Merge release-20201109.0-112-gf90ab60a8 (automated)

pkg/tcpip/stack/neighbor_cache.go

@@ -24,9 +24,16 @@ import (
 
 const neighborCacheSize = 512 // max entries per interface
 
+// NeighborStats holds metrics for the neighbor table.
+type NeighborStats struct {
+	// FailedEntryLookups counts the number of lookups performed on an entry in
+	// Failed state.
+	FailedEntryLookups *tcpip.StatCounter
+}
+
 // neighborCache maps IP addresses to link addresses. It uses the Least
 // Recently Used (LRU) eviction strategy to implement a bounded cache for
-// dynmically acquired entries. It contains the state machine and configuration
+// dynamically acquired entries. It contains the state machine and configuration
 // for running Neighbor Unreachability Detection (NUD).
 //
 // There are two types of entries in the neighbor cache:

pkg/tcpip/stack/neighbor_entry.go

@@ -347,9 +347,10 @@ func (e *neighborEntry) handlePacketQueuedLocked(localAddr tcpip.Address) {
 		e.setStateLocked(Delay)
 		e.dispatchChangeEventLocked()
 
-	case Incomplete, Reachable, Delay, Probe, Static, Failed:
+	case Incomplete, Reachable, Delay, Probe, Static:
 		// Do nothing
-
+	case Failed:
+		e.nic.stats.Neighbor.FailedEntryLookups.Increment()
 	default:
 		panic(fmt.Sprintf("Invalid cache entry state: %s", e.neigh.State))
 	}

pkg/tcpip/stack/nic.go

@@ -60,12 +60,14 @@ type NIC struct {
 	}
 }
 
-// NICStats includes transmitted and received stats.
+// NICStats hold statistics for a NIC.
 type NICStats struct {
 	Tx DirectionStats
 	Rx DirectionStats
 
 	DisabledRx DirectionStats
+
+	Neighbor NeighborStats
 }
 
 func makeNICStats() NICStats {