- Add a software watchdog facility.

This commit has two pieces. One half is the watchdog kernel code which lives
primarily in hardclock() in sys/kern/kern_clock.c. The other half is a userland
daemon which, when run, will keep the watchdog from firing while the userland
is intact and functioning.

Approved by:	jeff (mentor)

12 files changed, 560 insertions, 2 deletions

diff --git a/etc/defaults/rc.conf b/etc/defaults/rc.conf
index 1b6f066..d7623ac 100644
--- a/etc/defaults/rc.conf
+++ b/etc/defaults/rc.conf
@@ -430,6 +430,7 @@ jail_list=""		# Space separated list of names of jails
 jail_set_hostname_allow="YES" # Allow root user in a jail to change its hostname
 jail_socket_unixiproute_only="YES" # Route only TCP/IP within a jail
 jail_sysvipc_allow="NO"       # Allow SystemV IPC use from within a jail
+watchdogd_enable="NO"	# Start the software watchdog daemon
 
 ##############################################################
 ### Define source_rc_confs, the mechanism used by /etc/rc.* ##
diff --git a/etc/rc.d/Makefile b/etc/rc.d/Makefile
index 4104707..734a362 100755
--- a/etc/rc.d/Makefile
+++ b/etc/rc.d/Makefile
@@ -17,8 +17,8 @@ FILES=	DAEMON LOGIN NETWORKING SERVERS abi accounting addswap adjkerntz amd \
 	ntpdate othermta pccard pcvt ppp-user pppoed pwcheck quota random \
 	rarpd rcconf.sh root route6d routed rpcbind rtadvd rwho savecore \
 	securelevel sendmail serial sppp sshd swap1 syscons sysctl \
-	syslogd timed ttys usbd vinum virecover ypbind yppasswdd ypserv \
-	ypset ypupdated ypxfrd
+	syslogd timed ttys usbd vinum virecover watchdogd ypbind \
+	yppasswdd ypserv ypset ypupdated ypxfrd
 FILESDIR=	/etc/rc.d
 FILESMODE=	${BINMODE}
 
diff --git a/etc/rc.d/watchdogd b/etc/rc.d/watchdogd
new file mode 100644
index 0000000..e2ee5f7
--- /dev/null
+++ b/etc/rc.d/watchdogd
@@ -0,0 +1,51 @@
+#!/bin/sh
+
+# Copyright (c) 2003  Sean M. Kelly <smkelly@FreeBSD.org>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+#
+
+# PROVIDE: watchdogd
+# REQUIRE: DAEMON
+# KEYWORD: FreeBSD
+
+. /etc/rc.subr
+
+name="watchdogd"
+rcvar="`set_rcvar`"
+command="/usr/sbin/${name}"
+start_precmd="watchdogd_precmd"
+pidfile="/var/run/${name}.pid"
+
+watchdogd_precmd()
+{
+	if ! sysctl debug.watchdog >/dev/null 2>&1; then
+		err 1 "Your kernel doesn't have watchdog support."
+	fi
+	return 0
+}
+
+load_rc_config $name
+run_rc_command "$1"
diff --git a/share/man/man4/Makefile b/share/man/man4/Makefile
index b598875..3198567 100644
--- a/share/man/man4/Makefile
+++ b/share/man/man4/Makefile
@@ -270,6 +270,7 @@ MAN=	aac.4 \
 	vlan.4 \
 	vpo.4 \
 	vr.4 \
+	watchdog.4 \
 	wb.4 \
 	wi.4 \
 	witness.4 \
diff --git a/share/man/man4/watchdog.4 b/share/man/man4/watchdog.4
new file mode 100644
index 0000000..b00ccda
--- /dev/null
+++ b/share/man/man4/watchdog.4
@@ -0,0 +1,77 @@
+
+.\" Copyright (c) 2003  Sean M. Kelly <smkelly@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd June 25, 2003
+.Dt WATCHDOG 4
+.Os
+.Sh NAME
+.Nm watchdog
+.Nd Software watchdog
+.Sh SYNOPSIS
+.Cd options WATCHDOG
+.Sh DESCRIPTION
+.Nm
+is a set of checks and routines which allow the implementation of a software
+watchdog solution.
+.Pp
+The user interface for
+.Nm
+is implemented via a trio of sysctl OIDs.
+When
+.Li debug.watchdog.enabled
+is set to a positive value,
+.Nm
+timeout checks are performed.
+In order to keep the watchdog from triggering,
+.Li debug.watchdog.reset
+must be accessed,
+by reading or writing,
+within every
+.Li debug.watchdog.timeout
+seconds.
+Failure to keep the
+.Nm
+updated will result in the kernel outputting interrupt counts,
+backtraces,
+and then attempting to enter
+.Xr ddb 9 .
+.Sh SEE ALSO
+.Xr sysctl 8 ,
+.Xr watchdogd 8
+.Sh HISTORY
+The
+.Nm
+code first appeared in
+.Fx 5.1 .
+.Sh AUTHORS
+.An -nosplit
+The
+.Nm
+code and manual page were written by
+.An Sean Kelly Aq smkelly@FreeBSD.org .
+Some contributions were made by
+.An Jeff Roberson Aq jeff@FreeBSD.org .
diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index f616f88..c0c8df0 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -2065,6 +2065,13 @@ options 	BOOTP_WIRED_TO=fxp0 # Use interface fxp0 for BOOTP
 options 	HW_WDOG
 
