net: rx_dropped accounting

Under load, netif_rx() can drop incoming packets but administrators dont
have a chance to spot which device needs some tuning (RPS activation for
example)

This patch adds rx_dropped accounting in vlans and tunnels.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 9 insertions, 2 deletions

diff --git a/net/8021q/vlan.h b/net/8021q/vlan.h
index 8d9503ad01da..b26ce343072c 100644
--- a/net/8021q/vlan.h
+++ b/net/8021q/vlan.h
@@ -25,6 +25,7 @@ struct vlan_priority_tci_mapping {
  *      @rx_multicast: number of received multicast packets
  *      @syncp: synchronization point for 64bit counters
  *      @rx_errors: number of errors
+ *      @rx_dropped: number of dropped packets
  */
 struct vlan_rx_stats {
         u64                     rx_packets;
@@ -32,6 +33,7 @@ struct vlan_rx_stats {
         u64                     rx_multicast;
         struct u64_stats_sync   syncp;
         unsigned long           rx_errors;
+        unsigned long           rx_dropped;
 };
 
 /**
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 3bccdd12a264..94a1feddeb49 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -225,7 +225,10 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
                 }
         }
 
-        netif_rx(skb);
+        if (unlikely(netif_rx(skb) == NET_RX_DROP)) {
+                if (rx_stats)
+                        rx_stats->rx_dropped++;
+        }
         rcu_read_unlock();
         return NET_RX_SUCCESS;
 
@@ -843,13 +846,15 @@ static struct rtnl_link_stats64 *vlan_dev_get_stats64(struct net_device *dev, st
                         accum.rx_packets += rxpackets;
                         accum.rx_bytes   += rxbytes;
                         accum.rx_multicast += rxmulticast;
-                        /* rx_errors is an ulong, not protected by syncp */
+                        /* rx_errors, rx_dropped are ulong, not protected by syncp */
                         accum.rx_errors  += p->rx_errors;
+                        accum.rx_dropped += p->rx_dropped;
                 }
                 stats->rx_packets = accum.rx_packets;
                 stats->rx_bytes   = accum.rx_bytes;
                 stats->rx_errors  = accum.rx_errors;
                 stats->multicast  = accum.rx_multicast;
+                stats->rx_dropped = accum.rx_dropped;
         }
         return stats;
 }