--- /dev/null
+/*
+ * 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>
+ *
+ * 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 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
+ * 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 <linux/delay.h>
+#include <asm/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(unsigned long);
+
+static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0);
+
+static void hangcheck_fire(unsigned long data)
+{
+ 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);
Code Review / kvmfornfv.git / blobdiff