freebsd-dev/lib/libthr/thread/thr_info.c
Mike Makonnen 71d09bc86a 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

195 lines
5.7 KiB
C

/*
* 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 <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <errno.h>
#include "thr_private.h"
#ifndef NELEMENTS
#define NELEMENTS(arr) (sizeof(arr) / sizeof(arr[0]))
#endif
static void dump_thread(int fd, pthread_t pthread, int long_version);
__weak_reference(_pthread_set_name_np, pthread_set_name_np);
struct s_thread_info {
enum pthread_state state;
char *name;
};
/* Static variables: */
static const struct s_thread_info thread_info[] = {
{PS_RUNNING , "Running"},
{PS_MUTEX_WAIT , "Waiting on a mutex"},
{PS_COND_WAIT , "Waiting on a condition variable"},
{PS_SLEEP_WAIT , "Sleeping"},
{PS_WAIT_WAIT , "Waiting process"},
{PS_JOIN , "Waiting to join"},
{PS_DEAD , "Dead"},
{PS_DEADLOCK , "Deadlocked"},
{PS_STATE_MAX , "Not a real state!"}
};
void
_thread_dump_info(void)
{
char s[512];
int fd;
int i;
pthread_t pthread;
char tmpfile[128];
for (i = 0; i < 100000; i++) {
snprintf(tmpfile, sizeof(tmpfile), "/tmp/uthread.dump.%u.%i",
getpid(), i);
/* Open the dump file for append and create it if necessary: */
if ((fd = __sys_open(tmpfile, O_RDWR | O_CREAT | O_EXCL,
0666)) < 0) {
/* Can't open the dump file. */
if (errno == EEXIST)
continue;
/*
* We only need to continue in case of
* EEXIT error. Most other error
* codes means that we will fail all
* the times.
*/
return;
} else {
break;
}
}
if (i==100000) {
/* all 100000 possibilities are in use :( */
return;
} else {
/* Output a header for active threads: */
strcpy(s, "\n\n=============\nACTIVE THREADS\n\n");
__sys_write(fd, s, strlen(s));
/* Enter a loop to report each thread in the global list: */
TAILQ_FOREACH(pthread, &_thread_list, tle) {
dump_thread(fd, pthread, /*long_verson*/ 1);
}
/* Check if there are no dead threads: */
DEAD_LIST_LOCK;
if (TAILQ_FIRST(&_dead_list) == NULL) {
/* Output a record: */
strcpy(s, "\n\nTHERE ARE NO DEAD THREADS\n");
__sys_write(fd, s, strlen(s));
} else {
/* Output a header for dead threads: */
strcpy(s, "\n\nDEAD THREADS\n\n");
__sys_write(fd, s, strlen(s));
/*
* Enter a loop to report each thread in the global
* dead thread list:
*/
TAILQ_FOREACH(pthread, &_dead_list, dle) {
dump_thread(fd, pthread, /*long_version*/ 0);
}
}
DEAD_LIST_UNLOCK;
/* Close the dump file: */
__sys_close(fd);
}
}
static void
dump_thread(int fd, pthread_t pthread, int long_version)
{
char s[512];
int i;
/* Find the state: */
for (i = 0; i < NELEMENTS(thread_info) - 1; i++)
if (thread_info[i].state == pthread->state)
break;
/* Output a record for the thread: */
snprintf(s, sizeof(s),
"--------------------\nThread %p (%s) prio %3d state %s [%s:%d]\n",
pthread, (pthread->name == NULL) ? "" : pthread->name,
pthread->active_priority, thread_info[i].name, pthread->fname,
pthread->lineno);
__sys_write(fd, s, strlen(s));
if (long_version != 0) {
/* Check if this is the running thread: */
if (pthread == curthread) {
/* Output a record for the running thread: */
strcpy(s, "This is the running thread\n");
__sys_write(fd, s, strlen(s));
}
/* Check if this is the initial thread: */
if (pthread == _thread_initial) {
/* Output a record for the initial thread: */
strcpy(s, "This is the initial thread\n");
__sys_write(fd, s, strlen(s));
}
/* Process according to thread state: */
switch (pthread->state) {
/*
* Trap other states that are not explicitly
* coded to dump information:
*/
default:
/* Nothing to do here. */
break;
}
}
}
/* Set the thread name for debug: */
void
_pthread_set_name_np(pthread_t thread, const char *name)
{
/* Check if the caller has specified a valid thread: */
if (thread != NULL && thread->magic == PTHREAD_MAGIC) {
if (thread->name != NULL) {
/* Free space for previous name. */
free(thread->name);
}
thread->name = strdup(name);
}
}