df42f1ac5f
the thread kernel into a garbage collector thread which is started when the fisrt thread is created (other than the initial thread). This removes the window of opportunity where a context switch will cause a thread that has locked the malloc spinlock, to enter the thread kernel, find there is a dead thread and try to free memory, therefore trying to lock the malloc spinlock against itself. The garbage collector thread acts just like any other thread, so instead of having a spinlock to control accesses to the dead thread list, it uses a mutex and a condition variable so that it can happily wait to be signalled when a thread exists.
103 lines
3.4 KiB
C
103 lines
3.4 KiB
C
/*
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* Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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#include <errno.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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/* Find a thread in the linked list of active threads: */
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int
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_find_thread(pthread_t pthread)
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{
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pthread_t pthread1;
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/* Check if the caller has specified an invalid thread: */
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if (pthread == NULL || pthread->magic != PTHREAD_MAGIC)
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/* Invalid thread: */
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return(EINVAL);
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/* Lock the thread list: */
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_lock_thread_list();
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/* Point to the first thread in the list: */
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pthread1 = _thread_link_list;
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/* Search for the thread to join to: */
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while (pthread1 != NULL && pthread1 != pthread) {
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/* Point to the next thread: */
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pthread1 = pthread1->nxt;
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}
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/* Unlock the thread list: */
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_unlock_thread_list();
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/* Return zero if the thread exists: */
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return ((pthread1 != NULL) ? 0:ESRCH);
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}
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/* Find a thread in the linked list of dead threads: */
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int
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_find_dead_thread(pthread_t pthread)
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{
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pthread_t pthread1;
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/* Check if the caller has specified an invalid thread: */
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if (pthread == NULL || pthread->magic != PTHREAD_MAGIC)
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/* Invalid thread: */
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return(EINVAL);
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/*
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* Lock the garbage collector mutex to ensure that the garbage
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* collector is not using the dead thread list.
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*/
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if (pthread_mutex_lock(&_gc_mutex) != 0)
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PANIC("Cannot lock gc mutex");
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/* Point to the first thread in the list: */
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pthread1 = _thread_dead;
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/* Search for the thread to join to: */
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while (pthread1 != NULL && pthread1 != pthread) {
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/* Point to the next thread: */
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pthread1 = pthread1->nxt_dead;
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}
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/* Unlock the garbage collector mutex: */
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if (pthread_mutex_unlock(&_gc_mutex) != 0)
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PANIC("Cannot lock gc mutex");
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/* Return zero if the thread exists: */
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return ((pthread1 != NULL) ? 0:ESRCH);
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}
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#endif
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