1 /* 2 * Copyright (c) 1995-1998 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 <unistd.h> 36 #include <fcntl.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <pthread.h> 41 #include "thr_private.h" 42 43 __weak_reference(_pthread_exit, pthread_exit); 44 45 /* thr_exit() */ 46 extern int _thr_exit(void); 47 48 void 49 _thread_exit(char *fname, int lineno, char *string) 50 { 51 char s[256]; 52 53 /* Prepare an error message string: */ 54 snprintf(s, sizeof(s), 55 "Fatal error '%s' at line %d in file %s (errno = %d)\n", 56 string, lineno, fname, errno); 57 58 /* Write the string to the standard error file descriptor: */ 59 __sys_write(2, s, strlen(s)); 60 61 /* Force this process to exit: */ 62 /* XXX - Do we want abort to be conditional on _PTHREADS_INVARIANTS? */ 63 #if defined(_PTHREADS_INVARIANTS) 64 abort(); 65 #else 66 __sys_exit(1); 67 #endif 68 } 69 70 /* 71 * Only called when a thread is cancelled. It may be more useful 72 * to call it from pthread_exit() if other ways of asynchronous or 73 * abnormal thread termination can be found. 74 */ 75 void 76 _thread_exit_cleanup(void) 77 { 78 /* 79 * POSIX states that cancellation/termination of a thread should 80 * not release any visible resources (such as mutexes) and that 81 * it is the applications responsibility. Resources that are 82 * internal to the threads library, including file and fd locks, 83 * are not visible to the application and need to be released. 84 */ 85 /* Unlock all private mutexes: */ 86 _mutex_unlock_private(curthread); 87 88 /* 89 * This still isn't quite correct because we don't account 90 * for held spinlocks (see libc/stdlib/malloc.c). 91 */ 92 } 93 94 void 95 _pthread_exit(void *status) 96 { 97 pthread_t pthread, joiner; 98 int exitNow = 0; 99 100 /* Check if this thread is already in the process of exiting: */ 101 if ((curthread->flags & PTHREAD_EXITING) != 0) { 102 char msg[128]; 103 snprintf(msg, sizeof(msg), "Thread %p has called pthread_exit() from a destructor. POSIX 1003.1 1996 s16.2.5.2 does not allow this!",curthread); 104 PANIC(msg); 105 } 106 107 /* Flag this thread as exiting: */ 108 curthread->flags |= PTHREAD_EXITING; 109 110 /* Save the return value: */ 111 curthread->ret = status; 112 113 while (curthread->cleanup != NULL) { 114 pthread_cleanup_pop(1); 115 } 116 if (curthread->attr.cleanup_attr != NULL) { 117 curthread->attr.cleanup_attr(curthread->attr.arg_attr); 118 } 119 /* Check if there is thread specific data: */ 120 if (curthread->specific != NULL) { 121 /* Run the thread-specific data destructors: */ 122 _thread_cleanupspecific(); 123 } 124 125 retry: 126 /* 127 * Proper lock order, to minimize deadlocks, between joining 128 * and exiting threads is: DEAD_LIST, THREAD_LIST, exiting, joiner. 129 * In order to do this *and* protect from races, we must resort 130 * this test-and-retry loop. 131 */ 132 joiner = curthread->joiner; 133 134 /* Lock the dead list first to maintain correct lock order */ 135 DEAD_LIST_LOCK; 136 THREAD_LIST_LOCK; 137 _thread_critical_enter(curthread); 138 139 if (joiner != curthread->joiner) { 140 _thread_critical_exit(curthread); 141 THREAD_LIST_UNLOCK; 142 DEAD_LIST_UNLOCK; 143 goto retry; 144 } 145 146 /* Check if there is a thread joining this one: */ 147 if (curthread->joiner != NULL) { 148 pthread = curthread->joiner; 149 UMTX_LOCK(&pthread->lock); 150 curthread->joiner = NULL; 151 152 /* Make the joining thread runnable: */ 153 PTHREAD_NEW_STATE(pthread, PS_RUNNING); 154 155 /* Set the return value for the joining thread: */ 156 pthread->join_status.ret = curthread->ret; 157 pthread->join_status.error = 0; 158 pthread->join_status.thread = NULL; 159 UMTX_UNLOCK(&pthread->lock); 160 161 /* Make this thread collectable by the garbage collector. */ 162 PTHREAD_ASSERT(((curthread->attr.flags & PTHREAD_DETACHED) == 163 0), "Cannot join a detached thread"); 164 curthread->attr.flags |= PTHREAD_DETACHED; 165 } 166 167 /* 168 * Add this thread to the list of dead threads, and 169 * also remove it from the active threads list. 170 */ 171 TAILQ_INSERT_HEAD(&_dead_list, curthread, dle); 172 TAILQ_REMOVE(&_thread_list, curthread, tle); 173 PTHREAD_SET_STATE(curthread, PS_DEAD); 174 _thread_critical_exit(curthread); 175 176 /* If we're the last thread, call it quits */ 177 if (TAILQ_EMPTY(&_thread_list)) 178 exitNow = 1; 179 180 THREAD_LIST_UNLOCK; 181 182 /* 183 * Signal the garbage collector thread that there is something 184 * to clean up. But don't allow it to free the memory until after 185 * it is retired by holding on to the dead list lock. 186 */ 187 if (pthread_cond_signal(&_gc_cond) != 0) 188 PANIC("Cannot signal gc cond"); 189 190 if (exitNow) 191 exit(0); 192 193 DEAD_LIST_UNLOCK; 194 195 /* 196 * This function will not return unless we are the last 197 * thread, which we can't be because we've already checked 198 * for that. 199 */ 200 _thr_exit(); 201 202 /* This point should not be reached. */ 203 PANIC("Dead thread has resumed"); 204 } 205