net: add a core netdev->rx_dropped counter

In various situations, a device provides a packet to our stack and we
drop it before it enters protocol stack :
- softnet backlog full (accounted in /proc/net/softnet_stat)
- bad vlan tag (not accounted)
- unknown/unregistered protocol (not accounted)

We can handle a per-device counter of such dropped frames at core level,
and automatically adds it to the device provided stats (rx_dropped), so
that standard tools can be used (ifconfig, ip link, cat /proc/net/dev)

This is a generalization of commit 8990f468a (net: rx_dropped
accounting), thus reverting it.

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

1 files changed, 1 insertions, 7 deletions

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 4b0e30b564e5..2d9663a1c54d 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -64,7 +64,6 @@ struct pcpu_lstats {
         u64                     packets;
         u64                     bytes;
         struct u64_stats_sync   syncp;
-        unsigned long           drops;
 };
 
 /*
@@ -90,8 +89,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
                 lb_stats->bytes += len;
                 lb_stats->packets++;
                 u64_stats_update_end(&lb_stats->syncp);
-        } else
-                lb_stats->drops++;
+        }
 
         return NETDEV_TX_OK;
 }
@@ -101,7 +99,6 @@ static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev,
 {
         u64 bytes = 0;
         u64 packets = 0;
-        u64 drops = 0;
         int i;
 
         for_each_possible_cpu(i) {
@@ -115,14 +112,11 @@ static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev,
                         tbytes = lb_stats->bytes;
                         tpackets = lb_stats->packets;
                 } while (u64_stats_fetch_retry(&lb_stats->syncp, start));
-                drops   += lb_stats->drops;
                 bytes   += tbytes;
                 packets += tpackets;
         }
         stats->rx_packets = packets;
         stats->tx_packets = packets;
-        stats->rx_dropped = drops;
-        stats->rx_errors  = drops;
         stats->rx_bytes   = bytes;
         stats->tx_bytes   = bytes;
         return stats;