batman-adv: Ignore neighbor throughput metrics in error case

If a temporary error happened in the evaluation of the neighbor throughput
information, then the invalid throughput result should not be stored in the
throughtput EWMA.

Cc: stable@vger.kernel.org
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/bat_v_elp.c

@@ -59,11 +59,13 @@ static void batadv_v_elp_start_timer(struct batadv_hard_iface *hard_iface)
 /**
  * batadv_v_elp_get_throughput() - get the throughput towards a neighbour
  * @neigh: the neighbour for which the throughput has to be obtained
+ * @pthroughput: calculated throughput towards the given neighbour in multiples
+ *  of 100kpbs (a value of '1' equals 0.1Mbps, '10' equals 1Mbps, etc).
  *
- * Return: The throughput towards the given neighbour in multiples of 100kpbs
+ * Return: true when value behind @pthroughput was set
- *         (a value of '1' equals 0.1Mbps, '10' equals 1Mbps, etc).
  */
-static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
+static bool batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh,
+					u32 *pthroughput)
 {
 	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
 	struct net_device *soft_iface = hard_iface->soft_iface;
@@ -77,14 +79,16 @@ static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
 	 * batman-adv interface
 	 */
 	if (!soft_iface)
-		return BATADV_THROUGHPUT_DEFAULT_VALUE;
+		return false;
 
 	/* if the user specified a customised value for this interface, then
 	 * return it directly
 	 */
 	throughput =  atomic_read(&hard_iface->bat_v.throughput_override);
-	if (throughput != 0)
+	if (throughput != 0) {
-		return throughput;
+		*pthroughput = throughput;
+		return true;
+	}
 
 	/* if this is a wireless device, then ask its throughput through
 	 * cfg80211 API
@@ -111,19 +115,24 @@ static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
 			 * possible to delete this neighbor. For now set
 			 * the throughput metric to 0.
 			 */
-			return 0;
+			*pthroughput = 0;
+			return true;
 		}
 		if (ret)
 			goto default_throughput;
 
-		if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT))
+		if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT)) {
-			return sinfo.expected_throughput / 100;
+			*pthroughput = sinfo.expected_throughput / 100;
+			return true;
+		}
 
 		/* try to estimate the expected throughput based on reported tx
 		 * rates
 		 */
-		if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE))
+		if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE)) {
-			return cfg80211_calculate_bitrate(&sinfo.txrate) / 3;
+			*pthroughput = cfg80211_calculate_bitrate(&sinfo.txrate) / 3;
+			return true;
+		}
 
 		goto default_throughput;
 	}
@@ -142,8 +151,10 @@ static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
 			hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;
 
 		throughput = link_settings.base.speed;
-		if (throughput && throughput != SPEED_UNKNOWN)
+		if (throughput && throughput != SPEED_UNKNOWN) {
-			return throughput * 10;
+			*pthroughput = throughput * 10;
+			return true;
+		}
 	}
 
 default_throughput:
@@ -157,7 +168,8 @@ default_throughput:
 	}
 
 	/* if none of the above cases apply, return the base_throughput */
-	return BATADV_THROUGHPUT_DEFAULT_VALUE;
+	*pthroughput = BATADV_THROUGHPUT_DEFAULT_VALUE;
+	return true;
 }
 
 /**
@@ -169,15 +181,21 @@ void batadv_v_elp_throughput_metric_update(struct work_struct *work)
 {
 	struct batadv_hardif_neigh_node_bat_v *neigh_bat_v;
 	struct batadv_hardif_neigh_node *neigh;
+	u32 throughput;
+	bool valid;
 
 	neigh_bat_v = container_of(work, struct batadv_hardif_neigh_node_bat_v,
 				   metric_work);
 	neigh = container_of(neigh_bat_v, struct batadv_hardif_neigh_node,
 			     bat_v);
 
-	ewma_throughput_add(&neigh->bat_v.throughput,
+	valid = batadv_v_elp_get_throughput(neigh, &throughput);
-			    batadv_v_elp_get_throughput(neigh));
+	if (!valid)
+		goto put_neigh;
 
+	ewma_throughput_add(&neigh->bat_v.throughput, throughput);
+
+put_neigh:
 	/* decrement refcounter to balance increment performed before scheduling
 	 * this task
 	 */