mac802154: don't deliver packets to devices that are down

Only one WPAN devices can be active at any given time, so only deliver
packets to that one interface that is actually up. Multiple monitors may
be up at any given time, but we don't have to deliver to monitors that
are down either.

Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac802154/wpan.c b/net/mac802154/wpan.c
index c8cfd54..3c3069f 100644
--- a/net/mac802154/wpan.c
+++ b/net/mac802154/wpan.c
@@ -567,7 +567,6 @@
 void mac802154_wpans_rx(struct mac802154_priv *priv, struct sk_buff *skb)
 {
 	int ret;
-	struct sk_buff *sskb;
 	struct mac802154_sub_if_data *sdata;
 	struct ieee802154_hdr hdr;
 
@@ -579,12 +578,16 @@
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(sdata, &priv->slaves, list) {
-		if (sdata->type != IEEE802154_DEV_WPAN)
+		if (sdata->type != IEEE802154_DEV_WPAN ||
+		    !netif_running(sdata->dev))
 			continue;
 
-		sskb = skb_clone(skb, GFP_ATOMIC);
-		if (sskb)
-			mac802154_subif_frame(sdata, sskb, &hdr);
+		mac802154_subif_frame(sdata, skb, &hdr);
+		skb = NULL;
+		break;
 	}
 	rcu_read_unlock();
+
+	if (skb)
+		kfree_skb(skb);
 }