thr_exit.c revision 127523 
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 127523 2004-03-28 14:05:28Z 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
48static void	deadlist_free_threads();
49
50void
51_thread_exit(char *fname, int lineno, char *string)
52{
53	char            s[256];
54
55	/* Prepare an error message string: */
56	snprintf(s, sizeof(s),
57	    "Fatal error '%s' at line %d in file %s (errno = %d)\n",
58	    string, lineno, fname, errno);
59
60	/* Write the string to the standard error file descriptor: */
61	__sys_write(2, s, strlen(s));
62
63	/* Force this process to exit: */
64	/* XXX - Do we want abort to be conditional on _PTHREADS_INVARIANTS? */
65#if defined(_PTHREADS_INVARIANTS)
66	abort();
67#else
68	__sys_exit(1);
69#endif
70}
71
72/*
73 * Only called when a thread is cancelled.  It may be more useful
74 * to call it from pthread_exit() if other ways of asynchronous or
75 * abnormal thread termination can be found.
76 */
77void
78_thread_exit_cleanup(void)
79{
80	/*
81	 * POSIX states that cancellation/termination of a thread should
82	 * not release any visible resources (such as mutexes) and that
83	 * it is the applications responsibility.  Resources that are
84	 * internal to the threads library, including file and fd locks,
85	 * are not visible to the application and need to be released.
86	 */
87	/* Unlock all private mutexes: */
88	_mutex_unlock_private(curthread);
89
90	/*
91	 * This still isn't quite correct because we don't account
92	 * for held spinlocks (see libc/stdlib/malloc.c).
93	 */
94}
95
96void
97_pthread_exit(void *status)
98{
99	pthread_t pthread, joiner;
100	int exitNow = 0;
101
102	/* Check if this thread is already in the process of exiting: */
103	if ((curthread->flags & PTHREAD_EXITING) != 0) {
104		char msg[128];
105		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);
106		PANIC(msg);
107	}
108
109	/* Flag this thread as exiting: */
110	curthread->flags |= PTHREAD_EXITING;
111
112	/* Save the return value: */
113	curthread->ret = status;
114
115	while (curthread->cleanup != NULL) {
116		pthread_cleanup_pop(1);
117	}
118	if (curthread->attr.cleanup_attr != NULL) {
119		curthread->attr.cleanup_attr(curthread->attr.arg_attr);
120	}
121	/* Check if there is thread specific data: */
122	if (curthread->specific != NULL) {
123		/* Run the thread-specific data destructors: */
124		_thread_cleanupspecific();
125	}
126
127	/*
128	 * Remove read-write lock list. It is allocated as-needed.
129	 * Therefore, it must be checked for validity before freeing.
130	 */
131	if (curthread->rwlockList != NULL)
132		free(curthread->rwlockList);
133retry:
134	/*
135	 * Proper lock order, to minimize deadlocks, between joining
136	 * and exiting threads is: DEAD_LIST, THREAD_LIST, exiting, joiner.
137	 * In order to do this *and* protect from races, we must resort
138	 * this test-and-retry loop.
139	 */
140	joiner = curthread->joiner;
141
142	/* Lock the dead list first to maintain correct lock order */
143	DEAD_LIST_LOCK;
144	THREAD_LIST_LOCK;
145	_thread_critical_enter(curthread);
146
147	if (joiner != curthread->joiner) {
148		_thread_critical_exit(curthread);
149		THREAD_LIST_UNLOCK;
150		DEAD_LIST_UNLOCK;
151		goto retry;
152	}
153
154	/* Check if there is a thread joining this one: */
155	if (curthread->joiner != NULL) {
156		pthread = curthread->joiner;
157		UMTX_LOCK(&pthread->lock);
158		curthread->joiner = NULL;
159
160		/* Make the joining thread runnable: */
161		PTHREAD_NEW_STATE(pthread, PS_RUNNING);
162
163		/* Set the return value for the joining thread: */
164		pthread->join_status.ret = curthread->ret;
165		pthread->join_status.error = 0;
166		pthread->join_status.thread = NULL;
167		UMTX_UNLOCK(&pthread->lock);
168
169		/* Make this thread collectable by the garbage collector. */
170		PTHREAD_ASSERT(((curthread->attr.flags & PTHREAD_DETACHED) ==
171		    0), "Cannot join a detached thread");
172		curthread->attr.flags |= PTHREAD_DETACHED;
173	}
174
175	/*
176	 * Free any memory allocated for dead threads.
177	 * Add this thread to the list of dead threads, and
178	 * also remove it from the active threads list.
179	 */
180	deadlist_free_threads();
181	TAILQ_INSERT_HEAD(&_dead_list, curthread, dle);
182	TAILQ_REMOVE(&_thread_list, curthread, tle);
183	PTHREAD_SET_STATE(curthread, PS_DEAD);
184	_thread_critical_exit(curthread);
185
186	/* If we're the last thread, call it quits */
187	if (TAILQ_EMPTY(&_thread_list))
188		exitNow = 1;
189
190	THREAD_LIST_UNLOCK;
191	DEAD_LIST_UNLOCK;
192
193	if (exitNow)
194		exit(0);
195
196	/*
197	 * This function will not return unless we are the last
198	 * thread, which we can't be because we've already checked
199	 * for that.
200	 */
201	_thr_exit();
202
203	/* This point should not be reached. */
204	PANIC("Dead thread has resumed");
205}
206
207/*
208 * Note: this function must be called with the dead thread list
209 *	 locked.
210 */
211static void
212deadlist_free_threads()
213{
214	struct pthread *ptd, *ptdTemp;
215
216	TAILQ_FOREACH_SAFE(ptd, &_dead_list, dle, ptdTemp) {
217		/* Don't destroy the initial thread or non-detached threads. */
218		if (ptd == _thread_initial ||
219		    (ptd->attr.flags & PTHREAD_DETACHED) == 0)
220			continue;
221		TAILQ_REMOVE(&_dead_list, ptd, dle);
222		deadlist_free_onethread(ptd);
223	}
224}
225
226void
227deadlist_free_onethread(struct pthread *ptd)
228{
229
230	if (ptd->attr.stackaddr_attr == NULL && ptd->stack != NULL) {
231		STACK_LOCK;
232		_thread_stack_free(ptd->stack, ptd->attr.stacksize_attr,
233		    ptd->attr.guardsize_attr);
234		STACK_UNLOCK;
235	}
236	_retire_thread(ptd->arch_id);
237	free(ptd);
238}
239