tcp: Increment LISTENOVERFLOW and LISTENDROPS in tcp_v4_conn_request()

We drop a connection request if the accept backlog is full and there are
sufficient packets in the syn queue to warrant starting drops. Increment the
appropriate counters so this isn't silent, for accurate stats and help in
debugging.

This patch assumes LINUX_MIB_LISTENDROPS is a superset of/includes the
counter LINUX_MIB_LISTENOVERFLOWS.

Signed-off-by: Nivedita Singhvi <niv@us.ibm.com>
Acked-by: Vijay Subramanian <subramanian.vijay@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 70b09ef2463b3678c5da4a1d5fc0edb4656e4940..629937d514ebad38b7106dfbcf917434795ea830 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1500,8 +1500,11 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
         * clogging syn queue with openreqs with exponentially increasing
         * timeout.
         */
-       if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
+       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;
+       }
 
        req = inet_reqsk_alloc(&tcp_request_sock_ops);
        if (!req)