 #
+# Add software watchdog routines.  This will add some sysctl OIDs that
+# can be used in combination with an external daemon to create a
+# software-based watchdog solution.
+#
+options		WATCHDOG
+
+#
 # Disable swapping of upages and stack pages.  This option removes all
 # code which actually performs swapping, so it's not possible to turn
 # it back on at run-time.
diff --git a/sys/conf/options b/sys/conf/options
index cf0f70d..9d3c724 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -442,6 +442,7 @@ MUTEX_PROFILING		opt_global.h
 NPX_DEBUG		opt_debug_npx.h
 NETATALKDEBUG		opt_atalk.h
 SI_DEBUG		opt_debug_si.h
+WATCHDOG		opt_watchdog.h
 
 # Fb options
 FB_DEBUG		opt_fb.h
diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c
index 50a48b1..53729d2 100644
--- a/sys/kern/kern_clock.c
+++ b/sys/kern/kern_clock.c
@@ -42,6 +42,8 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_ntp.h"
+#include "opt_ddb.h"
+#include "opt_watchdog.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -71,6 +73,10 @@ __FBSDID("$FreeBSD$");
 #include <sys/gmon.h>
 #endif
 
+#ifdef DDB
+#include <ddb/ddb.h>
+#endif
+
 #ifdef DEVICE_POLLING
 extern void hardclock_device_poll(void);
 #endif /* DEVICE_POLLING */
@@ -84,6 +90,22 @@ long cp_time[CPUSTATES];
 SYSCTL_OPAQUE(_kern, OID_AUTO, cp_time, CTLFLAG_RD, &cp_time, sizeof(cp_time),
     "LU", "CPU time statistics");
 
+#ifdef WATCHDOG
+static int sysctl_watchdog_reset(SYSCTL_HANDLER_ARGS);
+static void watchdog_fire(void);
+
+static int watchdog_enabled;
+static unsigned int watchdog_ticks;
+static int watchdog_timeout = 20;
+
+SYSCTL_NODE(_debug, OID_AUTO, watchdog, CTLFLAG_RW, 0, "System watchdog");
+SYSCTL_INT(_debug_watchdog, OID_AUTO, enabled, CTLFLAG_RW, &watchdog_enabled,
+	0, "Enable the watchdog");
+SYSCTL_INT(_debug_watchdog, OID_AUTO, timeout, CTLFLAG_RW, &watchdog_timeout,
+	0, "Timeout for watchdog checkins");
+
+#endif /* WATCHDOG */
+
 /*
  * Clock handling routines.
  *
@@ -228,6 +250,12 @@ hardclock(frame)
 	 */
 	if (need_softclock)
 		swi_sched(softclock_ih, 0);
+
+#ifdef WATCHDOG
+	if (watchdog_enabled > 0 &&
+	    (int)(ticks - watchdog_ticks) >= (hz * watchdog_timeout))
+		watchdog_fire();
+#endif /* WATCHDOG */
 }
 
