| 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 | |
| 53 | #define VERSION_STR "0.9.0" |
| 54 | |
| 55 | #define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */ |
| 56 | #define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */ |
| 57 | |
| 58 | static int hangcheck_tick = DEFAULT_IOFENCE_TICK; |
| 59 | static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN; |
| 60 | static int hangcheck_reboot; /* Defaults to not reboot */ |
| 61 | static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */ |
| 62 | |
| 63 | /* options - modular */ |
| 64 | module_param(hangcheck_tick, int, 0); |
| 65 | MODULE_PARM_DESC(hangcheck_tick, "Timer delay."); |
| 66 | module_param(hangcheck_margin, int, 0); |
| 67 | MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire."); |
| 68 | module_param(hangcheck_reboot, int, 0); |
| 69 | MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded."); |
| 70 | module_param(hangcheck_dump_tasks, int, 0); |
| 71 | MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded."); |
| 72 | |
| 73 | MODULE_AUTHOR("Oracle"); |
| 74 | MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin."); |
| 75 | MODULE_LICENSE("GPL"); |
| 76 | MODULE_VERSION(VERSION_STR); |
| 77 | |
| 78 | /* options - nonmodular */ |
| 79 | #ifndef MODULE |
| 80 | |
| 81 | static int __init hangcheck_parse_tick(char *str) |
| 82 | { |
| 83 | int par; |
| 84 | if (get_option(&str,&par)) |
| 85 | hangcheck_tick = par; |
| 86 | return 1; |
| 87 | } |
| 88 | |
| 89 | static int __init hangcheck_parse_margin(char *str) |
| 90 | { |
| 91 | int par; |
| 92 | if (get_option(&str,&par)) |
| 93 | hangcheck_margin = par; |
| 94 | return 1; |
| 95 | } |
| 96 | |
| 97 | static int __init hangcheck_parse_reboot(char *str) |
| 98 | { |
| 99 | int par; |
| 100 | if (get_option(&str,&par)) |
| 101 | hangcheck_reboot = par; |
| 102 | return 1; |
| 103 | } |
| 104 | |
| 105 | static int __init hangcheck_parse_dump_tasks(char *str) |
| 106 | { |
| 107 | int par; |
| 108 | if (get_option(&str,&par)) |
| 109 | hangcheck_dump_tasks = par; |
| 110 | return 1; |
| 111 | } |
| 112 | |
| 113 | __setup("hcheck_tick", hangcheck_parse_tick); |
| 114 | __setup("hcheck_margin", hangcheck_parse_margin); |
| 115 | __setup("hcheck_reboot", hangcheck_parse_reboot); |
| 116 | __setup("hcheck_dump_tasks", hangcheck_parse_dump_tasks); |
| 117 | #endif /* not MODULE */ |
| 118 | |
| 119 | #if defined(CONFIG_S390) |
| 120 | # define HAVE_MONOTONIC |
| 121 | # define TIMER_FREQ 1000000000ULL |
| 122 | #elif defined(CONFIG_IA64) |
| 123 | # define TIMER_FREQ ((unsigned long long)local_cpu_data->itc_freq) |
| 124 | #else |
| 125 | # define TIMER_FREQ (HZ*loops_per_jiffy) |
| 126 | #endif |
| 127 | |
| 128 | #ifdef HAVE_MONOTONIC |
| 129 | extern unsigned long long monotonic_clock(void); |
| 130 | #else |
| 131 | static inline unsigned long long monotonic_clock(void) |
| 132 | { |
| 133 | return get_cycles(); |
| 134 | } |
| 135 | #endif /* HAVE_MONOTONIC */ |
| 136 | |
| 137 | |
| 138 | /* Last time scheduled */ |
| 139 | static unsigned long long hangcheck_tsc, hangcheck_tsc_margin; |
| 140 | |
| 141 | static void hangcheck_fire(unsigned long); |
| 142 | |
| 143 | static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0); |
| 144 | |
| 145 | |
| 146 | static void hangcheck_fire(unsigned long data) |
| 147 | { |
| 148 | unsigned long long cur_tsc, tsc_diff; |
| 149 | |
| 150 | cur_tsc = monotonic_clock(); |
| 151 | |
| 152 | if (cur_tsc > hangcheck_tsc) |
| 153 | tsc_diff = cur_tsc - hangcheck_tsc; |
| 154 | else |
| 155 | tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */ |
| 156 | |
| 157 | if (tsc_diff > hangcheck_tsc_margin) { |
| 158 | if (hangcheck_dump_tasks) { |
| 159 | printk(KERN_CRIT "Hangcheck: Task state:\n"); |
| 160 | #ifdef CONFIG_MAGIC_SYSRQ |
| 161 | handle_sysrq('t', NULL); |
| 162 | #endif /* CONFIG_MAGIC_SYSRQ */ |
| 163 | } |
| 164 | if (hangcheck_reboot) { |
| 165 | printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n"); |
| 166 | emergency_restart(); |
| 167 | } else { |
| 168 | printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n"); |
| 169 | } |
| 170 | } |
| 171 | mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); |
| 172 | hangcheck_tsc = monotonic_clock(); |
| 173 | } |
| 174 | |
| 175 | |
| 176 | static int __init hangcheck_init(void) |
| 177 | { |
| 178 | printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n", |
| 179 | VERSION_STR, hangcheck_tick, hangcheck_margin); |
| 180 | #if defined (HAVE_MONOTONIC) |
| 181 | printk("Hangcheck: Using monotonic_clock().\n"); |
| 182 | #else |
| 183 | printk("Hangcheck: Using get_cycles().\n"); |
| 184 | #endif /* HAVE_MONOTONIC */ |
| 185 | hangcheck_tsc_margin = |
| 186 | (unsigned long long)(hangcheck_margin + hangcheck_tick); |
| 187 | hangcheck_tsc_margin *= (unsigned long long)TIMER_FREQ; |
| 188 | |
| 189 | hangcheck_tsc = monotonic_clock(); |
| 190 | mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); |
| 191 | |
| 192 | return 0; |
| 193 | } |
| 194 | |
| 195 | |
| 196 | static void __exit hangcheck_exit(void) |
| 197 | { |
| 198 | del_timer_sync(&hangcheck_ticktock); |
| 199 | printk("Hangcheck: Stopped hangcheck timer.\n"); |
| 200 | } |
| 201 | |
| 202 | module_init(hangcheck_init); |
| 203 | module_exit(hangcheck_exit); |