nl802154: avoid address change while running lowpan

The generation of autoconfigured IPv6 link-local addresses starts with a
notification on interface up.

To handle autoconfiguration according to RFC 4944 requires pan id and
short address to generate an autoconfigured link-local address. This
patch will avoid changing of these link-layer address configuration
while lowpan interface is up.
Reviewed-by: NStefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: NAlexander Aring <aar@pengutronix.de>
Acked-by: NJukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/ieee802154/nl802154.c

@@ -1074,6 +1074,11 @@ static int nl802154_set_pan_id(struct sk_buff *skb, struct genl_info *info)
 	if (netif_running(dev))
 		return -EBUSY;
 
+	if (wpan_dev->lowpan_dev) {
+		if (netif_running(wpan_dev->lowpan_dev))
+			return -EBUSY;
+	}
+
 	/* don't change address fields on monitor */
 	if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR ||
 	    !info->attrs[NL802154_ATTR_PAN_ID])
@@ -1105,6 +1110,11 @@ static int nl802154_set_short_addr(struct sk_buff *skb, struct genl_info *info)
 	if (netif_running(dev))
 		return -EBUSY;
 
+	if (wpan_dev->lowpan_dev) {
+		if (netif_running(wpan_dev->lowpan_dev))
+			return -EBUSY;
+	}
+
 	/* don't change address fields on monitor */
 	if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR ||
 	    !info->attrs[NL802154_ATTR_SHORT_ADDR])