[PATCH v4 0/2] mptcp: per-event MIB counters for MPTCP_RST_EMPTCP

[PATCH v4 0/2] mptcp: per-event MIB counters for MPTCP_RST_EMPTCP

[Shardul Bankar]

MPTCP_RST_EMPTCP (reset reason 1) is currently used as a catch-all for
several distinct conditions across subflow setup, authentication, and
data-path validation.  This series adds per-event MIB counters at each
of those use sites and validates them from mptcp_join.sh.

Patch 1 adds seven counters (MD5SigReset, MPJoinSynAckNoMPJoin,
MPJoinAckNoMPJoin, MPJoinAckNoCtx, MPJoinNoIdFound, DssReset,
MPJoinNotEstablished) and increments them in mib.c/mib.h, subflow.c and
protocol.c.

Patch 2 adds named env-var expectations for each counter: the
JOIN-related ones in chk_join_nr() and the two reset ones in
chk_rst_nr(), both on fixed namespaces.  It also adds one test inside
signal_address_tests that triggers MPJoinSynAckNoMPJoin from the
existing ns1/ns2 setup.

v4 (this version):
  patch 1: add MPJoinNoIdFound for an MP_JOIN that carries a valid token
           but for which the path manager returns no local id; it
           reaches the same MPTCP_RST_EMPTCP that MPJoinNoTokenFound
           only counts the no-token half of (Matt).
  patch 2: move the MPJoin* checks into chk_join_nr() with fixed
           namespaces, leaving only MD5SigReset and DssReset in
           chk_rst_nr() (Matt); rename the env vars (join_* / rst_md5sig
           / rst_dss); the new test uses mptcp_lib_wait_local_port_listen()
           and asserts with chk_join_nr().
v3: https://lore.kernel.org/all/20260512103331.1934343-1-shardul.b@mpiricsoftware.com/
v2: https://lore.kernel.org/all/20260509183335.969018-1-shardul.b@mpiricsoftware.com/
v1: https://lore.kernel.org/all/20260421095646.3741956-1-shardul.b@mpiricsoftware.com/

Shardul Bankar (2):
  mptcp: add per-event MIB counters for MPTCP_RST_EMPTCP resets
  selftests: mptcp: check per-event MPTCP_RST_EMPTCP counters

 net/mptcp/mib.c                               |  7 ++
 net/mptcp/mib.h                               |  7 ++
 net/mptcp/protocol.c                          |  1 +
 net/mptcp/subflow.c                           | 10 ++
 .../testing/selftests/net/mptcp/mptcp_join.sh | 93 +++++++++++++++++++
 5 files changed, 118 insertions(+)

-- 
2.34.1

[PATCH v4 1/2] mptcp: add per-event MIB counters for MPTCP_RST_EMPTCP resets

[Shardul Bankar]

MPTCP_RST_EMPTCP (reset reason 1) is used as a catch-all for several
distinct error conditions across subflow setup, authentication, and
data-path validation.  The existing MPRstTx/MPRstRx counters only
track aggregate reset volume, making it difficult to diagnose which
code path is triggering subflow resets in production.

Add per-event MIB counters covering each MPTCP_RST_EMPTCP use site
that is not already covered by an existing counter, named after the
underlying event or condition rather than the reset action:

  MD5SigReset           MD5SIG enabled on listener (incompatible)
  MPJoinSynAckNoMPJoin  SYN/ACK missing MP_JOIN option
  MPJoinAckNoMPJoin     server-side ACK missing MP_JOIN option
                          (fallback path, MPJoin required)
  MPJoinAckNoCtx        server-side ACK with no subflow context
  MPJoinNoIdFound       MP_JOIN with a valid token but no PM local ID
  DssReset              data mapping invalid (also fires on
                          MAPPING_NODSS / EMIDDLEBOX path)
  MPJoinNotEstablished  JOIN attempted on a not-fully-established msk

MPJoinNoIdFound covers the second half of the no-msk MP_JOIN reset:
the existing MPJoinNoTokenFound (MPTCP_MIB_JOINNOTOKEN) only counts the
missing-token case in subflow_token_join_request(), while a JOIN that
carries a valid token but for which the path manager returns no local
id reaches the same MPTCP_RST_EMPTCP in subflow_check_req() uncounted.

