dc3a8b52c0
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.
165 lines
5.1 KiB
C
165 lines
5.1 KiB
C
/*
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* Copyright (c) 1995-1998 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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#include <unistd.h>
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#include <fcntl.h>
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#include <string.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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void _exit(int status)
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{
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int flags;
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int i;
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struct itimerval itimer;
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/* Disable the interval timer: */
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itimer.it_interval.tv_sec = 0;
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itimer.it_interval.tv_usec = 0;
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itimer.it_value.tv_sec = 0;
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itimer.it_value.tv_usec = 0;
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setitimer(ITIMER_VIRTUAL, &itimer, NULL);
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/* Close the pthread kernel pipe: */
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_thread_sys_close(_thread_kern_pipe[0]);
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_thread_sys_close(_thread_kern_pipe[1]);
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/*
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* Enter a loop to set all file descriptors to blocking
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* if they were not created as non-blocking:
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*/
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for (i = 0; i < _thread_dtablesize; i++) {
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/* Check if this file descriptor is in use: */
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if (_thread_fd_table[i] != NULL &&
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!(_thread_fd_table[i]->flags & O_NONBLOCK)) {
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/* Get the current flags: */
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flags = _thread_sys_fcntl(i, F_GETFL, NULL);
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/* Clear the nonblocking file descriptor flag: */
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_thread_sys_fcntl(i, F_SETFL, flags & ~O_NONBLOCK);
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}
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}
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/* Call the _exit syscall: */
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_thread_sys__exit(status);
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}
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void
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_thread_exit(char *fname, int lineno, char *string)
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{
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char s[256];
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/* Prepare an error message string: */
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strcpy(s, "Fatal error '");
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strcat(s, string);
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strcat(s, "' at line ? ");
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strcat(s, "in file ");
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strcat(s, fname);
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strcat(s, " (errno = ?");
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strcat(s, ")\n");
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/* Write the string to the standard error file descriptor: */
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_thread_sys_write(2, s, strlen(s));
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/* Force this process to exit: */
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_exit(1);
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}
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void
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pthread_exit(void *status)
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{
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int sig;
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long l;
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pthread_t pthread;
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/* Check if this thread is already in the process of exiting: */
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if ((_thread_run->flags & PTHREAD_EXITING) != 0) {
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char msg[128];
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snprintf(msg,"Thread %p has called pthread_exit() from a destructor. POSIX 1003.1 1996 s16.2.5.2 does not allow this!",_thread_run);
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PANIC(msg);
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}
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/* Flag this thread as exiting: */
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_thread_run->flags |= PTHREAD_EXITING;
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/* Save the return value: */
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_thread_run->ret = status;
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while (_thread_run->cleanup != NULL) {
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pthread_cleanup_pop(1);
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}
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if (_thread_run->attr.cleanup_attr != NULL) {
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_thread_run->attr.cleanup_attr(_thread_run->attr.arg_attr);
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}
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/* Check if there is thread specific data: */
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if (_thread_run->specific_data != NULL) {
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/* Run the thread-specific data destructors: */
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_thread_cleanupspecific();
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}
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/* Check if there are any threads joined to this one: */
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while ((pthread = _thread_queue_deq(&(_thread_run->join_queue))) != NULL) {
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/* Wake the joined thread and let it detach this thread: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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}
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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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/* Add this thread to the list of dead threads. */
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_thread_run->nxt_dead = _thread_dead;
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_thread_dead = _thread_run;
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/*
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* Signal the garbage collector thread that there is something
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* to clean up.
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*/
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if (pthread_cond_signal(&_gc_cond) != 0)
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PANIC("Cannot signal gc cond");
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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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/* This this thread will never be re-scheduled. */
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_thread_kern_sched_state(PS_DEAD, __FILE__, __LINE__);
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/* This point should not be reached. */
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PANIC("Dead thread has resumed");
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}
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#endif
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