thr_exit.c revision 213182 
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. Neither the name of the author nor the names of any co-contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: head/lib/libthr/thread/thr_exit.c 213182 2010-09-26 06:45:24Z davidxu $
30 */
31
32#include "namespace.h"
33#include <errno.h>
34#ifdef _PTHREAD_FORCED_UNWIND
35#include <dlfcn.h>
36#endif
37#include <stdio.h>
38#include <stdlib.h>
39#include <pthread.h>
40#include <sys/types.h>
41#include <sys/signalvar.h>
42#include "un-namespace.h"
43
44#include "libc_private.h"
45#include "thr_private.h"
46
47void	_pthread_exit(void *status);
48
49static void	exit_thread(void) __dead2;
50
51__weak_reference(_pthread_exit, pthread_exit);
52
53#ifdef _PTHREAD_FORCED_UNWIND
54static int message_printed;
55
56static void thread_unwind(void) __dead2;
57#ifdef PIC
58static void thread_uw_init(void);
59static _Unwind_Reason_Code thread_unwind_stop(int version,
60	_Unwind_Action actions,
61	_Unwind_Exception_Class exc_class,
62	struct _Unwind_Exception *exc_obj,
63	struct _Unwind_Context *context, void *stop_parameter);
64/* unwind library pointers */
65static _Unwind_Reason_Code (*uwl_forcedunwind)(struct _Unwind_Exception *,
66	_Unwind_Stop_Fn, void *);
67static _Unwind_Word (*uwl_getcfa)(struct _Unwind_Context *);
68
69static void
70thread_uw_init(void)
71{
72	static int inited = 0;
73	Dl_info dlinfo;
74	void *handle;
75	void *forcedunwind, *getcfa;
76
77	if (inited)
78	    return;
79	handle = RTLD_DEFAULT;
80	if ((forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind")) != NULL) {
81	    if (dladdr(forcedunwind, &dlinfo)) {
82		/*
83		 * Make sure the address is always valid by holding the library,
84		 * also assume functions are in same library.
85		 */
86		if ((handle = dlopen(dlinfo.dli_fname, RTLD_LAZY)) != NULL) {
87		    forcedunwind = dlsym(handle, "_Unwind_ForcedUnwind");
88		    getcfa = dlsym(handle, "_Unwind_GetCFA");
89		    if (forcedunwind != NULL && getcfa != NULL) {
90			uwl_getcfa = getcfa;
91			atomic_store_rel_ptr((volatile void *)&uwl_forcedunwind,
92				(uintptr_t)forcedunwind);
93		    } else {
94			dlclose(handle);
95		    }
96		}
97	    }
98	}
99	inited = 1;
100}
101
102_Unwind_Reason_Code
103_Unwind_ForcedUnwind(struct _Unwind_Exception *ex, _Unwind_Stop_Fn stop_func,
104	void *stop_arg)
105{
106	return (*uwl_forcedunwind)(ex, stop_func, stop_arg);
107}
108
109_Unwind_Word
110_Unwind_GetCFA(struct _Unwind_Context *context)
111{
112	return (*uwl_getcfa)(context);
113}
114#else
115#pragma weak _Unwind_GetCFA
116#pragma weak _Unwind_ForcedUnwind
117#endif /* PIC */
118
119static void
120thread_unwind_cleanup(_Unwind_Reason_Code code, struct _Unwind_Exception *e)
121{
122	/*
123	 * Specification said that _Unwind_Resume should not be used here,
124	 * instead, user should rethrow the exception. For C++ user, they
125	 * should put "throw" sentence in catch(...) block.
