linux-imx

/*

 * hangcheck-timer.c

 *

 * Driver for a little io fencing timer.

 *

 * Copyright (C) 2002, 2003 Oracle.  All rights reserved.

 *

 * Author: Joel Becker <joel.becker@oracle.com>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public

 * License version 2 as published by the Free Software Foundation.

 * 

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 * 

 * You should have received a copy of the GNU General Public

 * License along with this program; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 021110-1307, USA.

 */

​

/*

 * The hangcheck-timer driver uses the TSC to catch delays that

 * jiffies does not notice.  A timer is set.  When the timer fires, it

 * checks whether it was delayed and if that delay exceeds a given

 * margin of error.  The hangcheck_tick module parameter takes the timer

 * duration in seconds.  The hangcheck_margin parameter defines the

 * margin of error, in seconds.  The defaults are 60 seconds for the

 * timer and 180 seconds for the margin of error.  IOW, a timer is set

 * for 60 seconds.  When the timer fires, the callback checks the

 * actual duration that the timer waited.  If the duration exceeds the

 * allotted time and margin (here 60 + 180, or 240 seconds), the machine

 * is restarted.  A healthy machine will have the duration match the

 * expected timeout very closely.

 */

​

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/fs.h>

#include <linux/mm.h>

#include <linux/reboot.h>

#include <linux/init.h>

#include <linux/delay.h>

#include <linux/uaccess.h>

#include <linux/sysrq.h>

#include <linux/timer.h>

#include <linux/hrtimer.h>

​

#define VERSION_STR "0.9.1"

​

#define DEFAULT_IOFENCE_MARGIN 60   /* Default fudge factor, in seconds */

#define DEFAULT_IOFENCE_TICK 180    /* Default timer timeout, in seconds */

​

static int hangcheck_tick = DEFAULT_IOFENCE_TICK;

static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN;

static int hangcheck_reboot;  /* Defaults to not reboot */

static int hangcheck_dump_tasks;  /* Defaults to not dumping SysRQ T */

​