Merge branch 'mptcp-fixes'

Matthieu Baerts says:

====================
selftests: mptcp: skip tests not supported by old kernels (part 3)

After a few years of increasing test coverage in the MPTCP selftests, we
realised [1] the last version of the selftests is supposed to run on old
kernels without issues.

Supporting older versions is not that easy for this MPTCP case: these
selftests are often validating the internals by checking packets that
are exchanged, when some MIB counters are incremented after some
actions, how connections are getting opened and closed in some cases,
etc. In other words, it is not limited to the socket interface between
the userspace and the kernelspace.

In addition to that, the current MPTCP selftests run a lot of different
sub-tests but the TAP13 protocol used in the selftests don't support
sub-tests: one failure in sub-tests implies that the whole selftest is
seen as failed at the end because sub-tests are not tracked. It is then
important to skip sub-tests not supported by old kernels.

To minimise the modifications and reduce the complexity to support old
versions, the idea is to look at external signs and skip the whole
selftest or just some sub-tests before starting them. This cannot be
applied in all cases.

Similar to the second part, this third one focuses on marking different
sub-tests as skipped if some MPTCP features are not supported. This
time, only in "mptcp_join.sh" selftest, the remaining one, is modified.
Several techniques are used here to achieve this task:

- Before starting some tests:

  - Check if a file (sysctl knob) is present: that's what patch 12/17 is
    doing for the userspace PM feature.

  - Check if a required kernel symbol is present in /proc/kallsyms:
    patches 9, 10, 14 and 15/17 are using this technique.

  - Check if it is possible to setup a particular network environment
    requiring Netfilter or TC: if the preparation step fail, the linked
    sub-test is marked as skipped. Patch 5/17 is doing that.

  - Check if a MIB counter is available: patches 7 and 13/17 do that.

  - Check if the kernel version is newer than a specific one: patch 1/17
    adds some helpers in mptcp_lib.sh to ease its use. That's not ideal
    and it is only used as last resort but as mentioned above, it is
    important to skip tests if they are not supported not to have the
    whole selftest always being marked as failed on old kernels. Patches
    11 and 17/17 are checking the kernel version. An alternative would
    be to ignore the results for some sub-tests but that's not ideal
    too. Note that SELFTESTS_MPTCP_LIB_NO_KVERSION_CHECK env var can be
    set to 1 not to skip these tests if the running kernel doesn't have
    a supported version.

- After having launched the tests:

  - Adapt the expectations depending on the presence of a kernel symbol
    (patch 6/17) or a kernel version (patch 8/17).

  - Check is a MIB counter is available and skip the verification if
    not. Patch 4/17 is using this technique.

Before skipping tests, SELFTESTS_MPTCP_LIB_EXPECT_ALL_FEATURES env var
value is checked: if it is set to 1, the test is marked as "failed"
instead of "skipped". MPTCP public CI expects to have all features
supported and it sets this env var to 1 to catch regressions in these
new checks.

Patch 2/17 uses 'iptables-legacy' if available because it might be
needed when using an older kernel not supporting iptables-nft.

Patch 3/17 adds some helpers used in the other patches mentioned to
easily mark sub-tests as skipped.

Patch 16/17 uniforms MPTCP Join "listener" tests: it was imported code
from userspace_pm.sh but without using the "code style" and ways of
using tools and printing messages from MPTCP Join selftest.

Link: https://lore.kernel.org/stable/CA+G9fYtDGpgT4dckXD-y-N92nqUxuvue_7AtDdBcHrbOMsDZLg@mail.gmail.com/ [1]
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/368
====================

Link: https://lore.kernel.org/r/20230609-upstream-net-20230610-mptcp-selftests-support-old-kernels-part-3-v1-0-2896fe2ee8a3@tessares.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 354 insertions, 185 deletions

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 29f0c99d9a466..0ae8cafde439f 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -25,6 +25,8 @@ capout=""
 ns1=""
 ns2=""
 ksft_skip=4
+iptables="iptables"
+ip6tables="ip6tables"
 timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
 capture=0
@@ -82,7 +84,7 @@ init_partial()
 		ip netns add $netns || exit $ksft_skip
 		ip -net $netns link set lo up
 		ip netns exec $netns sysctl -q net.mptcp.enabled=1
-		ip netns exec $netns sysctl -q net.mptcp.pm_type=0
+		ip netns exec $netns sysctl -q net.mptcp.pm_type=0 2>/dev/null || true
 		ip netns exec $netns sysctl -q net.ipv4.conf.all.rp_filter=0
 		ip netns exec $netns sysctl -q net.ipv4.conf.default.rp_filter=0
 		if [ $checksum -eq 1 ]; then
@@ -140,13 +142,18 @@ cleanup_partial()
 check_tools()
 {
 	mptcp_lib_check_mptcp
+	mptcp_lib_check_kallsyms
 
 	if ! ip -Version &> /dev/null; then
 		echo "SKIP: Could not run test without ip tool"
 		exit $ksft_skip
 	fi
 
-	if ! iptables -V &> /dev/null; then
+	# Use the legacy version if available to support old kernel versions
+	if iptables-legacy -V &> /dev/null; then
+		iptables="iptables-legacy"
+		ip6tables="ip6tables-legacy"
+	elif ! iptables -V &> /dev/null; then
 		echo "SKIP: Could not run all tests without iptables tool"
 		exit $ksft_skip
 	fi
@@ -185,6 +192,32 @@ cleanup()
 	cleanup_partial
 }
 
