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freebsd-dev/lib/libthr/thread/thr_exit.c

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- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
/*
* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include "thr_private.h"
__weak_reference(_pthread_exit, pthread_exit);
Make WARNS2 clean. The fixes mostly included: o removed unused variables o explicit inclusion of header files o prototypes for externally defined functions Approved by: re/blanket libthr
2003-05-23 09:48:20 +00:00
/* thr_exit() */
extern int _thr_exit(void);
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
void
_thread_exit(char *fname, int lineno, char *string)
{
char s[256];
/* Prepare an error message string: */
snprintf(s, sizeof(s),
"Fatal error '%s' at line %d in file %s (errno = %d)\n",
string, lineno, fname, errno);
/* Write the string to the standard error file descriptor: */
__sys_write(2, s, strlen(s));
/* Force this process to exit: */
/* XXX - Do we want abort to be conditional on _PTHREADS_INVARIANTS? */
#if defined(_PTHREADS_INVARIANTS)
abort();
#else
__sys_exit(1);
#endif
}
/*
* Only called when a thread is cancelled. It may be more useful
* to call it from pthread_exit() if other ways of asynchronous or
* abnormal thread termination can be found.
*/
void
_thread_exit_cleanup(void)
{
/*
* POSIX states that cancellation/termination of a thread should
* not release any visible resources (such as mutexes) and that
* it is the applications responsibility. Resources that are
* internal to the threads library, including file and fd locks,
* are not visible to the application and need to be released.
*/
/* Unlock all private mutexes: */
_mutex_unlock_private(curthread);
/*
* This still isn't quite correct because we don't account
* for held spinlocks (see libc/stdlib/malloc.c).
*/
}
void
_pthread_exit(void *status)
{
Minimize the potential for deadlocks between an exiting thread and it's joiner by making sure all locks and unlocks occur in the same order. For the record the lock order is: DEAD_LIST, THREAD_LIST, exiting thread, joiner thread. Approved by: re/rwatson
2003-05-27 21:48:42 +00:00
pthread_t pthread, joiner;
Start locking up the active and dead threads lists. The active threads list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
2003-05-25 08:31:33 +00:00
int exitNow = 0;
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
/* Check if this thread is already in the process of exiting: */
if ((curthread->flags & PTHREAD_EXITING) != 0) {
char msg[128];
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);
PANIC(msg);
}
/* Flag this thread as exiting: */
curthread->flags |= PTHREAD_EXITING;
/* Save the return value: */
curthread->ret = status;
while (curthread->cleanup != NULL) {
pthread_cleanup_pop(1);
}
if (curthread->attr.cleanup_attr != NULL) {
curthread->attr.cleanup_attr(curthread->attr.arg_attr);
}
/* Check if there is thread specific data: */
if (curthread->specific != NULL) {
/* Run the thread-specific data destructors: */
_thread_cleanupspecific();
}
Minimize the potential for deadlocks between an exiting thread and it's joiner by making sure all locks and unlocks occur in the same order. For the record the lock order is: DEAD_LIST, THREAD_LIST, exiting thread, joiner thread. Approved by: re/rwatson
2003-05-27 21:48:42 +00:00
retry:
/*
* Proper lock order, to minimize deadlocks, between joining
* and exiting threads is: DEAD_LIST, THREAD_LIST, exiting, joiner.
* In order to do this *and* protect from races, we must resort
* this test-and-retry loop.
*/
joiner = curthread->joiner;
Start locking up the active and dead threads lists. The active threads list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
2003-05-25 08:31:33 +00:00
/* Lock the dead list first to maintain correct lock order */
DEAD_LIST_LOCK;
Minimize the potential for deadlocks between an exiting thread and it's joiner by making sure all locks and unlocks occur in the same order. For the record the lock order is: DEAD_LIST, THREAD_LIST, exiting thread, joiner thread. Approved by: re/rwatson
2003-05-27 21:48:42 +00:00
THREAD_LIST_LOCK;
Start locking up the active and dead threads lists. The active threads list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
2003-05-25 08:31:33 +00:00
_thread_critical_enter(curthread);
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
Minimize the potential for deadlocks between an exiting thread and it's joiner by making sure all locks and unlocks occur in the same order. For the record the lock order is: DEAD_LIST, THREAD_LIST, exiting thread, joiner thread. Approved by: re/rwatson
2003-05-27 21:48:42 +00:00
if (joiner != curthread->joiner) {
_thread_critical_exit(curthread);
THREAD_LIST_UNLOCK;
DEAD_LIST_UNLOCK;
goto retry;
}
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
/* Check if there is a thread joining this one: */
if (curthread->joiner != NULL) {
pthread = curthread->joiner;
Change all instances of THR_LOCK/UNLOCK, etc to UMTX_*. It is a more acurate description of the locks they operate on.
