mac80211: Rewrote code for checking if destinations are proxied.

Rewrote code for checking if the destination is proxied by a mesh portal, to facilitate better
understanding of the functionality.
Signed-off-by: Joel A Fernandes <agnel.joel@gmail.com>
Acked-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/tx.c

@@ -1815,19 +1815,19 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
 			mppath = mpp_path_lookup(skb->data, sdata);
 
 		/*
-		 * Do not use address extension, if it is a packet from
-		 * the same interface and the destination is not being
-		 * proxied by any other mest point.
+		 * Use address extension if it is a packet from
+		 * another interface or if we know the destination
+		 * is being proxied by a portal (i.e. portal address
+		 * differs from proxied address)
 		 */
 		if (compare_ether_addr(sdata->vif.addr,
 				       skb->data + ETH_ALEN) == 0 &&
-		    (!mppath || !compare_ether_addr(mppath->mpp, skb->data))) {
+		    !(mppath && compare_ether_addr(mppath->mpp, skb->data))) {
 			hdrlen = ieee80211_fill_mesh_addresses(&hdr, &fc,
 					skb->data, skb->data + ETH_ALEN);
 			meshhdrlen = ieee80211_new_mesh_header(&mesh_hdr,
 					sdata, NULL, NULL);
 		} else {
-			/* packet from other interface */
 			int is_mesh_mcast = 1;
 			const u8 *mesh_da;