 /*
@@ -481,3 +509,57 @@ sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
 SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate, CTLTYPE_STRUCT|CTLFLAG_RD,
 	0, 0, sysctl_kern_clockrate, "S,clockinfo",
 	"Rate and period of various kernel clocks");
+
+#ifdef WATCHDOG
+/*
+ * Reset the watchdog timer to ticks, thus preventing the watchdog
+ * from firing for another watchdog timeout period.
+ */
+static int
+sysctl_watchdog_reset(SYSCTL_HANDLER_ARGS)
+{
+	int ret;
+
+	ret = 0;
+	watchdog_ticks = ticks;
+	return sysctl_handle_int(oidp, &ret, 0, req);
+}
+
+SYSCTL_PROC(_debug_watchdog, OID_AUTO, reset, CTLFLAG_RW, 0, 0,
+    sysctl_watchdog_reset, "I", "Reset the watchdog");
+
+/*
+ * Handle a watchdog timeout by dumping interrupt information and
+ * then either dropping to DDB or panicing.
+ */
+static void
+watchdog_fire(void)
+{
+	int nintr;
+	u_int64_t inttotal;
+	u_long *curintr;
+	char *curname;
+
+	curintr = intrcnt;
+	curname = intrnames;
+	inttotal = 0;
+	nintr = eintrcnt - intrcnt;
+	
+	printf("interrupt                   total\n");
+	while (--nintr >= 0) {
+		if (*curintr)
+			printf("%-12s %20lu\n", curname, *curintr);
+		curname += strlen(curname) + 1;
+		inttotal += *curintr++;
+	}
+	printf("Total        %20llu\n", inttotal);
+
+#ifdef DDB
+	db_print_backtrace();
+	Debugger("watchdog timeout");
+#else /* !DDB */
+	panic("watchdog timeout");
+#endif /* DDB */
+}
+
+#endif /* WATCHDOG */
diff --git a/usr.sbin/Makefile b/usr.sbin/Makefile
index b394af9..73d3311 100644
--- a/usr.sbin/Makefile
+++ b/usr.sbin/Makefile
@@ -124,6 +124,7 @@ SUBDIR=	IPXrouted \
 	vipw \
 	vnconfig \
 	watch \
+	watchdogd \
 	wicontrol \
 	yp_mkdb \
 	ypbind \
diff --git a/usr.sbin/watchdogd/Makefile b/usr.sbin/watchdogd/Makefile
new file mode 100644
index 0000000..bc8bfd2
--- /dev/null
+++ b/usr.sbin/watchdogd/Makefile
@@ -0,0 +1,8 @@
+# $FreeBSD$
+
+PROG=  watchdogd
+SRCS=  watchdogd.c
+MAN=   watchdogd.8
+WARNS= 6
+
+.include <bsd.prog.mk>
diff --git a/usr.sbin/watchdogd/watchdogd.8 b/usr.sbin/watchdogd/watchdogd.8
new file mode 100644
index 0000000..b8f7ce8
--- /dev/null
+++ b/usr.sbin/watchdogd/watchdogd.8
@@ -0,0 +1,97 @@
+.\" Copyright (c) 2003  Sean M. Kelly <smkelly@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd June 25, 2003
+.Dt WATCHDOGD 8
+.Os
+.Sh NAME
+.Nm watchdogd
+.Nd Software watchdog daemon
+.Sh SYNOPSIS
+.Nm
+.Op Fl d
+.Op Fl I Ar file
+.Sh DESCRIPTION
+The
+.Nm
+utility interfaces with the kernel's software watchdog facility to ensure
+that the system is in a working state.
+If
+.Nm
+is unable to interface with the kernel over a specific timeout,
+the kernel will take actions to assist in debugging or restarting the computer.
+.Pp
+One possible circumstance which will cause a watchdog timeout is an interrupt
+storm.
+If this occurs,
+.Nm
+will no longer execute and thus the kernel's watchdog routines will take
+action after a configurable timeout.
+.Pp
+Upon receiving the
+.Dv SIGTERM
+or
+.Dv SIGINT
+signals,
+.Nm
+will first instruct the kernel to no longer perform watchdog checks and then
+will terminate. 
+.Pp
+The
+.Nm
+utility recognizes the following runtime options:
+.Bl -tag -width ".Fl I Ar file"
+.It Fl I Ar file
+Write the process id of the
+.Nm
+utility in the specified file.
+.It Fl d
+Don't fork.
+When this option is specified,
+.Nm
+will not fork into the background at startup.
+.El
+.Sh FILES
+.Bl -tag -width "/var/run/watchdogd.pid" -compact
+.It Pa /var/run/watchdogd.pid
+.El
+.Sh SEE ALSO
+.Xr watchdog 4 ,
+.Xr sysctl 8
+.Sh AUTHORS
+.An -nosplit
+The
+.Nm
+utility and manual page were written by
+.An Sean Kelly Aq smkelly@FreeBSD.org .
+.Pp
+Some contributions made by
+.An Jeff Roberson Aq jeff@FreeBSD.org .
+.Sh HISTORY
+The
+.Nm
+utility appeared in
+.Fx 5.1 .
diff --git a/usr.sbin/watchdogd/watchdogd.c b/usr.sbin/watchdogd/watchdogd.c
new file mode 100644
index 0000000..3dd2f52