+# $1: msg
+print_title()
+{
+	printf "%03u %-36s %s" "${TEST_COUNT}" "${TEST_NAME}" "${1}"
+}
+
+# [ $1: fail msg ]
+mark_as_skipped()
+{
+	local msg="${1:-"Feature not supported"}"
+
+	mptcp_lib_fail_if_expected_feature "${msg}"
+
+	print_title "[ skip ] ${msg}"
+	printf "\n"
+}
+
+# $@: condition
+continue_if()
+{
+	if ! "${@}"; then
+		mark_as_skipped
+		return 1
+	fi
+}
+
 skip_test()
 {
 	if [ "${#only_tests_ids[@]}" -eq 0 ] && [ "${#only_tests_names[@]}" -eq 0 ]; then
@@ -228,6 +261,19 @@ reset()
 	return 0
 }
 
+# $1: test name ; $2: counter to check
+reset_check_counter()
+{
+	reset "${1}" || return 1
+
+	local counter="${2}"
+
+	if ! nstat -asz "${counter}" | grep -wq "${counter}"; then
+		mark_as_skipped "counter '${counter}' is not available"
+		return 1
+	fi
+}
+
 # $1: test name
 reset_with_cookies()
 {
@@ -247,17 +293,21 @@ reset_with_add_addr_timeout()
 
 	reset "${1}" || return 1
 
-	tables="iptables"
+	tables="${iptables}"
 	if [ $ip -eq 6 ]; then
-		tables="ip6tables"
+		tables="${ip6tables}"
 	fi
 
 	ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=1
-	ip netns exec $ns2 $tables -A OUTPUT -p tcp \
-		-m tcp --tcp-option 30 \
-		-m bpf --bytecode \
-		"$CBPF_MPTCP_SUBOPTION_ADD_ADDR" \
-		-j DROP
+
+	if ! ip netns exec $ns2 $tables -A OUTPUT -p tcp \
+			-m tcp --tcp-option 30 \
+			-m bpf --bytecode \
+			"$CBPF_MPTCP_SUBOPTION_ADD_ADDR" \
+			-j DROP; then
+		mark_as_skipped "unable to set the 'add addr' rule"
+		return 1
+	fi
 }
 
 # $1: test name
@@ -301,22 +351,17 @@ reset_with_allow_join_id0()
 #     tc action pedit offset 162 out of bounds
 #
 # Netfilter is used to mark packets with enough data.
-reset_with_fail()
+setup_fail_rules()
 {
-	reset "${1}" || return 1
-
-	ip netns exec $ns1 sysctl -q net.mptcp.checksum_enabled=1
-	ip netns exec $ns2 sysctl -q net.mptcp.checksum_enabled=1
-
 	check_invert=1
 	validate_checksum=1
-	local i="$2"
-	local ip="${3:-4}"
+	local i="$1"
+	local ip="${2:-4}"
 	local tables
 
-	tables="iptables"
+	tables="${iptables}"
 	if [ $ip -eq 6 ]; then
-		tables="ip6tables"
+		tables="${ip6tables}"
 	fi
 
 	ip netns exec $ns2 $tables \
@@ -326,15 +371,32 @@ reset_with_fail()
 		-p tcp \
 		-m length --length 150:9999 \
 		-m statistic --mode nth --packet 1 --every 99999 \
-		-j MARK --set-mark 42 || exit 1
+		-j MARK --set-mark 42 || return ${ksft_skip}
 
-	tc -n $ns2 qdisc add dev ns2eth$i clsact || exit 1
+	tc -n $ns2 qdisc add dev ns2eth$i clsact || return ${ksft_skip}
 	tc -n $ns2 filter add dev ns2eth$i egress \
 		protocol ip prio 1000 \
 		handle 42 fw \
 		action pedit munge offset 148 u8 invert \
 		pipe csum tcp \
-		index 100 || exit 1
+		index 100 || return ${ksft_skip}
+}
+
+reset_with_fail()
+{
+	reset_check_counter "${1}" "MPTcpExtInfiniteMapTx" || return 1
+	shift
+
+	ip netns exec $ns1 sysctl -q net.mptcp.checksum_enabled=1
+	ip netns exec $ns2 sysctl -q net.mptcp.checksum_enabled=1
+
+	local rc=0
+	setup_fail_rules "${@}" || rc=$?
+
+	if [ ${rc} -eq ${ksft_skip} ]; then
+		mark_as_skipped "unable to set the 'fail' rules"
+		return 1
+	fi
 }
 
 reset_with_events()
@@ -349,6 +411,25 @@ reset_with_events()
 	evts_ns2_pid=$!
 }
 
+reset_with_tcp_filter()
+{
+	reset "${1}" || return 1
+	shift
+
+	local ns="${!1}"
+	local src="${2}"
+	local target="${3}"
+
+	if ! ip netns exec "${ns}" ${iptables} \
+			-A INPUT \
+			-s "${src}" \
+			-p tcp \
+			-j "${target}"; then
+		mark_as_skipped "unable to set the filter rules"
+		return 1
+	fi
+}
+
 fail_test()
 {
 	ret=1
@@ -467,11 +548,25 @@ wait_local_port_listen()
 	done
 }
 
-rm_addr_count()
+# $1: ns ; $2: counter
+get_counter()
 {
-	local ns=${1}
+	local ns="${1}"
+	local counter="${2}"
+	local count
 
-	ip netns exec ${ns} nstat -as | grep MPTcpExtRmAddr | awk '{print $2}'
+	count=$(ip netns exec ${ns} nstat -asz "${counter}" | awk 'NR==1 {next} {print $2}')
+	if [ -z "${count}" ]; then
+		mptcp_lib_fail_if_expected_feature "${counter} counter"
+		return 1
+	fi
+
+	echo "${count}"
+}
+
+rm_addr_count()
+{
+	get_counter "${1}" "MPTcpExtRmAddr"
 }
 
