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, 3 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 92d81edd5808..6abcef67b178 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -884,6 +884,9 @@ struct net_device {
         int                     iflink;
 
         struct net_device_stats stats;
+        atomic_long_t           rx_dropped; /* dropped packets by core network
+                                             * Do not use this in drivers.
+                                             */
 
 #ifdef CONFIG_WIRELESS_EXT
         /* List of functions to handle Wireless Extensions (instead of ioctl).