The aggregate MPRstTx/MPRstRx counters are unchanged.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/511
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
---
 net/mptcp/mib.c      |  7 +++++++
 net/mptcp/mib.h      |  7 +++++++
 net/mptcp/protocol.c |  1 +
 net/mptcp/subflow.c  | 10 ++++++++++
 4 files changed, 25 insertions(+)

diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c
index d9bd4f4afcc0e..a43893456a2e8 100644
--- a/net/mptcp/mib.c
+++ b/net/mptcp/mib.c
@@ -21,14 +21,19 @@ static const struct snmp_mib mptcp_snmp_list[] = {
 	SNMP_MIB_ITEM("MPFallbackTokenInit", MPTCP_MIB_TOKENFALLBACKINIT),
 	SNMP_MIB_ITEM("MPTCPRetrans", MPTCP_MIB_RETRANSSEGS),
 	SNMP_MIB_ITEM("MPJoinNoTokenFound", MPTCP_MIB_JOINNOTOKEN),
+	SNMP_MIB_ITEM("MPJoinNoIdFound", MPTCP_MIB_MPJOINNOIDFOUND),
 	SNMP_MIB_ITEM("MPJoinSynRx", MPTCP_MIB_JOINSYNRX),
 	SNMP_MIB_ITEM("MPJoinSynBackupRx", MPTCP_MIB_JOINSYNBACKUPRX),
 	SNMP_MIB_ITEM("MPJoinSynAckRx", MPTCP_MIB_JOINSYNACKRX),
 	SNMP_MIB_ITEM("MPJoinSynAckBackupRx", MPTCP_MIB_JOINSYNACKBACKUPRX),
 	SNMP_MIB_ITEM("MPJoinSynAckHMacFailure", MPTCP_MIB_JOINSYNACKMAC),
+	SNMP_MIB_ITEM("MPJoinSynAckNoMPJoin", MPTCP_MIB_MPJOINSYNACKNOMPJOIN),
 	SNMP_MIB_ITEM("MPJoinAckRx", MPTCP_MIB_JOINACKRX),
 	SNMP_MIB_ITEM("MPJoinAckHMacFailure", MPTCP_MIB_JOINACKMAC),
+	SNMP_MIB_ITEM("MPJoinAckNoMPJoin", MPTCP_MIB_MPJOINACKNOMPJOIN),
+	SNMP_MIB_ITEM("MPJoinAckNoCtx", MPTCP_MIB_MPJOINACKNOCTX),
 	SNMP_MIB_ITEM("MPJoinRejected", MPTCP_MIB_JOINREJECTED),
+	SNMP_MIB_ITEM("MPJoinNotEstablished", MPTCP_MIB_MPJOINNOTESTABLISHED),
 	SNMP_MIB_ITEM("MPJoinSynTx", MPTCP_MIB_JOINSYNTX),
 	SNMP_MIB_ITEM("MPJoinSynTxCreatSkErr", MPTCP_MIB_JOINSYNTXCREATSKERR),
 	SNMP_MIB_ITEM("MPJoinSynTxBindErr", MPTCP_MIB_JOINSYNTXBINDERR),
@@ -81,7 +86,9 @@ static const struct snmp_mib mptcp_snmp_list[] = {
 	SNMP_MIB_ITEM("Blackhole", MPTCP_MIB_BLACKHOLE),
 	SNMP_MIB_ITEM("MPCapableDataFallback", MPTCP_MIB_MPCAPABLEDATAFALLBACK),
 	SNMP_MIB_ITEM("MD5SigFallback", MPTCP_MIB_MD5SIGFALLBACK),
+	SNMP_MIB_ITEM("MD5SigReset", MPTCP_MIB_MD5SIGRESET),
 	SNMP_MIB_ITEM("DssFallback", MPTCP_MIB_DSSFALLBACK),
+	SNMP_MIB_ITEM("DssReset", MPTCP_MIB_DSSRESET),
 	SNMP_MIB_ITEM("SimultConnectFallback", MPTCP_MIB_SIMULTCONNFALLBACK),