 # $1: ns, $2: old rm_addr counter in $ns
@@ -494,11 +589,11 @@ wait_mpj()
 	local ns="${1}"
 	local cnt old_cnt
 
-	old_cnt=$(ip netns exec ${ns} nstat -as | grep MPJoinAckRx | awk '{print $2}')
+	old_cnt=$(get_counter ${ns} "MPTcpExtMPJoinAckRx")
 
 	local i
 	for i in $(seq 10); do
-		cnt=$(ip netns exec ${ns} nstat -as | grep MPJoinAckRx | awk '{print $2}')
+		cnt=$(get_counter ${ns} "MPTcpExtMPJoinAckRx")
 		[ "$cnt" = "${old_cnt}" ] || break
 		sleep 0.1
 	done
@@ -698,15 +793,6 @@ pm_nl_check_endpoint()
 	fi
 }
 
-filter_tcp_from()
-{
-	local ns="${1}"
-	local src="${2}"
-	local target="${3}"
-
-	ip netns exec "${ns}" iptables -A INPUT -s "${src}" -p tcp -j "${target}"
-}
-
 do_transfer()
 {
 	local listener_ns="$1"
@@ -1157,12 +1243,13 @@ chk_csum_nr()
 	fi
 
 	printf "%-${nr_blank}s %s" " " "sum"
-	count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtDataCsumErr | awk '{print $2}')
-	[ -z "$count" ] && count=0
+	count=$(get_counter ${ns1} "MPTcpExtDataCsumErr")
 	if [ "$count" != "$csum_ns1" ]; then
 		extra_msg="$extra_msg ns1=$count"
 	fi
-	if { [ "$count" != $csum_ns1 ] && [ $allow_multi_errors_ns1 -eq 0 ]; } ||
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif { [ "$count" != $csum_ns1 ] && [ $allow_multi_errors_ns1 -eq 0 ]; } ||
 	   { [ "$count" -lt $csum_ns1 ] && [ $allow_multi_errors_ns1 -eq 1 ]; }; then
 		echo "[fail] got $count data checksum error[s] expected $csum_ns1"
 		fail_test
@@ -1171,12 +1258,13 @@ chk_csum_nr()
 		echo -n "[ ok ]"
 	fi
 	echo -n " - csum  "
-	count=$(ip netns exec $ns2 nstat -as | grep MPTcpExtDataCsumErr | awk '{print $2}')
-	[ -z "$count" ] && count=0
+	count=$(get_counter ${ns2} "MPTcpExtDataCsumErr")
 	if [ "$count" != "$csum_ns2" ]; then
 		extra_msg="$extra_msg ns2=$count"
 	fi
-	if { [ "$count" != $csum_ns2 ] && [ $allow_multi_errors_ns2 -eq 0 ]; } ||
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif { [ "$count" != $csum_ns2 ] && [ $allow_multi_errors_ns2 -eq 0 ]; } ||
 	   { [ "$count" -lt $csum_ns2 ] && [ $allow_multi_errors_ns2 -eq 1 ]; }; then
 		echo "[fail] got $count data checksum error[s] expected $csum_ns2"
 		fail_test
@@ -1218,12 +1306,13 @@ chk_fail_nr()
 	fi
 
 	printf "%-${nr_blank}s %s" " " "ftx"
-	count=$(ip netns exec $ns_tx nstat -as | grep MPTcpExtMPFailTx | awk '{print $2}')
-	[ -z "$count" ] && count=0
+	count=$(get_counter ${ns_tx} "MPTcpExtMPFailTx")
 	if [ "$count" != "$fail_tx" ]; then
 		extra_msg="$extra_msg,tx=$count"
 	fi
-	if { [ "$count" != "$fail_tx" ] && [ $allow_tx_lost -eq 0 ]; } ||
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif { [ "$count" != "$fail_tx" ] && [ $allow_tx_lost -eq 0 ]; } ||
 	   { [ "$count" -gt "$fail_tx" ] && [ $allow_tx_lost -eq 1 ]; }; then
 		echo "[fail] got $count MP_FAIL[s] TX expected $fail_tx"
 		fail_test
@@ -1233,12 +1322,13 @@ chk_fail_nr()
 	fi
 
 	echo -n " - failrx"
-	count=$(ip netns exec $ns_rx nstat -as | grep MPTcpExtMPFailRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
+	count=$(get_counter ${ns_rx} "MPTcpExtMPFailRx")
 	if [ "$count" != "$fail_rx" ]; then
 		extra_msg="$extra_msg,rx=$count"
 	fi
-	if { [ "$count" != "$fail_rx" ] && [ $allow_rx_lost -eq 0 ]; } ||
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif { [ "$count" != "$fail_rx" ] && [ $allow_rx_lost -eq 0 ]; } ||
 	   { [ "$count" -gt "$fail_rx" ] && [ $allow_rx_lost -eq 1 ]; }; then
 		echo "[fail] got $count MP_FAIL[s] RX expected $fail_rx"
 		fail_test
@@ -1270,10 +1360,11 @@ chk_fclose_nr()
 	fi
 
 	printf "%-${nr_blank}s %s" " " "ctx"
-	count=$(ip netns exec $ns_tx nstat -as | grep MPTcpExtMPFastcloseTx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	[ "$count" != "$fclose_tx" ] && extra_msg="$extra_msg,tx=$count"
-	if [ "$count" != "$fclose_tx" ]; then
+	count=$(get_counter ${ns_tx} "MPTcpExtMPFastcloseTx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$fclose_tx" ]; then
+		extra_msg="$extra_msg,tx=$count"
 		echo "[fail] got $count MP_FASTCLOSE[s] TX expected $fclose_tx"
 		fail_test
 		dump_stats=1
@@ -1282,10 +1373,11 @@ chk_fclose_nr()
 	fi
 
 	echo -n " - fclzrx"
-	count=$(ip netns exec $ns_rx nstat -as | grep MPTcpExtMPFastcloseRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	[ "$count" != "$fclose_rx" ] && extra_msg="$extra_msg,rx=$count"
-	if [ "$count" != "$fclose_rx" ]; then
+	count=$(get_counter ${ns_rx} "MPTcpExtMPFastcloseRx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$fclose_rx" ]; then
+		extra_msg="$extra_msg,rx=$count"
 		echo "[fail] got $count MP_FASTCLOSE[s] RX expected $fclose_rx"
 		fail_test
 		dump_stats=1
@@ -1316,9 +1408,10 @@ chk_rst_nr()
 	fi
 
