1/* 2 * hangcheck-timer.c 3 * 4 * Driver for a little io fencing timer. 5 * 6 * Copyright (C) 2002, 2003 Oracle. All rights reserved. 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 parameter 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> 47#include <linux/init.h> 48#include <linux/delay.h> 49#include <asm/uaccess.h> 50#include <linux/sysrq.h> 51#include <linux/timer.h> 52#include <linux/time.h> 53 54#define VERSION_STR "0.9.1" 55 56#define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */ 57#define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */ 58 59static int hangcheck_tick = DEFAULT_IOFENCE_TICK; 60static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN; 61static int hangcheck_reboot; /* Defaults to not reboot */ 62static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */ 63 64/* options - modular */ 65module_param(hangcheck_tick, int, 0); 66MODULE_PARM_DESC(hangcheck_tick, "Timer delay."); 67module_param(hangcheck_margin, int, 0); 68MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire."); 69module_param(hangcheck_reboot, int, 0); 70MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded."); 71module_param(hangcheck_dump_tasks, int, 0); 72MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded."); 73 74MODULE_AUTHOR("Oracle"); 75MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin."); 76MODULE_LICENSE("GPL"); 77MODULE_VERSION(VERSION_STR); 78 79/* options - nonmodular */ 80#ifndef MODULE 81 82static 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 90static 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 98static 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 106static 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 */ 119 120#if defined(CONFIG_S390) 121# define HAVE_MONOTONIC 122# define TIMER_FREQ 1000000000ULL 123#else 124# define TIMER_FREQ 1000000000ULL 125#endif 126 127#ifdef HAVE_MONOTONIC 128extern unsigned long long monotonic_clock(void); 129#else 130static inline unsigned long long monotonic_clock(void) 131{ 132 struct timespec ts; 133 getrawmonotonic(&ts); 134 return timespec_to_ns(&ts); 135} 136#endif /* HAVE_MONOTONIC */ 137 138 139/* Last time scheduled */ 140static unsigned long long hangcheck_tsc, hangcheck_tsc_margin; 141 142static void hangcheck_fire(unsigned long); 143 144static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0); 145 146 147static 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) { 159 if (hangcheck_dump_tasks) { 160 printk(KERN_CRIT "Hangcheck: Task state:\n"); 161#ifdef CONFIG_MAGIC_SYSRQ 162 handle_sysrq('t'); 163#endif /* CONFIG_MAGIC_SYSRQ */ 164 } 165 if (hangcheck_reboot) { 166 printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n"); 167 emergency_restart(); 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 177static 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); 181#if defined(HAVE_MONOTONIC) 182 printk("Hangcheck: Using monotonic_clock().\n"); 183#else 184 printk("Hangcheck: Using getrawmonotonic().\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; 189 190 hangcheck_tsc = monotonic_clock(); 191 mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); 192 193 return 0; 194} 195 196 197static void __exit hangcheck_exit(void) 198{ 199 del_timer_sync(&hangcheck_ticktock); 200 printk("Hangcheck: Stopped hangcheck timer.\n"); 201} 202 203module_init(hangcheck_init); 204module_exit(hangcheck_exit); 205