add ability to set watchdog timeout for a shutdown

This change allows to specify a watchdog(9) timeout for a system
shutdown.  The timeout is activated when the watchdogd daemon is
stopped.  The idea is to a prevent any indefinite hang during late
stages of the shutdown.  The feature is implemented in rc.d/watchdogd,
it builds upon watchdogd -x option.

Note that the shutdown timeout is not actiavted when the watchdogd
service is individually stopped by an operator.  It is also not
activated for the 'shutdown' to the single-user mode.  In those cases it
is assumed that the operator knows what they are doing and they have
means to recover the system should it hang.

Significant subchanges and implementation details:
- the argument to rc.shutdown, completely unused before, is assigned to
  rc_shutdown variable that can be inspected by rc scripts
- init(8) passes "single" or "reboot" as the argument, this is not
  changed
- the argument is not mandatory and if it is not set then rc_shutdown is
  set to "unspecified"
- however, the default jail management scripts and jail configuration
  examples have been updated to pass "jail" to rc.shutdown, just in case
- the new timeout can be set via watchdogd_shutdown_timeout rc option
- for consistency, the regular timeout can now be set via
  watchdogd_timeout rc option
- watchdogd_shutdown_timeout and watchdogd_timeout override timeout
  specifications in watchdogd_flags
- existing configurations, where the new rc options are not set, should
  keep working as before

I am not particularly wed to any of the implementation specifics.
I am open to changing or removing any of them as long as the provided
functionality is the same (or very close) to the proposed one.
For example, I think it can be implemented without using watchdogd -x,
by means of watchdog(1) alone.  In that case there would be a small
window between stopping watchdogd and running watchdog, but I think that
that is acceptable.

Reviewed by:	bcr (man page changes)
MFC after:	5 weeks
Relnotes:	yes
Differential Revision: https://reviews.freebsd.org/D21221

libexec/rc/rc.conf

@@ -679,6 +679,10 @@ harvest_mask="511"	# Entropy device harvests all but the very invasive sources.
 dmesg_enable="YES"	# Save dmesg(8) to /var/run/dmesg.boot
 watchdogd_enable="NO"	# Start the software watchdog daemon
 watchdogd_flags=""	# Flags to watchdogd (if enabled)
+watchdogd_timeout=""	# watchdogd timeout, overrides -t in watchdogd_flags
+watchdogd_shutdown_timeout=""	# Timeout to use after watchdogd is stopped.
+				# Has effect only for system shutdown.
+				# Overrides -x in watchdogd_flags.
 devfs_rulesets="/etc/defaults/devfs.rules /etc/devfs.rules" # Files containing
 							    # devfs(8) rules.
 devfs_system_ruleset=""	# The name (NOT number) of a ruleset to apply to /dev

libexec/rc/rc.d/jail

@@ -168,7 +168,7 @@ parse_options()
 		if [ -z "${_exec_start}" ]; then
 			_exec_start="/bin/sh /etc/rc"
 			if [ -z "${_exec_stop}" ]; then
-				_exec_stop="/bin/sh /etc/rc.shutdown"
+				_exec_stop="/bin/sh /etc/rc.shutdown jail"
 			fi
 		fi
 	fi

libexec/rc/rc.d/watchdogd

@@ -38,9 +38,55 @@ desc="Watchdog daemon"
 rcvar="watchdogd_enable"
 command="/usr/sbin/${name}"
 pidfile="/var/run/${name}.pid"
+start_precmd="watchdogd_prestart"
+stop_precmd="watchdogd_prestop"
+stop_postcmd="watchdogd_poststop"
+watchdog_command="/usr/sbin/watchdog"
+
+watchdogd_prestart()
+{
+	if [ -n "${watchdogd_timeout}" ] ; then
+		rc_flags="${rc_flags} -t ${watchdogd_timeout}"
+	fi
+	if [ -n "$watchdogd_shutdown_timeout" ] ; then
+		rc_flags="${rc_flags} -x ${watchdogd_shutdown_timeout}"
+	fi
+	return 0
+}
+
+watchdogd_prestop()
+{
+	sig_stop="${watchdogd_sig_stop:-TERM}"
+}
+
+watchdogd_poststop()
+{
+	if [ ${watchdogd_shutdown_timeout:-0} -gt 0 ] ; then
+		case "${rc_shutdown}" in
+		"reboot")
+			info "watchdog timer is set to" \
+				${watchdogd_shutdown_timeout} "before shutdown"
+			return 0
+			;;
+		"single")
+			info "watchdog timer is disabled before going to" \
+				"single user mode"
+			${watchdog_command} -t 0
+			;;
+		"")
+			info "watchdog timer is disabled after administrative" \
+				"${name} stop"
+			${watchdog_command} -t 0
+			;;
+		*)
+			warn "unknown shutdown mode '${rc_shutdown}'"
+			warn "watchdog timer is set to ${watchdogd_shutdown_timeout}"
+			return 0
+			;;
+		esac
+	fi
+	return 0
+}
 
 load_rc_config $name
-
-sig_stop="${watchdogd_sig_stop:-TERM}"
-
 run_rc_command "$1"

libexec/rc/rc.shutdown

@@ -43,6 +43,8 @@ HOME=/
 PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin
 export HOME PATH
 