126	 */
127	PANIC("exception should be rethrown");
128}
129
130static _Unwind_Reason_Code
131thread_unwind_stop(int version, _Unwind_Action actions,
132	_Unwind_Exception_Class exc_class,
133	struct _Unwind_Exception *exc_obj,
134	struct _Unwind_Context *context, void *stop_parameter)
135{
136	struct pthread *curthread = _get_curthread();
137	struct pthread_cleanup *cur;
138	uintptr_t cfa;
139	int done = 0;
140
141	/* XXX assume stack grows down to lower address */
142
143	cfa = _Unwind_GetCFA(context);
144	if (actions & _UA_END_OF_STACK ||
145	    cfa >= (uintptr_t)curthread->unwind_stackend) {
146		done = 1;
147	}
148
149	while ((cur = curthread->cleanup) != NULL &&
150	       (done || (uintptr_t)cur <= cfa)) {
151		__pthread_cleanup_pop_imp(1);
152	}
153
154	if (done)
155		exit_thread(); /* Never return! */
156
157	return (_URC_NO_REASON);
158}
159
160static void
161thread_unwind(void)
162{
163	struct pthread  *curthread = _get_curthread();
164
165	curthread->ex.exception_class = 0;
166	curthread->ex.exception_cleanup = thread_unwind_cleanup;
167	_Unwind_ForcedUnwind(&curthread->ex, thread_unwind_stop, NULL);
168	PANIC("_Unwind_ForcedUnwind returned");
169}
170
171#endif
172
173void
174_thread_exit(const char *fname, int lineno, const char *msg)
175{
176
177	/* Write an error message to the standard error file descriptor: */
178	_thread_printf(2,
179	    "Fatal error '%s' at line %d in file %s (errno = %d)\n",
180	    msg, lineno, fname, errno);
181
182	abort();
183}
184
185void
186_pthread_exit(void *status)
187{
188	_pthread_exit_mask(status, NULL);
189}
190
191void
192_pthread_exit_mask(void *status, sigset_t *mask)
193{
194	struct pthread *curthread = _get_curthread();
195
196	/* Check if this thread is already in the process of exiting: */
197	if (curthread->cancelling) {
198		char msg[128];
199		snprintf(msg, sizeof(msg), "Thread %p has called "
200		    "pthread_exit() from a destructor. POSIX 1003.1 "
201		    "1996 s16.2.5.2 does not allow this!", curthread);
202		PANIC(msg);
203	}
204
205	/* Flag this thread as exiting. */
206	curthread->cancelling = 1;
207	curthread->no_cancel = 1;
208	curthread->cancel_async = 0;
209	curthread->cancel_point = 0;
210	if (mask != NULL)
211		__sys_sigprocmask(SIG_SETMASK, mask, NULL);
212	if (curthread->unblock_sigcancel) {
213		sigset_t set;
214
215		curthread->unblock_sigcancel = 0;
216		SIGEMPTYSET(set);
217		SIGADDSET(set, SIGCANCEL);
218		__sys_sigprocmask(SIG_UNBLOCK, mask, NULL);
219	}
220
221	/* Save the return value: */
222	curthread->ret = status;
223#ifdef _PTHREAD_FORCED_UNWIND
224
225#ifdef PIC
226	thread_uw_init();
227#endif /* PIC */
228
229#ifdef PIC
230	if (uwl_forcedunwind != NULL) {
231#else
232	if (_Unwind_ForcedUnwind != NULL) {
233#endif
234		if (curthread->unwind_disabled) {
235			if (message_printed == 0) {
236				message_printed = 1;
237				_thread_printf(2, "Warning: old _pthread_cleanup_push was called, "
238				  	"stack unwinding is disabled.\n");
239			}
240			goto cleanup;
241		}
242		thread_unwind();
243
244	} else {
245cleanup:
246		while (curthread->cleanup != NULL) {
247			__pthread_cleanup_pop_imp(1);
248		}
249		exit_thread();
250	}
251
252#else
253	while (curthread->cleanup != NULL) {
254		__pthread_cleanup_pop_imp(1);
255	}
256
257	exit_thread();
258#endif /* _PTHREAD_FORCED_UNWIND */
259}
260
261static void
262exit_thread(void)
263{
264	struct pthread *curthread = _get_curthread();
265
266	/* Check if there is thread specific data: */
267	if (curthread->specific != NULL) {
268		/* Run the thread-specific data destructors: */
269		_thread_cleanupspecific();
270	}
271
272	if (!_thr_isthreaded())
273		exit(0);
274
275	if (atomic_fetchadd_int(&_thread_active_threads, -1) == 1) {
276		exit(0);
277		/* Never reach! */
278	}
279
280	/* Tell malloc that the thread is exiting. */
281	_malloc_thread_cleanup();
282
283	THR_LOCK(curthread);
284	curthread->state = PS_DEAD;
285	if (curthread->flags & THR_FLAGS_NEED_SUSPEND) {
286		curthread->cycle++;
287		_thr_umtx_wake(&curthread->cycle, INT_MAX, 0);
288	}
289	if (!curthread->force_exit && SHOULD_REPORT_EVENT(curthread, TD_DEATH))
290		_thr_report_death(curthread);
291	/*
292	 * Thread was created with initial refcount 1, we drop the
293	 * reference count to allow it to be garbage collected.
294	 */
295	curthread->refcount--;
296	_thr_try_gc(curthread, curthread); /* thread lock released */
297
298#if defined(_PTHREADS_INVARIANTS)
299	if (THR_IN_CRITICAL(curthread))
300		PANIC("thread exits with resources held!");
301#endif
302	/*
303	 * Kernel will do wakeup at the address, so joiner thread
304	 * will be resumed if it is sleeping at the address.
305	 */
306	thr_exit(&curthread->tid);
307	PANIC("thr_exit() returned");
308	/* Never reach! */
309}
310