Commit 4ce7fb8d authored Apr 13, 2025 by Matthieu Baerts (NGI0) Committed by Jakub Kicinski Apr 15, 2025

mptcp: add MPJoinRejected MIB counter



This counter is useful to understand why some paths are rejected, and
not created as expected.

It is incremented when receiving a connection request, if the PM didn't
allow the creation of new subflows.

Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250413-net-next-mptcp-sched-mib-sft-misc-v2-5-0f83a4350150@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 60cbf315

net/mptcp/mib.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -28,6 +28,7 @@ static const struct snmp_mib mptcp_snmp_list[] = {
		SNMP_MIB_ITEM("MPJoinSynAckHMacFailure", MPTCP_MIB_JOINSYNACKMAC),
		SNMP_MIB_ITEM("MPJoinAckRx", MPTCP_MIB_JOINACKRX),
		SNMP_MIB_ITEM("MPJoinAckHMacFailure", MPTCP_MIB_JOINACKMAC),
		SNMP_MIB_ITEM("MPJoinRejected", MPTCP_MIB_JOINREJECTED),
		SNMP_MIB_ITEM("MPJoinSynTx", MPTCP_MIB_JOINSYNTX),
		SNMP_MIB_ITEM("MPJoinSynTxCreatSkErr", MPTCP_MIB_JOINSYNTXCREATSKERR),
		SNMP_MIB_ITEM("MPJoinSynTxBindErr", MPTCP_MIB_JOINSYNTXBINDERR),

net/mptcp/mib.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -23,6 +23,7 @@ enum linux_mptcp_mib_field {
		MPTCP_MIB_JOINSYNACKMAC, /* HMAC was wrong on SYN/ACK + MP_JOIN */
		MPTCP_MIB_JOINACKRX, /* Received an ACK + MP_JOIN */
		MPTCP_MIB_JOINACKMAC, /* HMAC was wrong on ACK + MP_JOIN */
		MPTCP_MIB_JOINREJECTED, /* The PM rejected the JOIN request */
		MPTCP_MIB_JOINSYNTX, /* Sending a SYN + MP_JOIN */
		MPTCP_MIB_JOINSYNTXCREATSKERR, /* Not able to create a socket when sending a SYN + MP_JOIN */
		MPTCP_MIB_JOINSYNTXBINDERR, /* Not able to bind() the address when sending a SYN + MP_JOIN */

net/mptcp/protocol.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -3527,8 +3527,10 @@ bool mptcp_finish_join(struct sock *ssk)
		return true;
		}

		if (!mptcp_pm_allow_new_subflow(msk))
		if (!mptcp_pm_allow_new_subflow(msk)) {
		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_JOINREJECTED);
		goto err_prohibited;
		}

		/* If we can't acquire msk socket lock here, let the release callback
		* handle it

net/mptcp/subflow.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -247,6 +247,7 @@ static int subflow_check_req(struct request_sock *req,

		if (unlikely(req->syncookie)) {
		if (!mptcp_can_accept_new_subflow(subflow_req->msk)) {
		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINREJECTED);
		subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
		return -EPERM;
		}
		@@ -902,6 +903,7 @@ static struct sock subflow_syn_recv_sock(const struct sock sk,
		}

		if (!mptcp_can_accept_new_subflow(owner)) {
		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINREJECTED);
		subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
		goto dispose_child;
		}