 	printf "%-${nr_blank}s %s" " " "rtx"
-	count=$(ip netns exec $ns_tx nstat -as | grep MPTcpExtMPRstTx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ $count -lt $rst_tx ]; then
+	count=$(get_counter ${ns_tx} "MPTcpExtMPRstTx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ $count -lt $rst_tx ]; then
 		echo "[fail] got $count MP_RST[s] TX expected $rst_tx"
 		fail_test
 		dump_stats=1
@@ -1327,9 +1420,10 @@ chk_rst_nr()
 	fi
 
 	echo -n " - rstrx "
-	count=$(ip netns exec $ns_rx nstat -as | grep MPTcpExtMPRstRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" -lt "$rst_rx" ]; then
+	count=$(get_counter ${ns_rx} "MPTcpExtMPRstRx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" -lt "$rst_rx" ]; then
 		echo "[fail] got $count MP_RST[s] RX expected $rst_rx"
 		fail_test
 		dump_stats=1
@@ -1350,9 +1444,10 @@ chk_infi_nr()
 	local dump_stats
 
 	printf "%-${nr_blank}s %s" " " "itx"
-	count=$(ip netns exec $ns2 nstat -as | grep InfiniteMapTx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$infi_tx" ]; then
+	count=$(get_counter ${ns2} "MPTcpExtInfiniteMapTx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$infi_tx" ]; then
 		echo "[fail] got $count infinite map[s] TX expected $infi_tx"
 		fail_test
 		dump_stats=1
@@ -1361,9 +1456,10 @@ chk_infi_nr()
 	fi
 
 	echo -n " - infirx"
-	count=$(ip netns exec $ns1 nstat -as | grep InfiniteMapRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$infi_rx" ]; then
+	count=$(get_counter ${ns1} "MPTcpExtInfiniteMapRx")
+	if [ -z "$count" ]; then
+		echo "[skip]"
+	elif [ "$count" != "$infi_rx" ]; then
 		echo "[fail] got $count infinite map[s] RX expected $infi_rx"
 		fail_test
 		dump_stats=1
@@ -1395,9 +1491,10 @@ chk_join_nr()
 	fi
 
 	printf "%03u %-36s %s" "${TEST_COUNT}" "${title}" "syn"
-	count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMPJoinSynRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$syn_nr" ]; then
+	count=$(get_counter ${ns1} "MPTcpExtMPJoinSynRx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$syn_nr" ]; then
 		echo "[fail] got $count JOIN[s] syn expected $syn_nr"
 		fail_test
 		dump_stats=1
@@ -1407,9 +1504,10 @@ chk_join_nr()
 
 	echo -n " - synack"
 	with_cookie=$(ip netns exec $ns2 sysctl -n net.ipv4.tcp_syncookies)
-	count=$(ip netns exec $ns2 nstat -as | grep MPTcpExtMPJoinSynAckRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$syn_ack_nr" ]; then
+	count=$(get_counter ${ns2} "MPTcpExtMPJoinSynAckRx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$syn_ack_nr" ]; then
 		# simult connections exceeding the limit with cookie enabled could go up to
 		# synack validation as the conn limit can be enforced reliably only after
 		# the subflow creation
@@ -1425,9 +1523,10 @@ chk_join_nr()
 	fi
 
 	echo -n " - ack"
-	count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMPJoinAckRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$ack_nr" ]; then
+	count=$(get_counter ${ns1} "MPTcpExtMPJoinAckRx")
+	if [ -z "$count" ]; then
+		echo "[skip]"
+	elif [ "$count" != "$ack_nr" ]; then
 		echo "[fail] got $count JOIN[s] ack expected $ack_nr"
 		fail_test
 		dump_stats=1
@@ -1459,12 +1558,12 @@ chk_stale_nr()
 	local recover_nr
 
 	printf "%-${nr_blank}s %-18s" " " "stale"
-	stale_nr=$(ip netns exec $ns nstat -as | grep MPTcpExtSubflowStale | awk '{print $2}')
-	[ -z "$stale_nr" ] && stale_nr=0
-	recover_nr=$(ip netns exec $ns nstat -as | grep MPTcpExtSubflowRecover | awk '{print $2}')
-	[ -z "$recover_nr" ] && recover_nr=0
 
-	if [ $stale_nr -lt $stale_min ] ||
+	stale_nr=$(get_counter ${ns} "MPTcpExtSubflowStale")
+	recover_nr=$(get_counter ${ns} "MPTcpExtSubflowRecover")
+	if [ -z "$stale_nr" ] || [ -z "$recover_nr" ]; then
+		echo "[skip]"
+	elif [ $stale_nr -lt $stale_min ] ||
 	   { [ $stale_max -gt 0 ] && [ $stale_nr -gt $stale_max ]; } ||
 	   [ $((stale_nr - recover_nr)) -ne $stale_delta ]; then
 		echo "[fail] got $stale_nr stale[s] $recover_nr recover[s], " \
@@ -1500,12 +1599,12 @@ chk_add_nr()
 	timeout=$(ip netns exec $ns1 sysctl -n net.mptcp.add_addr_timeout)
 
