Re: [PATCH net v4 2/2] mptcp: count CLOSE-WAIT sockets for MPTCP_MIB_CURRESTAB
From: Matthieu Baerts <matttbe@kernel.org>
Date: 2024-06-03 12:47:34
Also in:
mptcp
Hi Jason, On 31/05/2024 11:17, Jason Xing wrote:
From: Jason Xing <kernelxing@tencent.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.
Thank you for this modification, and for having updated the Fixes tag.
quoted hunk ↗ jump to hunk
Fixes: d9cd27b8cd19 ("mptcp: add CurrEstab MIB counter support") Signed-off-by: Jason Xing <kernelxing@tencent.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;
The modification is correct: currently, and compared to TCP, the MPTCP "accepted" socket will not go through the TCP_SYN_RECV state because it will be created later on. Still, I wonder if it would not be clearer to explicitly mention this here, and (or) in the commit message, to be able to understand why the logic is different here, compared to TCP. I don't think the SYN_RECV state will be used in the future with MPTCP sockets, but just in case, it might help to mention TCP_SYN_RECV state here. Could add a small comment here above please?
default: - if (oldstate == TCP_ESTABLISHED) + if (oldstate == TCP_ESTABLISHED || oldstate == TCP_CLOSE_WAIT) MPTCP_DEC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB); }
Cheers, Matt -- Sponsored by the NGI0 Core fund.