[net-next-2.6.git] / drivers / char / hangcheck-timer.c

/*
 * 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 paramter 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
 * alloted 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/smp_lock.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <linux/sysrq.h>


#define VERSION_STR "0.9.0"

#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 */

/* options - modular */
module_param(hangcheck_tick, int, 0);
MODULE_PARM_DESC(hangcheck_tick, "Timer delay.");
module_param(hangcheck_margin, int, 0);
MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire.");
module_param(hangcheck_reboot, int, 0);
MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded.");
module_param(hangcheck_dump_tasks, int, 0);
MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded.");

MODULE_AUTHOR("Oracle");
MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin.");
MODULE_LICENSE("GPL");
MODULE_VERSION(VERSION_STR);

/* options - nonmodular */
#ifndef MODULE

static int __init hangcheck_parse_tick(char *str)
{
	int par;
	if (get_option(&str,&par))
		hangcheck_tick = par;
	return 1;
}

static int __init hangcheck_parse_margin(char *str)
{
	int par;
	if (get_option(&str,&par))
		hangcheck_margin = par;
	return 1;
}

static int __init hangcheck_parse_reboot(char *str)
{
	int par;
	if (get_option(&str,&par))
		hangcheck_reboot = par;
	return 1;
}

static int __init hangcheck_parse_dump_tasks(char *str)
{
	int par;
	if (get_option(&str,&par))
		hangcheck_dump_tasks = par;
	return 1;
}

__setup("hcheck_tick", hangcheck_parse_tick);
__setup("hcheck_margin", hangcheck_parse_margin);
__setup("hcheck_reboot", hangcheck_parse_reboot);
__setup("hcheck_dump_tasks", hangcheck_parse_dump_tasks);
#endif /* not MODULE */

#if defined(CONFIG_X86_64) || defined(CONFIG_S390)
# define HAVE_MONOTONIC
# define TIMER_FREQ 1000000000ULL
#elif defined(CONFIG_IA64)
# define TIMER_FREQ ((unsigned long long)local_cpu_data->itc_freq)
#else
# define TIMER_FREQ (HZ*loops_per_jiffy)
#endif

#ifdef HAVE_MONOTONIC
extern unsigned long long monotonic_clock(void);
#else
static inline unsigned long long monotonic_clock(void)
{
	return get_cycles();
}
#endif  /* HAVE_MONOTONIC */


/* Last time scheduled */
static unsigned long long hangcheck_tsc, hangcheck_tsc_margin;

static void hangcheck_fire(unsigned long);

static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0);


static void hangcheck_fire(unsigned long data)
{
	unsigned long long cur_tsc, tsc_diff;

	cur_tsc = monotonic_clock();

	if (cur_tsc > hangcheck_tsc)
		tsc_diff = cur_tsc - hangcheck_tsc;
	else
		tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */

	if (tsc_diff > hangcheck_tsc_margin) {
		if (hangcheck_dump_tasks) {
			printk(KERN_CRIT "Hangcheck: Task state:\n");
#ifdef CONFIG_MAGIC_SYSRQ
			handle_sysrq('t', NULL);
#endif  /* CONFIG_MAGIC_SYSRQ */
		}
		if (hangcheck_reboot) {
			printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n");
			emergency_restart();
		} else {
			printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n");
		}
	}
	mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
	hangcheck_tsc = monotonic_clock();
}


static int __init hangcheck_init(void)
{
	printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
	       VERSION_STR, hangcheck_tick, hangcheck_margin);
#if defined (HAVE_MONOTONIC)
	printk("Hangcheck: Using monotonic_clock().\n");
#else
	printk("Hangcheck: Using get_cycles().\n");
#endif  /* HAVE_MONOTONIC */
	hangcheck_tsc_margin =
		(unsigned long long)(hangcheck_margin + hangcheck_tick);
	hangcheck_tsc_margin *= (unsigned long long)TIMER_FREQ;

	hangcheck_tsc = monotonic_clock();
	mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));

	return 0;
}


static void __exit hangcheck_exit(void)
{
	del_timer_sync(&hangcheck_ticktock);
        printk("Hangcheck: Stopped hangcheck timer.\n");
}