 	printf "%-${nr_blank}s %s" " " "add"
-	count=$(ip netns exec $ns2 nstat -as MPTcpExtAddAddr | grep MPTcpExtAddAddr | awk '{print $2}')
-	[ -z "$count" ] && count=0
-
+	count=$(get_counter ${ns2} "MPTcpExtAddAddr")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
 	# if the test configured a short timeout tolerate greater then expected
 	# add addrs options, due to retransmissions
-	if [ "$count" != "$add_nr" ] && { [ "$timeout" -gt 1 ] || [ "$count" -lt "$add_nr" ]; }; then
+	elif [ "$count" != "$add_nr" ] && { [ "$timeout" -gt 1 ] || [ "$count" -lt "$add_nr" ]; }; then
 		echo "[fail] got $count ADD_ADDR[s] expected $add_nr"
 		fail_test
 		dump_stats=1
@@ -1514,9 +1613,10 @@ chk_add_nr()
 	fi
 
 	echo -n " - echo  "
-	count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtEchoAdd | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$echo_nr" ]; then
+	count=$(get_counter ${ns1} "MPTcpExtEchoAdd")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$echo_nr" ]; then
 		echo "[fail] got $count ADD_ADDR echo[s] expected $echo_nr"
 		fail_test
 		dump_stats=1
@@ -1526,9 +1626,10 @@ chk_add_nr()
 
 	if [ $port_nr -gt 0 ]; then
 		echo -n " - pt "
-		count=$(ip netns exec $ns2 nstat -as | grep MPTcpExtPortAdd | awk '{print $2}')
-		[ -z "$count" ] && count=0
-		if [ "$count" != "$port_nr" ]; then
+		count=$(get_counter ${ns2} "MPTcpExtPortAdd")
+		if [ -z "$count" ]; then
+			echo "[skip]"
+		elif [ "$count" != "$port_nr" ]; then
 			echo "[fail] got $count ADD_ADDR[s] with a port-number expected $port_nr"
 			fail_test
 			dump_stats=1
@@ -1537,10 +1638,10 @@ chk_add_nr()
 		fi
 
 		printf "%-${nr_blank}s %s" " " "syn"
-		count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMPJoinPortSynRx |
-			awk '{print $2}')
-		[ -z "$count" ] && count=0
-		if [ "$count" != "$syn_nr" ]; then
+		count=$(get_counter ${ns1} "MPTcpExtMPJoinPortSynRx")
+		if [ -z "$count" ]; then
+			echo -n "[skip]"
+		elif [ "$count" != "$syn_nr" ]; then
 			echo "[fail] got $count JOIN[s] syn with a different \
 				port-number expected $syn_nr"
 			fail_test
@@ -1550,10 +1651,10 @@ chk_add_nr()
 		fi
 
 		echo -n " - synack"
-		count=$(ip netns exec $ns2 nstat -as | grep MPTcpExtMPJoinPortSynAckRx |
-			awk '{print $2}')
-		[ -z "$count" ] && count=0
-		if [ "$count" != "$syn_ack_nr" ]; then
+		count=$(get_counter ${ns2} "MPTcpExtMPJoinPortSynAckRx")
+		if [ -z "$count" ]; then
+			echo -n "[skip]"
+		elif [ "$count" != "$syn_ack_nr" ]; then
 			echo "[fail] got $count JOIN[s] synack with a different \
 				port-number expected $syn_ack_nr"
 			fail_test
@@ -1563,10 +1664,10 @@ chk_add_nr()
 		fi
 
 		echo -n " - ack"
-		count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMPJoinPortAckRx |
-			awk '{print $2}')
-		[ -z "$count" ] && count=0
-		if [ "$count" != "$ack_nr" ]; then
+		count=$(get_counter ${ns1} "MPTcpExtMPJoinPortAckRx")
+		if [ -z "$count" ]; then
+			echo "[skip]"
+		elif [ "$count" != "$ack_nr" ]; then
 			echo "[fail] got $count JOIN[s] ack with a different \
 				port-number expected $ack_nr"
 			fail_test
@@ -1576,10 +1677,10 @@ chk_add_nr()
 		fi
 
 		printf "%-${nr_blank}s %s" " " "syn"
-		count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMismatchPortSynRx |
-			awk '{print $2}')
-		[ -z "$count" ] && count=0
-		if [ "$count" != "$mis_syn_nr" ]; then
+		count=$(get_counter ${ns1} "MPTcpExtMismatchPortSynRx")
+		if [ -z "$count" ]; then
+			echo -n "[skip]"
+		elif [ "$count" != "$mis_syn_nr" ]; then
 			echo "[fail] got $count JOIN[s] syn with a mismatched \
 				port-number expected $mis_syn_nr"
 			fail_test
@@ -1589,10 +1690,10 @@ chk_add_nr()
 		fi
 
 		echo -n " - ack   "
-		count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMismatchPortAckRx |
-			awk '{print $2}')
-		[ -z "$count" ] && count=0
-		if [ "$count" != "$mis_ack_nr" ]; then
+		count=$(get_counter ${ns1} "MPTcpExtMismatchPortAckRx")
+		if [ -z "$count" ]; then
+			echo "[skip]"
+		elif [ "$count" != "$mis_ack_nr" ]; then
 			echo "[fail] got $count JOIN[s] ack with a mismatched \
 				port-number expected $mis_ack_nr"
 			fail_test
@@ -1636,9 +1737,10 @@ chk_rm_nr()
 	fi
 
 	printf "%-${nr_blank}s %s" " " "rm "
-	count=$(ip netns exec $addr_ns nstat -as | grep MPTcpExtRmAddr | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$rm_addr_nr" ]; then
+	count=$(get_counter ${addr_ns} "MPTcpExtRmAddr")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$rm_addr_nr" ]; then
 		echo "[fail] got $count RM_ADDR[s] expected $rm_addr_nr"
 		fail_test
 		dump_stats=1
@@ -1647,29 +1749,27 @@ chk_rm_nr()
 	fi
 
 	echo -n " - rmsf  "
-	count=$(ip netns exec $subflow_ns nstat -as | grep MPTcpExtRmSubflow | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ -n "$simult" ]; then
+	count=$(get_counter ${subflow_ns} "MPTcpExtRmSubflow")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ -n "$simult" ]; then
 		local cnt suffix
 
