check exit code

package/base-files/src/sbin/adkupdate

@@ -30,8 +30,10 @@ prepare() {
 	cd /
 	if [ -x /sbin/cfgfs ];then
 		umount -f /etc
+		check_exit
 	fi
 	mount -o remount,rw /
+	check_exit
 	if [ "$system" == "RB532" ];then
 		mount -t yaffs2 /dev/mtdblock0 /boot
 	elif [ "$system" == "AR7130" ];then