/* * 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_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_MONOTONICextern unsigned long long monotonic_clock(void);#elsestatic 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);