initramds-framework: add shutdown hook for udev

In cases where other initramfs modules need to rely on
udev running (ie in my case I have to load firmware on
a device that is slow to start) there needs to be a way
to keep it running during the lifecycle of the initramfs
but still be shut down before swith_root is called.  I
added a  module_pre_hook that will shut down udev before
the finish module is called.

(From OE-Core rev: ce690659ef797bd26dc2be59167aa01744841510)

Signed-off-by: Ian Reinhart Geiser <igeiser@devonit.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/initrdscripts/initramfs-framework/udev

@@ -2,6 +2,14 @@
 # Copyright (C) 2011, 2012 O.S. Systems Software LTDA.
 # Licensed on MIT
 
+udev_shutdown_hook_handler() {
+	status=$1
+	module=$2
+	if [ "$status" = "pre" ] && [ "$module" = "finish" ]; then
+		killall `basename $_UDEV_DAEMON` 2>/dev/null
+	fi
+}
+
 udev_daemon() {
 	OPTIONS="/sbin/udevd /lib/udev/udevd /lib/systemd/systemd-udevd"
 
@@ -27,11 +35,11 @@ udev_enabled() {
 }
 
 udev_run() {
+	add_module_pre_hook "udev_shutdown_hook_handler"
+
 	mkdir -p /run
 
 	$_UDEV_DAEMON --daemon
 	udevadm trigger --action=add
 	udevadm settle
-
-	killall `basename $_UDEV_DAEMON` 2>/dev/null
 }