2003-07-06 10:18:48 +00:00
UMTX_LOCK(&pthread->lock);
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
curthread->joiner = NULL;
/* Make the joining thread runnable: */
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
/* Set the return value for the joining thread: */
pthread->join_status.ret = curthread->ret;
pthread->join_status.error = 0;
pthread->join_status.thread = NULL;
Change all instances of THR_LOCK/UNLOCK, etc to UMTX_*. It is a more acurate description of the locks they operate on.
2003-07-06 10:18:48 +00:00
UMTX_UNLOCK(&pthread->lock);
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
/* Make this thread collectable by the garbage collector. */
PTHREAD_ASSERT(((curthread->attr.flags & PTHREAD_DETACHED) ==
0), "Cannot join a detached thread");
curthread->attr.flags |= PTHREAD_DETACHED;
}
Start locking up the active and dead threads lists. The active threads list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
2003-05-25 08:31:33 +00:00
/*
* Add this thread to the list of dead threads, and
* also remove it from the active threads list.
*/
TAILQ_INSERT_HEAD(&_dead_list, curthread, dle);
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
TAILQ_REMOVE(&_thread_list, curthread, tle);
PTHREAD_SET_STATE(curthread, PS_DEAD);
Start locking up the active and dead threads lists. The active threads list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
2003-05-25 08:31:33 +00:00
_thread_critical_exit(curthread);
When a thread exits it does not return from the kernel unless it is the *only* remaining thread in the application, in which case we should not core dump, and instead exit gracefully. Approved by: markm/mentor, re/blanket libthr
2003-05-21 03:29:18 +00:00
/* If we're the last thread, call it quits */
if (TAILQ_EMPTY(&_thread_list))
Start locking up the active and dead threads lists. The active threads list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
2003-05-25 08:31:33 +00:00
exitNow = 1;
THREAD_LIST_UNLOCK;
Don't hold the active thread list lock when signaling the gc thread. The dead list thread is sufficient for synchronization. Retire the arch_id (ldt array slot) in the gc thread instead of the doing it in the thread itself. Approved by: re/jhb
2003-05-29 20:46:53 +00:00
/*
* Signal the garbage collector thread that there is something
* to clean up. But don't allow it to free the memory until after
* it is retired by holding on to the dead list lock.
*/
if (pthread_cond_signal(&_gc_cond) != 0)
PANIC("Cannot signal gc cond");
Start locking up the active and dead threads lists. The active threads list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
2003-05-25 08:31:33 +00:00
if (exitNow)
note to self: do not confuse void* with int. Approved by: re/blanket libthr
2003-05-23 08:13:24 +00:00
exit(0);
When a thread exits it does not return from the kernel unless it is the *only* remaining thread in the application, in which case we should not core dump, and instead exit gracefully. Approved by: markm/mentor, re/blanket libthr
2003-05-21 03:29:18 +00:00
Don't hold the active thread list lock when signaling the gc thread. The dead list thread is sufficient for synchronization. Retire the arch_id (ldt array slot) in the gc thread instead of the doing it in the thread itself. Approved by: re/jhb
2003-05-29 20:46:53 +00:00
DEAD_LIST_UNLOCK;
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
/*
Don't hold the active thread list lock when signaling the gc thread. The dead list thread is sufficient for synchronization. Retire the arch_id (ldt array slot) in the gc thread instead of the doing it in the thread itself. Approved by: re/jhb
2003-05-29 20:46:53 +00:00
* This function will not return unless we are the last
* thread, which we can't be because we've already checked
* for that.
- Add libthr but don't hook it up to the regular build yet. This is an adaptation of libc_r for the thr system call interface. This is beta quality code.
2003-04-01 03:46:29 +00:00
*/
_thr_exit();
/* This point should not be reached. */
PANIC("Dead thread has resumed");
}
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