aredn/files/usr/local/bin/upgrade_kill_prep

#!/bin/sh

# Code in this script is derived from OpenWRT
# GPLv2 License

kill_remaining() { # [ <signal> ]
	local sig="${1:-TERM}"
	printf "Sending %s to remaining processes ... " "$sig"

	local my_pid=$$
	local my_ppid
	my_ppid=$(cut -d' ' -f4  /proc/$my_pid/stat)
	local my_ppisupgraded=
	grep -q upgraded "/proc/$my_ppid/cmdline" >/dev/null && {
		local my_ppisupgraded=1
	}

	local stat
	for stat in /proc/[0-9]*/stat; do
		[ -f "$stat" ] || continue

		local pid name _ ppid rest
		read pid name _ ppid rest < "$stat"
		name="${name#(}"; name="${name%)}"

		local cmdline
		read cmdline < "/proc/$pid/cmdline"

		# Skip kernel threads
		[ -n "$cmdline" ] || continue

		if [ $$ -eq 1 ] || [ "$my_ppid" -eq 1 ] && [ -n "$my_ppisupgraded" ]; then
			# Running as init process, kill everything except me
			if [ "$pid" -ne $$ ] && [ "$pid" -ne "$my_ppid" ]; then
				printf "%s " "$name"
				kill "-$sig" "$pid" 2>/dev/null
			fi
		else 
			case "$name" in
				# Skip essential services
				*procd*|*ash*|*init*|*ssh*|*dropbear*|*login*|*uhttpd*|*admin*|*sysupgrade*|*upgrade_kill_prep*|*olsr*|*ubusd*) : ;;

				# Killable process
				*)
					if [ "$pid" -ne $$ ] && [ "$ppid" -ne $$ ]; then
						printf "%s " "$name"
						kill "-$sig" "$pid" 2>/dev/null
					fi
				;;
			esac
		fi
	done
	echo ""
}

/etc/init.d/cron stop
kill_remaining TERM
sleep 3
kill_remaining KILL
sleep 1