Merge branch 'mptcp-fix-fallback-mib-counter-and-wrong-var-in-selftests'

Matthieu Baerts says:

====================
mptcp: fix fallback MIB counter and wrong var in selftests

Here are two fixes related to MPTCP.

The first patch fixes when the MPTcpExtMPCapableFallbackACK MIB counter
is modified: it should only be incremented when a connection was using
MPTCP options, but then a fallback to TCP has been done. This patch also
checks the counter is not incremented by mistake during the connect
selftests. This counter was wrongly incremented since its introduction
in v5.7.

The second patch fixes a wrong parsing of the 'dev' endpoint options in
the selftests: the wrong variable was used. This option was not used
before, but it is going to be soon. This issue is visible since v5.18.
====================

Link: https://lore.kernel.org/r/20240329-upstream-net-20240329-fallback-mib-v1-0-324a8981da48@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/mptcp/protocol.c

@@ -3937,8 +3937,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 				mptcp_set_state(newsk, TCP_CLOSE);
 		}
 	} else {
-		MPTCP_INC_STATS(sock_net(ssk),
-				MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
 tcpfallback:
 		newsk->sk_kern_sock = kern;
 		lock_sock(newsk);

net/mptcp/subflow.c

@@ -905,6 +905,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	return child;
 
 fallback:
+	if (fallback)
+		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
 	mptcp_subflow_drop_ctx(child);
 	return child;
 }

tools/testing/selftests/net/mptcp/mptcp_connect.sh

@@ -383,12 +383,14 @@ do_transfer()
 	local stat_cookierx_last
 	local stat_csum_err_s
 	local stat_csum_err_c
+	local stat_tcpfb_last_l
 	stat_synrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
 	stat_ackrx_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
 	stat_cookietx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
 	stat_cookierx_last=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
 	stat_csum_err_s=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtDataCsumErr")
 	stat_csum_err_c=$(mptcp_lib_get_counter "${connector_ns}" "MPTcpExtDataCsumErr")
+	stat_tcpfb_last_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableFallbackACK")
 
 	timeout ${timeout_test} \
 		ip netns exec ${listener_ns} \
@@ -457,11 +459,13 @@ do_transfer()
 	local stat_cookietx_now
 	local stat_cookierx_now
 	local stat_ooo_now
+	local stat_tcpfb_now_l
 	stat_synrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
 	stat_ackrx_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
 	stat_cookietx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesSent")
 	stat_cookierx_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtSyncookiesRecv")
 	stat_ooo_now=$(mptcp_lib_get_counter "${listener_ns}" "TcpExtTCPOFOQueue")
+	stat_tcpfb_now_l=$(mptcp_lib_get_counter "${listener_ns}" "MPTcpExtMPCapableFallbackACK")
 
 	expect_synrx=$((stat_synrx_last_l))
 	expect_ackrx=$((stat_ackrx_last_l))
@@ -508,6 +512,11 @@ do_transfer()
 		fi
 	fi
 
+	if [ ${stat_ooo_now} -eq 0 ] && [ ${stat_tcpfb_last_l} -ne ${stat_tcpfb_now_l} ]; then
+		mptcp_lib_pr_fail "unexpected fallback to TCP"
+		rets=1
+	fi
+
 	if [ $cookies -eq 2 ];then
 		if [ $stat_cookietx_last -ge $stat_cookietx_now ] ;then
 			extra+=" WARN: CookieSent: did not advance"

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -729,7 +729,7 @@ pm_nl_check_endpoint()
 			[ -n "$_flags" ]; flags="flags $_flags"
 			shift
 		elif [ $1 = "dev" ]; then
-			[ -n "$2" ]; dev="dev $1"
+			[ -n "$2" ]; dev="dev $2"
 			shift
 		elif [ $1 = "id" ]; then
 			_id=$2
@@ -3610,6 +3610,8 @@ endpoint_tests()
 		local tests_pid=$!
 
 		wait_mpj $ns2
+		pm_nl_check_endpoint "creation" \
+			$ns2 10.0.2.2 id 2 flags subflow dev ns2eth2
 		chk_subflow_nr "before delete" 2
 		chk_mptcp_info subflows 1 subflows 1