 	SNMP_MIB_ITEM("FallbackFailed", MPTCP_MIB_FALLBACKFAILED),
 	SNMP_MIB_ITEM("WinProbe", MPTCP_MIB_WINPROBE),
diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h
index 18f35f7e0a2d4..18bcd8c749adc 100644
--- a/net/mptcp/mib.h
+++ b/net/mptcp/mib.h
@@ -16,14 +16,19 @@ enum linux_mptcp_mib_field {
 	MPTCP_MIB_TOKENFALLBACKINIT,	/* Could not init/allocate token */
 	MPTCP_MIB_RETRANSSEGS,		/* Segments retransmitted at the MPTCP-level */
 	MPTCP_MIB_JOINNOTOKEN,		/* Received MP_JOIN but the token was not found */
+	MPTCP_MIB_MPJOINNOIDFOUND,	/* Received MP_JOIN but no local ID was found */
 	MPTCP_MIB_JOINSYNRX,		/* Received a SYN + MP_JOIN */
 	MPTCP_MIB_JOINSYNBACKUPRX,	/* Received a SYN + MP_JOIN + backup flag */
 	MPTCP_MIB_JOINSYNACKRX,		/* Received a SYN/ACK + MP_JOIN */
 	MPTCP_MIB_JOINSYNACKBACKUPRX,	/* Received a SYN/ACK + MP_JOIN + backup flag */
 	MPTCP_MIB_JOINSYNACKMAC,	/* HMAC was wrong on SYN/ACK + MP_JOIN */
+	MPTCP_MIB_MPJOINSYNACKNOMPJOIN,	/* MP_RST: missing MP_JOIN in SYN/ACK */
 	MPTCP_MIB_JOINACKRX,		/* Received an ACK + MP_JOIN */
 	MPTCP_MIB_JOINACKMAC,		/* HMAC was wrong on ACK + MP_JOIN */
+	MPTCP_MIB_MPJOINACKNOMPJOIN,	/* MP_RST: missing MP_JOIN in ACK */
+	MPTCP_MIB_MPJOINACKNOCTX,	/* MP_RST: no subflow context on ACK */
 	MPTCP_MIB_JOINREJECTED,		/* The PM rejected the JOIN request */
+	MPTCP_MIB_MPJOINNOTESTABLISHED,	/* MP_RST: JOIN on not-fully-established msk */
 	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 */
@@ -84,7 +89,9 @@ enum linux_mptcp_mib_field {
 					 * established packet
 					 */
 	MPTCP_MIB_MD5SIGFALLBACK,	/* Conflicting TCP option enabled */
+	MPTCP_MIB_MD5SIGRESET,		/* MP_RST: MD5SIG enabled on listener */
 	MPTCP_MIB_DSSFALLBACK,		/* Bad or missing DSS */
+	MPTCP_MIB_DSSRESET,		/* MP_RST: bad data mapping */
 	MPTCP_MIB_SIMULTCONNFALLBACK,	/* Simultaneous connect */
 	MPTCP_MIB_FALLBACKFAILED,	/* Can't fallback due to msk status */
 	MPTCP_MIB_WINPROBE,		/* MPTCP-level zero window probe */
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index a4f7e99b30dbc..3e035f368038a 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3976,6 +3976,7 @@ bool mptcp_finish_join(struct sock *ssk)
 
