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 000000000000..83d6b37b36cd
--- /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);