-		cnt=$(ip netns exec $addr_ns nstat -as | grep MPTcpExtRmSubflow | awk '{print $2}')
+		cnt=$(get_counter ${addr_ns} "MPTcpExtRmSubflow")
 
 		# in case of simult flush, the subflow removal count on each side is
 		# unreliable
-		[ -z "$cnt" ] && cnt=0
 		count=$((count + cnt))
 		[ "$count" != "$rm_subflow_nr" ] && suffix="$count in [$rm_subflow_nr:$((rm_subflow_nr*2))]"
 		if [ $count -ge "$rm_subflow_nr" ] && \
 		   [ "$count" -le "$((rm_subflow_nr *2 ))" ]; then
-			echo "[ ok ] $suffix"
+			echo -n "[ ok ] $suffix"
 		else
 			echo "[fail] got $count RM_SUBFLOW[s] expected in range [$rm_subflow_nr:$((rm_subflow_nr*2))]"
 			fail_test
 			dump_stats=1
 		fi
-		return
-	fi
-	if [ "$count" != "$rm_subflow_nr" ]; then
+	elif [ "$count" != "$rm_subflow_nr" ]; then
 		echo "[fail] got $count RM_SUBFLOW[s] expected $rm_subflow_nr"
 		fail_test
 		dump_stats=1
@@ -1690,9 +1790,10 @@ chk_prio_nr()
 	local dump_stats
 
 	printf "%-${nr_blank}s %s" " " "ptx"
-	count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMPPrioTx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$mp_prio_nr_tx" ]; then
+	count=$(get_counter ${ns1} "MPTcpExtMPPrioTx")
+	if [ -z "$count" ]; then
+		echo -n "[skip]"
+	elif [ "$count" != "$mp_prio_nr_tx" ]; then
 		echo "[fail] got $count MP_PRIO[s] TX expected $mp_prio_nr_tx"
 		fail_test
 		dump_stats=1
@@ -1701,9 +1802,10 @@ chk_prio_nr()
 	fi
 
 	echo -n " - prx   "
-	count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMPPrioRx | awk '{print $2}')
-	[ -z "$count" ] && count=0
-	if [ "$count" != "$mp_prio_nr_rx" ]; then
+	count=$(get_counter ${ns1} "MPTcpExtMPPrioRx")
+	if [ -z "$count" ]; then
+		echo "[skip]"
+	elif [ "$count" != "$mp_prio_nr_rx" ]; then
 		echo "[fail] got $count MP_PRIO[s] RX expected $mp_prio_nr_rx"
 		fail_test
 		dump_stats=1
@@ -1819,7 +1921,7 @@ wait_attempt_fail()
 	while [ $time -lt $timeout_ms ]; do
 		local cnt
 
-		cnt=$(ip netns exec $ns nstat -as TcpAttemptFails | grep TcpAttemptFails | awk '{print $2}')
+		cnt=$(get_counter ${ns} "TcpAttemptFails")
 
 		[ "$cnt" = 1 ] && return 1
 		time=$((time + 100))
@@ -1912,23 +2014,23 @@ subflows_error_tests()
 	fi
 
 	# multiple subflows, with subflow creation error
-	if reset "multi subflows, with failing subflow"; then
+	if reset_with_tcp_filter "multi subflows, with failing subflow" ns1 10.0.3.2 REJECT &&
+	   continue_if mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
 		pm_nl_set_limits $ns1 0 2
 		pm_nl_set_limits $ns2 0 2
 		pm_nl_add_endpoint $ns2 10.0.3.2 flags subflow
 		pm_nl_add_endpoint $ns2 10.0.2.2 flags subflow
-		filter_tcp_from $ns1 10.0.3.2 REJECT
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
 		chk_join_nr 1 1 1
 	fi
 
 	# multiple subflows, with subflow timeout on MPJ
-	if reset "multi subflows, with subflow timeout"; then
+	if reset_with_tcp_filter "multi subflows, with subflow timeout" ns1 10.0.3.2 DROP &&
+	   continue_if mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
 		pm_nl_set_limits $ns1 0 2
 		pm_nl_set_limits $ns2 0 2
 		pm_nl_add_endpoint $ns2 10.0.3.2 flags subflow
 		pm_nl_add_endpoint $ns2 10.0.2.2 flags subflow
-		filter_tcp_from $ns1 10.0.3.2 DROP
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
 		chk_join_nr 1 1 1
 	fi
@@ -1936,11 +2038,11 @@ subflows_error_tests()
 	# multiple subflows, check that the endpoint corresponding to
 	# closed subflow (due to reset) is not reused if additional
 	# subflows are added later
-	if reset "multi subflows, fair usage on close"; then
+	if reset_with_tcp_filter "multi subflows, fair usage on close" ns1 10.0.3.2 REJECT &&
+	   continue_if mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_set_limits $ns2 0 1
 		pm_nl_add_endpoint $ns2 10.0.3.2 flags subflow
-		filter_tcp_from $ns1 10.0.3.2 REJECT
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow &
 
 		# mpj subflow will be in TW after the reset
@@ -2040,11 +2142,18 @@ signal_address_tests()
 		# the peer could possibly miss some addr notification, allow retransmission
 		ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=1
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
-		chk_join_nr 3 3 3
 
-		# the server will not signal the address terminating
-		# the MPC subflow
-		chk_add_nr 3 3
+		# It is not directly linked to the commit introducing this
+		# symbol but for the parent one which is linked anyway.
+		if ! mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
+			chk_join_nr 3 3 2
+			chk_add_nr 4 4
+		else
+			chk_join_nr 3 3 3
+			# the server will not signal the address terminating
+			# the MPC subflow
+			chk_add_nr 3 3
+		fi
 	fi
 }
 