module_init(hangcheck_init);
module_exit(hangcheck_exit);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* hangcheck-timer.c
	3	*
	4	* Driver for a little io fencing timer.
	5	*
696f9486	6	* Copyright (C) 2002, 2003 Oracle. All rights reserved.
1da177e4 LT	7	*
	8	* Author: Joel Becker <joel.becker@oracle.com>
	9	*
	10	* This program is free software; you can redistribute it and/or
	11	* modify it under the terms of the GNU General Public
	12	* License version 2 as published by the Free Software Foundation.
	13	*
	14	* This program is distributed in the hope that it will be useful,
	15	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU General Public
	20	* License along with this program; if not, write to the
	21	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	22	* Boston, MA 021110-1307, USA.
	23	*/
	24
	25	/*
	26	* The hangcheck-timer driver uses the TSC to catch delays that
	27	* jiffies does not notice. A timer is set. When the timer fires, it
	28	* checks whether it was delayed and if that delay exceeds a given
	29	* margin of error. The hangcheck_tick module paramter takes the timer
	30	* duration in seconds. The hangcheck_margin parameter defines the
	31	* margin of error, in seconds. The defaults are 60 seconds for the
	32	* timer and 180 seconds for the margin of error. IOW, a timer is set
	33	* for 60 seconds. When the timer fires, the callback checks the
	34	* actual duration that the timer waited. If the duration exceeds the
	35	* alloted time and margin (here 60 + 180, or 240 seconds), the machine
	36	* is restarted. A healthy machine will have the duration match the
	37	* expected timeout very closely.
	38	*/
	39
	40	#include <linux/module.h>
	41	#include <linux/moduleparam.h>
	42	#include <linux/types.h>
	43	#include <linux/kernel.h>
	44	#include <linux/fs.h>
	45	#include <linux/mm.h>
	46	#include <linux/reboot.h>
696f9486	47	#include <linux/smp_lock.h>
1da177e4	48	#include <linux/init.h>
696f9486	49	#include <linux/delay.h>
1da177e4	50	#include <asm/uaccess.h>
696f9486	51	#include <linux/sysrq.h>
1da177e4 LT	52
1da177e4 LT	53
696f9486	54	#define VERSION_STR "0.9.0"
1da177e4 LT	55
	56	#define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */
	57	#define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */
	58
	59	static int hangcheck_tick = DEFAULT_IOFENCE_TICK;
	60	static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN;
	61	static int hangcheck_reboot; /* Defaults to not reboot */
696f9486	62	static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */
1da177e4	63
696f9486	64	/* options - modular */
1da177e4 LT	65	module_param(hangcheck_tick, int, 0);
	66	MODULE_PARM_DESC(hangcheck_tick, "Timer delay.");
	67	module_param(hangcheck_margin, int, 0);
	68	MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire.");
	69	module_param(hangcheck_reboot, int, 0);
	70	MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded.");
696f9486 JB	71	module_param(hangcheck_dump_tasks, int, 0);
696f9486 JB	72	MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded.");
1da177e4	73
696f9486	74	MODULE_AUTHOR("Oracle");
1da177e4 LT	75	MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin.");
1da177e4 LT	76	MODULE_LICENSE("GPL");
696f9486 JB	77	MODULE_VERSION(VERSION_STR);
	78
	79	/* options - nonmodular */
	80	#ifndef MODULE
	81
	82	static int __init hangcheck_parse_tick(char *str)
	83	{
	84	int par;
	85	if (get_option(&str,&par))
	86	hangcheck_tick = par;
	87	return 1;
	88	}
	89
	90	static int __init hangcheck_parse_margin(char *str)
