diff mbox series

[net,v5,2/2] mptcp: count CLOSE-WAIT sockets for MPTCP_MIB_CURRESTAB

Message ID 20240603170217.6243-3-kerneljasonxing@gmail.com (mailing list archive)
State Mainlined, archived
Delegated to: Matthieu Baerts
Headers show
Series tcp/mptcp: count CLOSE-WAIT for CurrEstab | expand

Checks

Context Check Description
matttbe/build success Build and static analysis OK
matttbe/checkpatch success total: 0 errors, 0 warnings, 0 checks, 16 lines checked
matttbe/shellcheck success MPTCP selftests files have not been modified
matttbe/KVM_Validation__normal success Success! ✅
matttbe/KVM_Validation__debug success Success! ✅
matttbe/KVM_Validation__btf__only_bpftest_all_ success Success! ✅

Commit Message

Jason Xing June 3, 2024, 5:02 p.m. UTC 
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.

Fixes: d9cd27b8cd19 ("mptcp: add CurrEstab MIB counter support")
Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 net/mptcp/protocol.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Comments

Matthieu Baerts (NGI0) June 3, 2024, 7:48 p.m. UTC | #1 
Hi Jason,

On 03/06/2024 19:02, 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 the update!

Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

Cheers,
Matt
diff mbox series

Patch

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);
 	}