@@ -2285,7 +2394,12 @@ remove_tests()
 		pm_nl_add_endpoint $ns2 10.0.4.2 flags subflow
 		run_tests $ns1 $ns2 10.0.1.1 0 -8 -8 slow
 		chk_join_nr 3 3 3
-		chk_rm_nr 0 3 simult
+
+		if mptcp_lib_kversion_ge 5.18; then
+			chk_rm_nr 0 3 simult
+		else
+			chk_rm_nr 3 3
+		fi
 	fi
 
 	# addresses flush
@@ -2523,7 +2637,8 @@ v4mapped_tests()
 
 mixed_tests()
 {
-	if reset "IPv4 sockets do not use IPv6 addresses"; then
+	if reset "IPv4 sockets do not use IPv6 addresses" &&
+	   continue_if mptcp_lib_kversion_ge 6.3; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_set_limits $ns2 1 1
 		pm_nl_add_endpoint $ns1 dead:beef:2::1 flags signal
@@ -2532,7 +2647,8 @@ mixed_tests()
 	fi
 
 	# Need an IPv6 mptcp socket to allow subflows of both families
-	if reset "simult IPv4 and IPv6 subflows"; then
+	if reset "simult IPv4 and IPv6 subflows" &&
+	   continue_if mptcp_lib_kversion_ge 6.3; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_set_limits $ns2 1 1
 		pm_nl_add_endpoint $ns1 10.0.1.1 flags signal
@@ -2541,7 +2657,8 @@ mixed_tests()
 	fi
 
 	# cross families subflows will not be created even in fullmesh mode
-	if reset "simult IPv4 and IPv6 subflows, fullmesh 1x1"; then
+	if reset "simult IPv4 and IPv6 subflows, fullmesh 1x1" &&
+	   continue_if mptcp_lib_kversion_ge 6.3; then
 		pm_nl_set_limits $ns1 0 4
 		pm_nl_set_limits $ns2 1 4
 		pm_nl_add_endpoint $ns2 dead:beef:2::2 flags subflow,fullmesh
@@ -2552,7 +2669,8 @@ mixed_tests()
 
 	# fullmesh still tries to create all the possibly subflows with
 	# matching family
-	if reset "simult IPv4 and IPv6 subflows, fullmesh 2x2"; then
+	if reset "simult IPv4 and IPv6 subflows, fullmesh 2x2" &&
+	   continue_if mptcp_lib_kversion_ge 6.3; then
 		pm_nl_set_limits $ns1 0 4
 		pm_nl_set_limits $ns2 2 4
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
@@ -2565,7 +2683,8 @@ mixed_tests()
 backup_tests()
 {
 	# single subflow, backup
-	if reset "single subflow, backup"; then
+	if reset "single subflow, backup" &&
+	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_set_limits $ns2 0 1
 		pm_nl_add_endpoint $ns2 10.0.3.2 flags subflow,backup
@@ -2575,7 +2694,8 @@ backup_tests()
 	fi
 
 	# single address, backup
-	if reset "single address, backup"; then
+	if reset "single address, backup" &&
+	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
 		pm_nl_set_limits $ns2 1 1
@@ -2586,7 +2706,8 @@ backup_tests()
 	fi
 
 	# single address with port, backup
-	if reset "single address with port, backup"; then
+	if reset "single address with port, backup" &&
+	   continue_if mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal port 10100
 		pm_nl_set_limits $ns2 1 1
@@ -2596,14 +2717,16 @@ backup_tests()
 		chk_prio_nr 1 1
 	fi
 
-	if reset "mpc backup"; then
+	if reset "mpc backup" &&
+	   continue_if mptcp_lib_kallsyms_doesnt_have "mptcp_subflow_send_ack$"; then
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow,backup
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
 		chk_join_nr 0 0 0
 		chk_prio_nr 0 1
 	fi
 
-	if reset "mpc backup both sides"; then
+	if reset "mpc backup both sides" &&
+	   continue_if mptcp_lib_kallsyms_doesnt_have "mptcp_subflow_send_ack$"; then
 		pm_nl_add_endpoint $ns1 10.0.1.1 flags subflow,backup
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow,backup
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
@@ -2611,14 +2734,16 @@ backup_tests()
 		chk_prio_nr 1 1
 	fi
 
-	if reset "mpc switch to backup"; then
+	if reset "mpc switch to backup" &&
+	   continue_if mptcp_lib_kallsyms_doesnt_have "mptcp_subflow_send_ack$"; then
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow backup
 		chk_join_nr 0 0 0
 		chk_prio_nr 0 1
 	fi
 
-	if reset "mpc switch to backup both sides"; then
+	if reset "mpc switch to backup both sides" &&
+	   continue_if mptcp_lib_kallsyms_doesnt_have "mptcp_subflow_send_ack$"; then
 		pm_nl_add_endpoint $ns1 10.0.1.1 flags subflow
 		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow
 		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow backup
@@ -2644,38 +2769,41 @@ verify_listener_events()
 	local family
 	local saddr
 	local sport
+	local name
 
 	if [ $e_type = $LISTENER_CREATED ]; then
-		stdbuf -o0 -e0 printf "\t\t\t\t\t CREATE_LISTENER %s:%s"\
-			$e_saddr $e_sport
+		name="LISTENER_CREATED"
 	elif [ $e_type = $LISTENER_CLOSED ]; then
-		stdbuf -o0 -e0 printf "\t\t\t\t\t CLOSE_LISTENER %s:%s "\
-			$e_saddr $e_sport
+		name="LISTENER_CLOSED"
+	else
+		name="$e_type"
 	fi
 
