mac80211: fix the update of path metric for RANN frame

The previous path metric update from RANN frame has not considered
the own link metric toward the transmitting mesh STA. Fix this.

Reported-by: Michael65535
Signed-off-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mesh_hwmp.c

@@ -797,7 +797,7 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 	struct mesh_path *mpath;
 	u8 ttl, flags, hopcount;
 	const u8 *orig_addr;
-	u32 orig_sn, metric, metric_txsta, interval;
+	u32 orig_sn, new_metric, orig_metric, last_hop_metric, interval;
 	bool root_is_gate;
 
 	ttl = rann->rann_ttl;
@@ -808,7 +808,7 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 	interval = le32_to_cpu(rann->rann_interval);
 	hopcount = rann->rann_hopcount;
 	hopcount++;
-	metric = le32_to_cpu(rann->rann_metric);
+	orig_metric = le32_to_cpu(rann->rann_metric);
 
 	/*  Ignore our own RANNs */
 	if (ether_addr_equal(orig_addr, sdata->vif.addr))
@@ -825,7 +825,10 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 		return;
 	}
 
-	metric_txsta = airtime_link_metric_get(local, sta);
+	last_hop_metric = airtime_link_metric_get(local, sta);
+	new_metric = orig_metric + last_hop_metric;
+	if (new_metric < orig_metric)
+		new_metric = MAX_METRIC;
 
 	mpath = mesh_path_lookup(sdata, orig_addr);
 	if (!mpath) {
@@ -838,7 +841,7 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 	}
 
 	if (!(SN_LT(mpath->sn, orig_sn)) &&
-	    !(mpath->sn == orig_sn && metric < mpath->rann_metric)) {
+	    !(mpath->sn == orig_sn && new_metric < mpath->rann_metric)) {
 		rcu_read_unlock();
 		return;
 	}
@@ -856,7 +859,7 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 	}
 
 	mpath->sn = orig_sn;
-	mpath->rann_metric = metric + metric_txsta;
+	mpath->rann_metric = new_metric;
 	mpath->is_root = true;
 	/* Recording RANNs sender address to send individually
 	 * addressed PREQs destined for root mesh STA */
@@ -876,7 +879,7 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 		mesh_path_sel_frame_tx(MPATH_RANN, flags, orig_addr,
 				       orig_sn, 0, NULL, 0, broadcast_addr,
 				       hopcount, ttl, interval,
-				       metric + metric_txsta, 0, sdata);
+				       new_metric, 0, sdata);
 	}
 
 	rcu_read_unlock();