From a46d0ea5c94205f40ecf912d1bb7806a8a64704f Mon Sep 17 00:00:00 2001 From: Jason Xing Date: Tue, 4 Jun 2024 01:02:16 +0800 Subject: [PATCH 1/2] 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); } From 9633e9377e6af0244f7381e86b9aac5276f5be97 Mon Sep 17 00:00:00 2001 From: Jason Xing Date: Tue, 4 Jun 2024 01:02:17 +0800 Subject: [PATCH 2/2] mptcp: count CLOSE-WAIT sockets for MPTCP_MIB_CURRESTAB Like previous patch does in TCP, we need to adhere to RFC 1213: "tcpCurrEstab OBJECT-TYPE ... The number of TCP connections for which the current state is either ESTABLISHED or CLOSE- WAIT." So let's consider CLOSE-WAIT sockets. The logic of counting When we increment the counter? a) Only if we change the state to ESTABLISHED. 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. Fixes: d9cd27b8cd19 ("mptcp: add CurrEstab MIB counter support") Signed-off-by: Jason Xing Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: David S. Miller --- net/mptcp/protocol.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7d44196ec5b6..96b113854bd3 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2916,9 +2916,14 @@ void mptcp_set_state(struct sock *sk, int state) if (oldstate != TCP_ESTABLISHED) MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB); break; - + case TCP_CLOSE_WAIT: + /* Unlike TCP, MPTCP sk would not have the TCP_SYN_RECV state: + * MPTCP "accepted" sockets will be created later on. So no + * transition from TCP_SYN_RECV to TCP_CLOSE_WAIT. + */ + break; default: - if (oldstate == TCP_ESTABLISHED) + if (oldstate == TCP_ESTABLISHED || oldstate == TCP_CLOSE_WAIT) MPTCP_DEC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB); }