net: Add MIB counters for checksum errors

Add MIB counters for checksum errors in IP layer,
and TCP/UDP/ICMP layers, to help diagnose problems.

$ nstat -a | grep  Csum
IcmpInCsumErrors                72                 0.0
TcpInCsumErrors                 382                0.0
UdpInCsumErrors                 463221             0.0
Icmp6InCsumErrors               75                 0.0
Udp6InCsumErrors                173442             0.0
IpExtInCsumErrors               10884              0.0

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 9 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index e51bd1a58264..71167069b394 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1405,6 +1405,7 @@ discard:
         kfree_skb(skb);
         return 0;
 csum_err:
+        TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
         TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
         goto discard;
 
@@ -1466,7 +1467,7 @@ static int tcp_v6_rcv(struct sk_buff *skb)
                 goto discard_it;
 
         if (!skb_csum_unnecessary(skb) && tcp_v6_checksum_init(skb))
-                goto bad_packet;
+                goto csum_error;
 
         th = tcp_hdr(skb);
         hdr = ipv6_hdr(skb);
@@ -1530,6 +1531,8 @@ no_tcp_socket:
                 goto discard_it;
 
         if (skb->len < (th->doff<<2) || tcp_checksum_complete(skb)) {
+csum_error:
+                TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
 bad_packet:
                 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
         } else {
@@ -1537,11 +1540,6 @@ bad_packet:
         }
 
 discard_it:
-
-        /*
-         *      Discard frame
-         */
-
         kfree_skb(skb);
         return 0;
 
@@ -1555,10 +1553,13 @@ do_time_wait:
                 goto discard_it;
         }
 
-        if (skb->len < (th->doff<<2) || tcp_checksum_complete(skb)) {
-                TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
+        if (skb->len < (th->doff<<2)) {
                 inet_twsk_put(inet_twsk(sk));
-                goto discard_it;
+                goto bad_packet;
+        }
+        if (tcp_checksum_complete(skb)) {
+                inet_twsk_put(inet_twsk(sk));
+                goto csum_error;
         }
 
         switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {