread_mutex_lock(&_gc_mutex) != 0) 67 PANIC("Cannot lock gc mutex"); 68 69 GIANT_LOCK(curthread); 70 71 /* 72 * Search for the specified thread in the list of active threads. This 73 * is done manually here rather than calling _find_thread() because 74 * the searches in _thread_list and _dead_list (as well as setting up 75 * join/detach state) have to be done atomically. 76 */ 77 TAILQ_FOREACH(thread, &_thread_list, tle) 78 if (thread == pthread) 79 break; 80 81 if (thread == NULL) 82 /* 83 * Search for the specified thread in the list of dead threads: 84 */ 85 TAILQ_FOREACH(thread, &_dead_list, dle) 86 if (thread == pthread) 87 break; 88 89 90 /* Check if the thread was not found or has been detached: */ 91 if (thread == NULL || 92 ((pthread->attr.flags & PTHREAD_DETACHED) != 0)) { 93 if (pthread_mutex_unlock(&_gc_mutex) != 0) 94 PANIC("Cannot lock gc mutex"); 95 ret = ESRCH; 96 goto out; 97 98 } 99 if (pthread->joiner != NULL) { 100 /* Multiple joiners are not supported. */ 101 /* XXXTHR - support multiple joiners. */ 102 if (pthread_mutex_unlock(&_gc_mutex) != 0) 103 PANIC("Cannot lock gc mutex"); 104 ret = ENOTSUP; 105 goto out; 106 107 /* Check if the thread is not dead: */ 108 } 109 /* 110 * Unlock the garbage collector mutex, now that the garbage collector 111 * can't be run: 112 */ 113 if (pthread_mutex_unlock(&_gc_mutex) != 0) 114 PANIC("Cannot lock gc mutex"); 115 116 if (pthread->state != PS_DEAD) { 117 /* Set the running thread to be the joiner: */ 118 pthread->joiner = curthread; 119 120 /* Keep track of which thread we're joining to: */ 121 curthread->join_status.thread = pthread; 122 123 while (curthread->join_status.thread == pthread) { 124 PTHREAD_SET_STATE(curthread, PS_JOIN); 125 /* Wait for our signal to wake up. */ 126 GIANT_UNLOCK(curthread); 127 _thread_suspend(curthread, NULL); 128 GIANT_LOCK(curthread); 129 } 130 131 /* 132 * The thread return value and error are set by the thread we're 133 * joining to when it exits or detaches: 134 */ 135 ret = curthread->join_status.error; 136 if ((ret == 0) && (thread_return != NULL)) 137 *thread_return = curthread->join_status.ret; 138 } else { 139 /* 140 * The thread exited (is dead) without being detached, and no 141 * thread has joined it. 142 */ 143 144 /* Check if the return value is required: */ 145 if (thread_return != NULL) { 146 /* Return the thread's return value: */ 147 *thread_return = pthread->ret; 148 } 149 150 /* Make the thread collectable by the garbage collector. */ 151 pthread->attr.flags |= PTHREAD_DETACHED; 152 153 } 154 155 out: 156 GIANT_UNLOCK(curthread); 157 158 _thread_leave_cancellation_point(); 159 160 /* Return the completion status: */ 161 return (ret); 162 } 163