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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180// 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) { pr_crit("Hangcheck: Task state:\n");#ifdef CONFIG_MAGIC_SYSRQ handle_sysrq('t');#endif /* CONFIG_MAGIC_SYSRQ */ } if (hangcheck_reboot) { pr_crit("Hangcheck: hangcheck is restarting the machine.\n"); emergency_restart(); } else { pr_crit("Hangcheck: hangcheck value past margin!\n"); } }#if 0 /* * Enable to investigate delays in detail */ pr_debug("Hangcheck: called %lld ns since last time (%lld 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){ pr_debug("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){ timer_delete_sync(&hangcheck_ticktock); pr_debug("Hangcheck: Stopped hangcheck timer.\n");}
module_init(hangcheck_init);module_exit(hangcheck_exit);