 	/* mptcp socket already closing? */
 	if (!mptcp_is_fully_established(parent)) {
+		MPTCP_INC_STATS(sock_net(parent), MPTCP_MIB_MPJOINNOTESTABLISHED);
 		subflow->reset_reason = MPTCP_RST_EMPTCP;
 		return false;
 	}
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 8e386899ceb98..6e8932f5c9ed0 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -96,6 +96,7 @@ static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
 
 	local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
 	if (local_id < 0) {
+		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPJOINNOIDFOUND);
 		sock_put((struct sock *)msk);
 		return NULL;
 	}
@@ -160,6 +161,7 @@ static int subflow_check_req(struct request_sock *req,
 	 * TCP option space.
 	 */
 	if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) {
+		MPTCP_INC_STATS(sock_net(sk_listener), MPTCP_MIB_MD5SIGRESET);
 		subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 		return -EINVAL;
 	}
@@ -568,6 +570,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 		u8 hmac[SHA256_DIGEST_SIZE];
 
 		if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) {
+			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPJOINSYNACKNOMPJOIN);
 			subflow->reset_reason = MPTCP_RST_EMPTCP;
 			goto do_reset;
 		}
@@ -870,6 +873,12 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 		 */
 		if (!ctx || fallback) {
 			if (fallback_is_fatal) {
+				if (!ctx)
+					MPTCP_INC_STATS(sock_net(sk),
+							MPTCP_MIB_MPJOINACKNOCTX);
+				else
+					MPTCP_INC_STATS(sock_net(sk),
+							MPTCP_MIB_MPJOINACKNOMPJOIN);
 				subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 				goto dispose_child;
 			}
@@ -1421,6 +1430,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
 			 * subflow_error_report() will introduce the appropriate barriers
 			 */
 			subflow->reset_transient = 0;
+			MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSRESET);
 			subflow->reset_reason = status == MAPPING_NODSS ?
 						MPTCP_RST_EMIDDLEBOX :
 						MPTCP_RST_EMPTCP;
-- 
2.34.1

[PATCH v4 2/2] selftests: mptcp: check per-event MPTCP_RST_EMPTCP counters

[Shardul Bankar]

Add named env-var expectations for each per-event MPTCP_RST_EMPTCP
counter, matching the pattern used by the existing JOIN/RST checks.
Each defaults to 0 and is checked silently on success; a mismatch prints
a check line and fails the test.  Counters absent from the running
kernel are skipped silently so older kernels do not false-fail.

The JOIN-related counters (MPJoinSynAckNoMPJoin, MPJoinAckNoMPJoin,
MPJoinAckNoCtx, MPJoinNotEstablished, MPJoinNoIdFound) are checked in
chk_join_nr() on fixed namespaces; the two remaining reset counters
(MD5SigReset, DssReset) stay in chk_rst_nr().

Add a test at the end of signal_address_tests that triggers
MPJoinSynAckNoMPJoin: ns1 signals an address that is already bound on
the client (ns2), where a TCP-only mptcp_connect listener is started.
The client's MP_JOIN routes locally to the TCP listener, which responds
with a plain SYN/ACK without the MP_JOIN option, and the new counter
increments on the client side.

Other per-event counters (MD5SigReset, MPJoinAckNoMPJoin, MPJoinAckNoCtx,
DssReset, MPJoinNotEstablished, MPJoinNoIdFound) are not currently
reachable from mptcp_join.sh; the env-var hooks are in place for future
tests to set expectations explicitly.

Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
---
 .../testing/selftests/net/mptcp/mptcp_join.sh | 93 +++++++++++++++++++
 1 file changed, 93 insertions(+)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 550a6b6117a98..25768e700067c 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -75,6 +75,14 @@ unset join_syn_tx
 unset join_create_err
 unset join_bind_err
 unset join_connect_err
+unset join_synack_no_mpjoin
+unset join_ack_no_mpjoin
+unset join_ack_no_ctx
+unset join_not_established
+unset join_no_id_found
+
+unset rst_md5sig
+unset rst_dss
 
