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SubjectRe: [PATCH (take 2)][2.5] hangcheck-timer
	Updated with suggested fixes.

Joel

diff -uNr linux-2.5.59/drivers/char/Kconfig linux-2.5.59-hangcheck/drivers/char/Kconfig
--- linux-2.5.59/drivers/char/Kconfig Thu Jan 16 18:21:36 2003
+++ linux-2.5.59-hangcheck/drivers/char/Kconfig Mon Jan 20 13:35:27 2003
@@ -992,5 +992,8 @@
Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O.
See the raw(8) manpage for more details.

+config HANGCHECK_TIMER
+ tristate "Hangcheck timer"
+
endmenu

diff -uNr linux-2.5.59/drivers/char/Makefile linux-2.5.59-hangcheck/drivers/char/Makefile
--- linux-2.5.59/drivers/char/Makefile Thu Jan 16 18:22:44 2003
+++ linux-2.5.59-hangcheck/drivers/char/Makefile Mon Jan 20 13:35:02 2003
@@ -84,6 +84,7 @@
obj-$(CONFIG_PCMCIA) += pcmcia/
obj-$(CONFIG_IPMI_HANDLER) += ipmi/

+obj-$(CONFIG_HANGCHECK_TIMER) += hangcheck-timer.o

# Files generated that shall be removed upon make clean
clean-files := consolemap_deftbl.c defkeymap.c qtronixmap.c
diff -uNr linux-2.5.59/drivers/char/hangcheck-timer.c linux-2.5.59-hangcheck/drivers/char/hangcheck-timer.c
--- linux-2.5.59/drivers/char/hangcheck-timer.c Wed Dec 31 16:00:00 1969
+++ linux-2.5.59-hangcheck/drivers/char/hangcheck-timer.c Tue Jan 21 10:36:01 2003
@@ -0,0 +1,127 @@
+/*
+ * 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 recieved 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/smp_lock.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_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 = {
+ function: hangcheck_fire,
+};
+
+
+static void hangcheck_fire(unsigned long data)
+{
+ unsigned long long cur_tsc, tsc_diff;
+
+ cur_tsc = get_cycles();
+
+ 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 = get_cycles();
+} /* hangcheck_fire() */
+
+
+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) * (unsigned long long)HZ * (unsigned long long)current_cpu_data.loops_per_jiffy;
+
+ hangcheck_tsc = get_cycles();
+ mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
+
+ return 0;
+} /* hangcheck_init() */
+
+
+static void __exit hangcheck_exit(void)
+{
+ del_timer_sync(&hangcheck_ticktock);
+} /* hangcheck_exit() */
+
+module_init(hangcheck_init);
+module_exit(hangcheck_exit);
--

"Hell is oneself, hell is alone, the other figures in it, merely projections."
- T. S. Eliot

Joel Becker
Senior Member of Technical Staff
Oracle Corporation
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127
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