diff options
Diffstat (limited to 'drivers/char/hangcheck-timer.c')
| -rw-r--r-- | drivers/char/hangcheck-timer.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/drivers/char/hangcheck-timer.c b/drivers/char/hangcheck-timer.c new file mode 100644 index 00000000000..83d6b37b36c --- /dev/null +++ b/drivers/char/hangcheck-timer.c @@ -0,0 +1,129 @@ +/* + * hangcheck-timer.c + * + * Driver for a little io fencing timer. + * + * Copyright (C) 2002 Oracle Corporation. 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/init.h> +#include <asm/uaccess.h> + + +#define VERSION_STR "0.5.0" + +#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 */ + +/* Driver options */ +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_AUTHOR("Joel Becker"); +MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin."); +MODULE_LICENSE("GPL"); + + +/* Last time scheduled */ +static unsigned long long hangcheck_tsc, hangcheck_tsc_margin; + +static void hangcheck_fire(unsigned long); + +static struct timer_list hangcheck_ticktock = + TIMER_INITIALIZER(hangcheck_fire, 0, 0); + +extern unsigned long long monotonic_clock(void); + +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_reboot) { + printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n"); + machine_restart(NULL); + } 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); + + hangcheck_tsc_margin = hangcheck_margin + hangcheck_tick; + hangcheck_tsc_margin *= 1000000000; + + + 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); +} + +module_init(hangcheck_init); +module_exit(hangcheck_exit); |