[PATCH net-next] gre: Count GRE packet drops

[Gal Pressman <gal@nvidia.com>]

GRE is silently dropping packets without updating statistics.

In case of drop, increment rx_dropped counter to provide visibility into
packet loss. For the case where no GRE protocol handler is registered,
use rx_nohandler.

Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
---
 net/ipv4/gre_demux.c | 8 ++++++--
 net/ipv4/ip_gre.c    | 1 +
 net/ipv6/ip6_gre.c   | 1 +
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index dafd68f3436a..96fd7dc6d82d 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -159,14 +159,18 @@ static int gre_rcv(struct sk_buff *skb)
 	rcu_read_lock();
 	proto = rcu_dereference(gre_proto[ver]);
 	if (!proto || !proto->handler)
-		goto drop_unlock;
+		goto drop_nohandler;
 	ret = proto->handler(skb);
 	rcu_read_unlock();
 	return ret;
 
-drop_unlock:
+drop_nohandler:
 	rcu_read_unlock();
+	dev_core_stats_rx_nohandler_inc(skb->dev);
+	kfree_skb(skb);
+	return NET_RX_DROP;
 drop:
+	dev_core_stats_rx_dropped_inc(skb->dev);
 	kfree_skb(skb);
 	return NET_RX_DROP;
 }
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 35f0baa99d40..169e2921a851 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -468,6 +468,7 @@ static int gre_rcv(struct sk_buff *skb)
 out:
 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 drop:
+	dev_core_stats_rx_dropped_inc(skb->dev);
 	kfree_skb(skb);
 	return 0;
 }
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index dafcc0dcd77a..63fc8556b475 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -593,6 +593,7 @@ static int gre_rcv(struct sk_buff *skb)
 out:
 	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 drop:
+	dev_core_stats_rx_dropped_inc(skb->dev);
 	kfree_skb(skb);
 	return 0;
 }
-- 
2.52.0