+rc_shutdown=${1:-"unspecified"}
+
 . /etc/rc.subr
 
 load_rc_config

sbin/init/init.8

@@ -31,7 +31,7 @@
 .\"     @(#)init.8	8.3 (Berkeley) 4/18/94
 .\" $FreeBSD$
 .\"
-.Dd August 15, 2018
+.Dd August 6, 2019
 .Dt INIT 8
 .Os
 .Sh NAME
@@ -270,6 +270,15 @@ The timeout can be configured via the
 variable
 .Va kern.init_shutdown_timeout .
 .Pp
+.Nm init
+passes
+.Dq Li single
+as the argument to the shutdown script if return to single-user mode
+is requested.
+Otherwise,
+.Dq Li reboot
+argument is used.
+.Pp
 The role of
 .Nm
 is so critical that if it dies, the system will reboot itself

share/examples/jails/jail.xxx.conf

@@ -23,7 +23,7 @@ xxx {
 
 	# Standard recipe
 	exec.start += "/bin/sh /etc/rc";
-	exec.stop = "/bin/sh /etc/rc.shutdown";
+	exec.stop = "/bin/sh /etc/rc.shutdown jail";
 	exec.consolelog = "/var/log/jail_xxx_console.log";
 	mount.devfs;	# mount devfs
 

share/examples/jails/jib

@@ -67,7 +67,7 @@
 # 
 # 	# Standard recipe
 # 	exec.start += "/bin/sh /etc/rc";
-# 	exec.stop = "/bin/sh /etc/rc.shutdown";
+# 	exec.stop = "/bin/sh /etc/rc.shutdown jail";
 # 	exec.consolelog = "/var/log/jail_xxx_console.log";
 # 	mount.devfs;
 #

share/examples/jails/jng

@@ -67,7 +67,7 @@
 # 
 # 	# Standard recipe
 # 	exec.start += "/bin/sh /etc/rc";
-# 	exec.stop = "/bin/sh /etc/rc.shutdown";
+# 	exec.stop = "/bin/sh /etc/rc.shutdown jail";
 # 	exec.consolelog = "/var/log/jail_xxx_console.log";
 # 	mount.devfs;
 #

share/man/man5/rc.conf.5

@@ -3738,6 +3738,41 @@ is set to
 these are the flags passed to the
 .Xr watchdogd 8
 daemon.
+.It Va watchdogd_timeout
+.Pq Vt int
+If
+.Va watchdogd_enable
+is set to
+.Dq Li YES ,
+this is a timeout that will be used by the
+.Xr watchdogd 8
+daemon.
+If this option is set, it overrides
+.Fl t
+in
+.Va watchdogd_flags .
+.It Va watchdogd_shutdown_timeout
+.Pq Vt int
+If
+.Va watchdogd_enable
+is set to
+.Dq Li YES ,
+this is a timeout that will be set by the
+.Xr watchdogd 8
+daemon when it exits during the system shutdown.
+This timeout will not be set when returning to the single-user mode
+or when the watchdogd service is stopped individually using the
+.Xr service 8
+command or the rc.d script.
+Note that the timeout will be applied if
+.Xr watchdogd 8
+is stopped outside of
+.Xr rc 8
+framework.
+If this option is set, it overrides
+.Fl x
+in
+.Va watchdogd_flags .
 .It Va devfs_rulesets
 .Pq Vt str
 List of files containing sets of rules for

share/man/man8/rc.8

@@ -189,6 +189,14 @@ also exists (because it was created by a script), then delete it and reboot.
 .Ss Operation of Nm rc.shutdown
 .Bl -enum
 .It
+Set
+.Va rc_shutdown
+to the value of the first argument passed to
+.Nm rc.shutdown
+or to
+.Dq Li unspecified
+if no argument was passed.
+.It
 Source
 .Pa /etc/rc.subr
 to load various

usr.sbin/jail/jail.8

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 18, 2019
+.Dd August 6, 2019
 .Dt JAIL 8
 .Os
 .Sh NAME
@@ -681,7 +681,7 @@ A value of
 .Dq inherit
 will keep the same environment, and
 .Dq new
-will give the jail it's own environment (still originally inherited when
+will give the jail its own environment (still originally inherited when
 the jail is created).
 .It Va linux.osname , linux.osrelease , linux.oss_version
 The Linux OS name, OS release, and OSS version associated with this jail.
@@ -754,7 +754,7 @@ and after any
 .Va exec.prestop
 commands have completed.
 A typical command to run is
-.Dq sh /etc/rc.shutdown .
+.Dq sh /etc/rc.shutdown jail .
 .It Va exec.poststop
 Command(s) to run in the system environment after a jail is removed.
 .It Va exec.clean
@@ -1103,7 +1103,7 @@ testjail {
 	ip4.addr = 192.0.2.100;
 	interface = em0;
 	exec.start = "/bin/sh /etc/rc";
-	exec.stop = "/bin/sh /etc/rc.shutdown";
+	exec.stop = "/bin/sh /etc/rc.shutdown jail";
 }
 .Ed
 .Pp

usr.sbin/jail/jail.conf.5

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 13, 2014
+.Dd August 6, 2019
 .Dt JAIL.CONF 5
 .Os
 .Sh NAME
@@ -182,7 +182,7 @@ in the middle of a string or a token.
 # Typical static defaults:
 # Use the rc scripts to start and stop jails.  Mount jail's /dev.
 exec.start = "/bin/sh /etc/rc";
-exec.stop = "/bin/sh /etc/rc.shutdown";
+exec.stop = "/bin/sh /etc/rc.shutdown jail";
 exec.clean;
 mount.devfs;