initramfs-framework/udev: call settle before kill

When mount command is executed in rootfs module of initrd, eudev creates
a loop0 device node, applies rules and adds a inotify watch to it. Right
after this step, we execute finish which first tries to kill any running
udevd daemon before doing a switch_root.

In some cases, it is possible that switch_root is executed before
inotify_add_watch was actually processed which would lead to errors like:

| inotify_add_watch(6, /dev/loop0, 10) failed: No such file or directory

Make sure that we process all the events in queue before actually trying
to kill udevd to prevent this race.

Fixes [YOCTO #12861]

(From OE-Core rev: a85c34d263fcf1542bbedcaf1634302466bb20cf)

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

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

@@ -6,6 +6,7 @@ udev_shutdown_hook_handler() {
 	status=$1
 	module=$2
 	if [ "$status" = "pre" ] && [ "$module" = "finish" ]; then
+		udevadm settle
 		killall `basename $_UDEV_DAEMON` 2>/dev/null
 	fi
 }