 unset fb_ns1
 unset fb_ns2
@@ -1353,6 +1361,8 @@ chk_rst_nr()
 	local rst_tx=$1
 	local rst_rx=$2
 	local ns_invert=${3:-""}
+	local md5sig=${rst_md5sig:-0}
+	local dss=${rst_dss:-0}
 	local count
 	local ns_tx=$ns1
 	local ns_rx=$ns2
@@ -1389,6 +1399,21 @@ chk_rst_nr()
 	else
 		print_ok
 	fi
+
+	# MPTCP_RST_EMPTCP reset-event counters; default 0, gated on
+	# availability.  Fixed namespaces: MD5SigReset fires on the listener
+	# (server), DssReset on the data receiver (client).
+	count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtMD5SigReset")
+	if [ -n "$count" ] && [ "$count" != "$md5sig" ]; then
+		print_check "MD5SigReset"
+		fail_test "got $count MD5SigReset expected $md5sig"
+	fi
+
+	count=$(mptcp_lib_get_counter ${ns2} "MPTcpExtDssReset")
+	if [ -n "$count" ] && [ "$count" != "$dss" ]; then
+		print_check "DssReset"
+		fail_test "got $count DssReset expected $dss"
+	fi
 }
 
 chk_infi_nr()
@@ -1587,6 +1612,11 @@ chk_join_nr()
 	local rst_nr=${join_rst_nr:-0}
 	local infi_nr=${join_infi_nr:-0}
 	local corrupted_pkts=${join_corrupted_pkts:-0}
+	local synack_no_mpjoin=${join_synack_no_mpjoin:-0}
+	local ack_no_mpjoin=${join_ack_no_mpjoin:-0}
+	local ack_no_ctx=${join_ack_no_ctx:-0}
+	local not_established=${join_not_established:-0}
+	local no_id_found=${join_no_id_found:-0}
 	local rc=${KSFT_PASS}
 	local count
 	local with_cookie
@@ -1655,6 +1685,44 @@ chk_join_nr()
 		fail_test "got $count JOIN[s] syn rejected expected $syn_rej"
 	fi
 
+	# Per-event MPTCP_RST_EMPTCP JOIN counters; default 0, gated on
+	# availability.  Fixed namespaces: the *SynAck* one fires on the
+	# client receiving the SYN/ACK, the others on the server.
+	count=$(mptcp_lib_get_counter ${ns2} "MPTcpExtMPJoinSynAckNoMPJoin")
+	if [ -n "$count" ] && [ "$count" != "$synack_no_mpjoin" ]; then
+		rc=${KSFT_FAIL}
+		print_check "synack no mpjoin"
+		fail_test "got $count JOIN[s] synack no mpjoin expected $synack_no_mpjoin"
+	fi
+
+	count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtMPJoinAckNoMPJoin")
+	if [ -n "$count" ] && [ "$count" != "$ack_no_mpjoin" ]; then
+		rc=${KSFT_FAIL}
+		print_check "ack no mpjoin"
+		fail_test "got $count JOIN[s] ack no mpjoin expected $ack_no_mpjoin"
+	fi
+
+	count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtMPJoinAckNoCtx")
+	if [ -n "$count" ] && [ "$count" != "$ack_no_ctx" ]; then
+		rc=${KSFT_FAIL}
+		print_check "ack no ctx"
+		fail_test "got $count JOIN[s] ack no ctx expected $ack_no_ctx"
+	fi
+
+	count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtMPJoinNotEstablished")
+	if [ -n "$count" ] && [ "$count" != "$not_established" ]; then
+		rc=${KSFT_FAIL}
+		print_check "join not established"
+		fail_test "got $count JOIN[s] not established expected $not_established"
+	fi
+
+	count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtMPJoinNoIdFound")
+	if [ -n "$count" ] && [ "$count" != "$no_id_found" ]; then
+		rc=${KSFT_FAIL}
+		print_check "join no id found"
+		fail_test "got $count JOIN[s] no id found expected $no_id_found"
+	fi
+
 	print_results "join Rx" ${rc}
 
