[PATCH net] tcp: Update MIB counters for drops

[Vijay Subramanian <subramanian.vijay@gmail.com>]

This patch updates LINUX_MIB_LISTENDROPS and LINUX_MIB_LISTENOVERFLOWS in
tcp_v4_conn_request() and tcp_v4_err(). tcp_v4_conn_request() in particular can
drop SYNs for various reasons which are not currently tracked.

Signed-off-by: Vijay Subramanian <subramanian.vijay@gmail.com>
---
Ignored "line over 80 chars" warning for readability.

 net/ipv4/tcp_ipv4.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 629937d..029ac1f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -496,6 +496,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 		 * errors returned from accept().
 		 */
 		inet_csk_reqsk_queue_drop(sk, req, prev);
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
 		goto out;
 
 	case TCP_SYN_SENT:
@@ -1491,8 +1492,10 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	 */
 	if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
 		want_cookie = tcp_syn_flood_action(sk, skb, "TCP");
-		if (!want_cookie)
+		if (!want_cookie) {
+			NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
 			goto drop;
+		}
 	}
 
 	/* Accept backlog is full. If we have already queued enough
@@ -1502,7 +1505,6 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	 */
 	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
 		goto drop;
 	}
 
@@ -1669,6 +1671,7 @@ drop_and_release:
 drop_and_free:
 	reqsk_free(req);
 drop:
+	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
 	return 0;
 }
 EXPORT_SYMBOL(tcp_v4_conn_request);
-- 
1.7.0.4