--- /dev/null
+++ b/usr.sbin/watchdogd/watchdogd.c
@@ -0,0 +1,232 @@
+/*
+ * Copyright (c) 2003  Sean M. Kelly <smkelly@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Software watchdog daemon.
+ */
+
+#include <sys/cdefs.h>                                                          
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/sysctl.h>
+#include <sys/time.h>
+#include <sys/rtprio.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <paths.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+#include <signal.h>
+
+static void	parseargs(int, char *[]);
+static void	sighandler(int);
+static void	watchdog_loop(void);
+static int	watchdog_init(void);
+static int	watchdog_onoff(int onoff);
+static int	watchdog_tickle(void);
+static void	usage(void);
+
+int debugging = 0;
+int end_program = 0;
+const char *pidfile = _PATH_VARRUN "watchdogd.pid";
+int reset_mib[3];
+int reset_miblen = 3;
+
+/*
+ * Periodically write to the debug.watchdog.reset sysctl OID
+ * to keep the software watchdog from firing.
+ */
+int
+main(int argc, char *argv[])
+{
+	struct rtprio rtp;
+	FILE *fp;
+
+	if (getuid() != 0)
+		errx(EX_SOFTWARE, "not super user");
+		
+	parseargs(argc, argv);
+
+	rtp.type = RTP_PRIO_REALTIME;
+	rtp.prio = 0;
+	if (rtprio(RTP_SET, 0, &rtp) == -1)
+		err(EX_OSERR, "rtprio");
+
+	if (watchdog_init() == -1)
+		exit(EX_SOFTWARE);
+
+	if (watchdog_onoff(1) == -1)
+		exit(EX_SOFTWARE);
+
+	if (debugging == 0 && daemon(0, 0) == -1) {
+		watchdog_onoff(0);
+		err(EX_OSERR, "daemon");
+	}
+
+	signal(SIGHUP, SIG_IGN);
+	signal(SIGINT, sighandler);
+	signal(SIGTERM, sighandler);
+
+	fp = fopen(pidfile, "w");
+	if (fp != NULL) {
+		fprintf(fp, "%d\n", getpid());
+		fclose(fp);
+	}
+
+	watchdog_loop();
+
+	/* exiting */
+	watchdog_onoff(0);
+	unlink(pidfile);
+	return (EX_OK);
+}
+
+/*
+ * Catch signals and begin shutdown process.
+ */
+static void
+sighandler(int signum)
+{
+
+	if (signum == SIGINT || signum == SIGTERM)
+		end_program = 1;
+}
+
+/*
+ * Locate the OID for the 'debug.watchdog.reset' sysctl setting.
+ * Upon finding it, do an initial reset on the watchdog.
+ */
+static int
+watchdog_init()
+{
+	int error;
+
+	error = sysctlnametomib("debug.watchdog.reset", reset_mib, 
+		&reset_miblen);
+	if (error == -1) {
+		fprintf(stderr, "Could not find reset OID: %s\n",
+			strerror(errno));
+		return (error);
+	}
+	return watchdog_tickle();
+}
+
+/*
+ * Main program loop which is iterated every second.
+ */
+static void
+watchdog_loop(void)
+{
+	struct stat sb;
+	int failed;
+
+	while (end_program == 0) {
+		failed = 0;
+
+		failed = stat("/etc", &sb);
+
+		if (failed == 0)
+			watchdog_tickle();
+		sleep(1);
+	}
+}
+
+/*
+ * Reset the watchdog timer. This function must be called periodically
+ * to keep the watchdog from firing.
+ */
+int
+watchdog_tickle(void)
+{
+
+	return sysctl(reset_mib, reset_miblen, NULL, NULL, NULL, 0);
+}
+
+/*
+ * Toggle the kernel's watchdog. This routine is used to enable and
+ * disable the watchdog.
+ */
+static int
+watchdog_onoff(int onoff)
+{
+	int mib[3]
+	int error
+	int len;
+
+	len = 3;
+
+	error = sysctlnametomib("debug.watchdog.enabled", mib, &len);
+	if (error == 0)
+		error = sysctl(mib, len, NULL, NULL, &onoff, sizeof(onoff));
+
+	if (error == -1) {
+		fprintf(stderr, "Could not %s watchdog: %s\n",
+			(onoff > 0) ? "enable" : "disable",
+			strerror(errno));
+		return (error);
+	}
+	return (0);
+}
+
+/*
+ * Tell user how to use the program.
+ */
+static void
+usage()
+{
+	fprintf(stderr, "usage: watchdogd [-d] [-I file]\n");
+	exit(EX_USAGE);
+}
+
+/*
+ * Handle the few command line arguments supported.
+ */
+static void
+parseargs(int argc, char *argv[])
+{
+	int c;
+
+	while ((c = getopt(argc, argv, "I:d?")) != -1) {
+		switch (c) {
+		case 'I':
+			pidfile = optarg;
+			break;
+		case 'd':
+			debugging = 1;
+			break;
+		case '?':
+		default:
+			usage();
+			/* NOTREACHED */
+		}
+	}
+}