thr_exit.c revision 117277 
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: head/lib/libthr/thread/thr_exit.c 117277 2003-07-06 10:18:48Z mtm $
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() */
46extern int _thr_exit(void);
47
48void
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 */
75void
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
94void
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
125retry:
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