netdev - [PATCH net v3 2/2] mptcp: count CLOSE-WAIT sockets for MPTCP_MIB

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Message-Id: <20240530131308.59737-3-kerneljasonxing@gmail.com>
Date: Thu, 30 May 2024 21:13:08 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net,
	dsahern@...nel.org,
	matttbe@...nel.org,
	martineau@...nel.org,
	geliang@...nel.org
Cc: netdev@...r.kernel.org,
	mptcp@...ts.linux.dev,
	kerneljasonxing@...il.com,
	Jason Xing <kernelxing@...cent.com>
Subject: [PATCH net v3 2/2] mptcp: count CLOSE-WAIT sockets for MPTCP_MIB_CURRESTAB

From: Jason Xing <kernelxing@...cent.com>

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: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jason Xing <kernelxing@...cent.com>
---
 net/mptcp/protocol.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 7d44196ec5b6..6d59c1c4baba 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2916,9 +2916,10 @@ 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:
+		break;
 	default:
-		if (oldstate == TCP_ESTABLISHED)
+		if (oldstate == TCP_ESTABLISHED || oldstate == TCP_CLOSE_WAIT)
 			MPTCP_DEC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB);
 	}

-- 
2.37.3