 	join_syn_tx="${join_syn_tx:-${syn_nr}}" \
@@ -2359,6 +2427,31 @@ signal_address_tests()
 			chk_add_nr 4 4
 		fi
 	fi
+
+	# signalled address belongs to the client, where a TCP-only
+	# listener is bound at it: the client's MP_JOIN routes locally
+	# to the listener and receives a SYN/ACK without MP_JOIN.
+	# MPJoinSynAckNoMPJoin increments on the client side.
+	if reset "signal address, TCP-only listener on client"; then
+		local extra_bind
+		local port
+
+		pm_nl_set_limits $ns1 0 1
+		pm_nl_set_limits $ns2 1 1
+		pm_nl_add_endpoint $ns1 10.0.2.2 flags signal
+
+		port=$(get_port)
+		ip netns exec ${ns2} ./mptcp_connect -l -t -1 -p "$port" \
+			-s TCP 10.0.2.2 &
+		extra_bind=$!
+		mptcp_lib_wait_local_port_listen "$ns2" "$port"
+
+		run_tests $ns1 $ns2 10.0.1.1
+		join_synack_no_mpjoin=1 join_syn_tx=1 \
+			chk_join_nr 0 0 0
+
+		kill ${extra_bind} 2>/dev/null
+	fi
 }
 
 laminar_endp_tests()
-- 
2.34.1

Re: [PATCH v4 0/2] mptcp: per-event MIB counters for MPTCP_RST_EMPTCP

[MPTCP CI]

Hi Shardul,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join): Success! ✅
- KVM Validation: normal (only selftest_mptcp_join): Success! ✅
- KVM Validation: debug (except selftest_mptcp_join): Success! ✅
- KVM Validation: debug (only selftest_mptcp_join): Success! ✅
- KVM Validation: btf-normal (only bpftest_all): Success! ✅
- KVM Validation: btf-debug (only bpftest_all): Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/27376133346

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/5d23d993f27c
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1110277


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-normal

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)

Re: [PATCH v4 0/2] mptcp: per-event MIB counters for MPTCP_RST_EMPTCP

[Matthieu Baerts]

Hi Shardul,

On 11/06/2026 22:32, Shardul Bankar wrote:
> MPTCP_RST_EMPTCP (reset reason 1) is currently used as a catch-all for
> several distinct conditions across subflow setup, authentication, and
> data-path validation.  This series adds per-event MIB counters at each
> of those use sites and validates them from mptcp_join.sh.
> 
> Patch 1 adds seven counters (MD5SigReset, MPJoinSynAckNoMPJoin,
> MPJoinAckNoMPJoin, MPJoinAckNoCtx, MPJoinNoIdFound, DssReset,
> MPJoinNotEstablished) and increments them in mib.c/mib.h, subflow.c and
> protocol.c.
> 
> Patch 2 adds named env-var expectations for each counter: the
> JOIN-related ones in chk_join_nr() and the two reset ones in
> chk_rst_nr(), both on fixed namespaces.  It also adds one test inside
> signal_address_tests that triggers MPJoinSynAckNoMPJoin from the
> existing ns1/ns2 setup.
> 
> v4 (this version):
>   patch 1: add MPJoinNoIdFound for an MP_JOIN that carries a valid token
>            but for which the path manager returns no local id; it
>            reaches the same MPTCP_RST_EMPTCP that MPJoinNoTokenFound
>            only counts the no-token half of (Matt).
>   patch 2: move the MPJoin* checks into chk_join_nr() with fixed
>            namespaces, leaving only MD5SigReset and DssReset in
>            chk_rst_nr() (Matt); rename the env vars (join_* / rst_md5sig
>            / rst_dss); the new test uses mptcp_lib_wait_local_port_listen()
>            and asserts with chk_join_nr().
Thank you for the v4, and sorry for the exceptionally long delay!

The new version looks good to me:

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


New patches for t/upstream:
- 4ef5be975394: mptcp: add per-event MIB counters for MPTCP_RST_EMPTCP
resets
- 69359746fd42: selftests: mptcp: check per-event MPTCP_RST_EMPTCP counters
- Results: b67053e5e63b..25452f1bb469 (export)

Tests are now in progress:

- export:
https://github.com/multipath-tcp/mptcp_net-next/commit/d53994ceed37c0dd4cd6c780d5f0a108c7f5bab2/checks

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.