	91	{
	92	int par;
	93	if (get_option(&str,&par))
	94	hangcheck_margin = par;
	95	return 1;
	96	}
	97
	98	static int __init hangcheck_parse_reboot(char *str)
	99	{
	100	int par;
	101	if (get_option(&str,&par))
	102	hangcheck_reboot = par;
	103	return 1;
	104	}
	105
	106	static int __init hangcheck_parse_dump_tasks(char *str)
	107	{
	108	int par;
	109	if (get_option(&str,&par))
	110	hangcheck_dump_tasks = par;
	111	return 1;
	112	}
	113
	114	__setup("hcheck_tick", hangcheck_parse_tick);
	115	__setup("hcheck_margin", hangcheck_parse_margin);
	116	__setup("hcheck_reboot", hangcheck_parse_reboot);
	117	__setup("hcheck_dump_tasks", hangcheck_parse_dump_tasks);
	118	#endif /* not MODULE */
	119
ede65f39	120	#if defined(CONFIG_X86_64) \|\| defined(CONFIG_S390)
696f9486 JB	121	# define HAVE_MONOTONIC
696f9486 JB	122	# define TIMER_FREQ 1000000000ULL
696f9486 JB	123	#elif defined(CONFIG_IA64)
696f9486 JB	124	# define TIMER_FREQ ((unsigned long long)local_cpu_data->itc_freq)
ede65f39	125	#else
696f9486 JB	126	# define TIMER_FREQ (HZ*loops_per_jiffy)
	127	#endif
	128
	129	#ifdef HAVE_MONOTONIC
	130	extern unsigned long long monotonic_clock(void);
	131	#else
	132	static inline unsigned long long monotonic_clock(void)
	133	{
696f9486	134	return get_cycles();
696f9486 JB	135	}
696f9486 JB	136	#endif /* HAVE_MONOTONIC */
1da177e4 LT	137
	138
	139	/* Last time scheduled */
	140	static unsigned long long hangcheck_tsc, hangcheck_tsc_margin;
	141
	142	static void hangcheck_fire(unsigned long);
	143
8d06afab	144	static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0);
1da177e4	145
1da177e4 LT	146
	147	static void hangcheck_fire(unsigned long data)
	148	{
	149	unsigned long long cur_tsc, tsc_diff;
	150
	151	cur_tsc = monotonic_clock();
	152
	153	if (cur_tsc > hangcheck_tsc)
	154	tsc_diff = cur_tsc - hangcheck_tsc;
	155	else
	156	tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */
	157
	158	if (tsc_diff > hangcheck_tsc_margin) {
696f9486 JB	159	if (hangcheck_dump_tasks) {
	160	printk(KERN_CRIT "Hangcheck: Task state:\n");
	161	#ifdef CONFIG_MAGIC_SYSRQ
7d12e780	162	handle_sysrq('t', NULL);
696f9486 JB	163	#endif /* CONFIG_MAGIC_SYSRQ */
696f9486 JB	164	}
1da177e4 LT	165	if (hangcheck_reboot) {
1da177e4 LT	166	printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n");
970d3244	167	emergency_restart();
1da177e4 LT	168	} else {
	169	printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n");
	170	}
	171	}
	172	mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
	173	hangcheck_tsc = monotonic_clock();
	174	}
	175
	176
	177	static int __init hangcheck_init(void)
	178	{
	179	printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
	180	VERSION_STR, hangcheck_tick, hangcheck_margin);
696f9486 JB	181	#if defined (HAVE_MONOTONIC)
696f9486 JB	182	printk("Hangcheck: Using monotonic_clock().\n");
696f9486 JB	183	#else
	184	printk("Hangcheck: Using get_cycles().\n");
	185	#endif /* HAVE_MONOTONIC */
	186	hangcheck_tsc_margin =
	187	(unsigned long long)(hangcheck_margin + hangcheck_tick);
	188	hangcheck_tsc_margin *= (unsigned long long)TIMER_FREQ;
1da177e4 LT	189
	190	hangcheck_tsc = monotonic_clock();
	191	mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
	192
	193	return 0;
	194	}
	195
	196
	197	static void __exit hangcheck_exit(void)
	198	{
	199	del_timer_sync(&hangcheck_ticktock);
696f9486	200	printk("Hangcheck: Stopped hangcheck timer.\n");
1da177e4 LT	201	}
	202
	203	module_init(hangcheck_init);
	204	module_exit(hangcheck_exit);