[TCP]: SNMPv2 tcpAttemptFails counter error

Refer to RFC2012, tcpAttemptFails is defined as following:
  tcpAttemptFails OBJECT-TYPE
      SYNTAX      Counter32
      MAX-ACCESS  read-only
      STATUS      current
      DESCRIPTION
              "The number of times TCP connections have made a direct
              transition to the CLOSED state from either the SYN-SENT
              state or the SYN-RCVD state, plus the number of times TCP
              connections have made a direct transition to the LISTEN
              state from the SYN-RCVD state."
      ::= { tcp 7 }

When I lookup into RFC793, I found that the state change should occured
under following condition:
  1. SYN-SENT -> CLOSED
     a) Received ACK,RST segment when SYN-SENT state.

  2. SYN-RCVD -> CLOSED
     b) Received SYN segment when SYN-RCVD state(came from LISTEN).
     c) Received RST segment when SYN-RCVD state(came from SYN-SENT).
     d) Received SYN segment when SYN-RCVD state(came from SYN-SENT).

  3. SYN-RCVD -> LISTEN
     e) Received RST segment when SYN-RCVD state(came from LISTEN).

In my test, those direct state transition can not be counted to
tcpAttemptFails.

Signed-off-by: Wei Yongjun <yjwei@nanjing-fnst.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 0720bddff1e..7a093d0aa0f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -914,6 +914,9 @@ static inline void tcp_set_state(struct sock *sk, int state)
 
 static inline void tcp_done(struct sock *sk)
 {
+        if(sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
+                TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
+
         tcp_set_state(sk, TCP_CLOSE);
         tcp_clear_xmit_timers(sk);