diff options
Diffstat (limited to 'drivers/char/hangcheck-timer.c')
| -rw-r--r-- | drivers/char/hangcheck-timer.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/drivers/char/hangcheck-timer.c b/drivers/char/hangcheck-timer.c new file mode 100644 index 000000000..4181bcc1c --- /dev/null +++ b/drivers/char/hangcheck-timer.c @@ -0,0 +1,175 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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> + */ + +/* + * 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 */ + +/* 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 */ + +#define TIMER_FREQ 1000000000ULL + +/* Last time scheduled */ +static unsigned long long hangcheck_tsc, hangcheck_tsc_margin; + +static void hangcheck_fire(struct timer_list *); + +static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire); + +static void hangcheck_fire(struct timer_list *unused) +{ + unsigned long long cur_tsc, tsc_diff; + + cur_tsc = ktime_get_ns(); + + 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'); +#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"); + } + } +#if 0 + /* + * Enable to investigate delays in detail + */ + printk("Hangcheck: called %Ld ns since last time (%Ld ns overshoot)\n", + tsc_diff, tsc_diff - hangcheck_tick*TIMER_FREQ); +#endif + mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); + hangcheck_tsc = ktime_get_ns(); +} + + +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); + hangcheck_tsc_margin = + (unsigned long long)hangcheck_margin + hangcheck_tick; + hangcheck_tsc_margin *= TIMER_FREQ; + + hangcheck_tsc = ktime_get_ns(); + 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); |