From a46d0ea5c94205f40ecf912d1bb7806a8a64704f Mon Sep 17 00:00:00 2001 From: Jason Xing Date: Tue, 4 Jun 2024 01:02:16 +0800 Subject: tcp: count CLOSE-WAIT sockets for TCP_MIB_CURRESTAB According to RFC 1213, we should also take CLOSE-WAIT sockets into consideration: "tcpCurrEstab OBJECT-TYPE ... The number of TCP connections for which the current state is either ESTABLISHED or CLOSE- WAIT." After this, CurrEstab counter will display the total number of ESTABLISHED and CLOSE-WAIT sockets. The logic of counting When we increment the counter? a) if we change the state to ESTABLISHED. b) if we change the state from SYN-RECEIVED to CLOSE-WAIT. When we decrement the counter? a) if the socket leaves ESTABLISHED and will never go into CLOSE-WAIT, say, on the client side, changing from ESTABLISHED to FIN-WAIT-1. b) if the socket leaves CLOSE-WAIT, say, on the server side, changing from CLOSE-WAIT to LAST-ACK. Please note: there are two chances that old state of socket can be changed to CLOSE-WAIT in tcp_fin(). One is SYN-RECV, the other is ESTABLISHED. So we have to take care of the former case. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Jason Xing Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 4d8cc2ebb64c..e6790ea74877 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2649,6 +2649,10 @@ void tcp_set_state(struct sock *sk, int state) if (oldstate != TCP_ESTABLISHED) TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB); break; + case TCP_CLOSE_WAIT: + if (oldstate == TCP_SYN_RECV) + TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB); + break; case TCP_CLOSE: if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED) @@ -2660,7 +2664,7 @@ void tcp_set_state(struct sock *sk, int state) inet_put_port(sk); fallthrough; default: - if (oldstate == TCP_ESTABLISHED) + if (oldstate == TCP_ESTABLISHED || oldstate == TCP_CLOSE_WAIT) TCP_DEC_STATS(sock_net(sk), TCP_MIB_CURRESTAB); } -- cgit v1.2.3