-	type=$(grep "type:$e_type," $evt |
-	       sed --unbuffered -n 's/.*\(type:\)\([[:digit:]]*\).*$/\2/p;q')
-	family=$(grep "type:$e_type," $evt |
-		 sed --unbuffered -n 's/.*\(family:\)\([[:digit:]]*\).*$/\2/p;q')
-	sport=$(grep "type:$e_type," $evt |
-		sed --unbuffered -n 's/.*\(sport:\)\([[:digit:]]*\).*$/\2/p;q')
+	printf "%-${nr_blank}s %s %s:%s " " " "$name" "$e_saddr" "$e_sport"
+
+	if ! mptcp_lib_kallsyms_has "mptcp_event_pm_listener$"; then
+		printf "[skip]: event not supported\n"
+		return
+	fi
+
+	type=$(grep "type:$e_type," $evt | sed -n 's/.*\(type:\)\([[:digit:]]*\).*$/\2/p;q')
+	family=$(grep "type:$e_type," $evt | sed -n 's/.*\(family:\)\([[:digit:]]*\).*$/\2/p;q')
+	sport=$(grep "type:$e_type," $evt | sed -n 's/.*\(sport:\)\([[:digit:]]*\).*$/\2/p;q')
 	if [ $family ] && [ $family = $AF_INET6 ]; then
-		saddr=$(grep "type:$e_type," $evt |
-			sed --unbuffered -n 's/.*\(saddr6:\)\([0-9a-f:.]*\).*$/\2/p;q')
+		saddr=$(grep "type:$e_type," $evt | sed -n 's/.*\(saddr6:\)\([0-9a-f:.]*\).*$/\2/p;q')
 	else
-		saddr=$(grep "type:$e_type," $evt |
-			sed --unbuffered -n 's/.*\(saddr4:\)\([0-9.]*\).*$/\2/p;q')
+		saddr=$(grep "type:$e_type," $evt | sed -n 's/.*\(saddr4:\)\([0-9.]*\).*$/\2/p;q')
 	fi
 
 	if [ $type ] && [ $type = $e_type ] &&
 	   [ $family ] && [ $family = $e_family ] &&
 	   [ $saddr ] && [ $saddr = $e_saddr ] &&
 	   [ $sport ] && [ $sport = $e_sport ]; then
-		stdbuf -o0 -e0 printf "[ ok ]\n"
+		echo "[ ok ]"
 		return 0
 	fi
 	fail_test
-	stdbuf -o0 -e0 printf "[fail]\n"
+	echo "[fail]"
 }
 
 add_addr_ports_tests()
@@ -2981,7 +3109,8 @@ fullmesh_tests()
 	fi
 
 	# set fullmesh flag
-	if reset "set fullmesh flag test"; then
+	if reset "set fullmesh flag test" &&
+	   continue_if mptcp_lib_kversion_ge 5.18; then
 		pm_nl_set_limits $ns1 4 4
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags subflow
 		pm_nl_set_limits $ns2 4 4
@@ -2991,7 +3120,8 @@ fullmesh_tests()
 	fi
 
 	# set nofullmesh flag
-	if reset "set nofullmesh flag test"; then
+	if reset "set nofullmesh flag test" &&
+	   continue_if mptcp_lib_kversion_ge 5.18; then
 		pm_nl_set_limits $ns1 4 4
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags subflow,fullmesh
 		pm_nl_set_limits $ns2 4 4
@@ -3001,7 +3131,8 @@ fullmesh_tests()
 	fi
 
 	# set backup,fullmesh flags
-	if reset "set backup,fullmesh flags test"; then
+	if reset "set backup,fullmesh flags test" &&
+	   continue_if mptcp_lib_kversion_ge 5.18; then
 		pm_nl_set_limits $ns1 4 4
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags subflow
 		pm_nl_set_limits $ns2 4 4
@@ -3012,7 +3143,8 @@ fullmesh_tests()
 	fi
 
 	# set nobackup,nofullmesh flags
-	if reset "set nobackup,nofullmesh flags test"; then
+	if reset "set nobackup,nofullmesh flags test" &&
+	   continue_if mptcp_lib_kversion_ge 5.18; then
 		pm_nl_set_limits $ns1 4 4
 		pm_nl_set_limits $ns2 4 4
 		pm_nl_add_endpoint $ns2 10.0.2.2 flags subflow,backup,fullmesh
@@ -3025,14 +3157,14 @@ fullmesh_tests()
 
 fastclose_tests()
 {
-	if reset "fastclose test"; then
+	if reset_check_counter "fastclose test" "MPTcpExtMPFastcloseTx"; then
 		run_tests $ns1 $ns2 10.0.1.1 1024 0 fastclose_client
 		chk_join_nr 0 0 0
 		chk_fclose_nr 1 1
 		chk_rst_nr 1 1 invert
 	fi
 
-	if reset "fastclose server test"; then
+	if reset_check_counter "fastclose server test" "MPTcpExtMPFastcloseRx"; then
 		run_tests $ns1 $ns2 10.0.1.1 1024 0 fastclose_server
 		chk_join_nr 0 0 0
 		chk_fclose_nr 1 1 invert
@@ -3070,7 +3202,8 @@ fail_tests()
 userspace_tests()
 {
 	# userspace pm type prevents add_addr
-	if reset "userspace pm type prevents add_addr"; then
+	if reset "userspace pm type prevents add_addr" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns1
 		pm_nl_set_limits $ns1 0 2
 		pm_nl_set_limits $ns2 0 2
@@ -3081,7 +3214,8 @@ userspace_tests()
 	fi
 
 	# userspace pm type does not echo add_addr without daemon
-	if reset "userspace pm no echo w/o daemon"; then
+	if reset "userspace pm no echo w/o daemon" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns2
 		pm_nl_set_limits $ns1 0 2
 		pm_nl_set_limits $ns2 0 2
@@ -3092,7 +3226,8 @@ userspace_tests()
 	fi
 
 	# userspace pm type rejects join
-	if reset "userspace pm type rejects join"; then
+	if reset "userspace pm type rejects join" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns1
 		pm_nl_set_limits $ns1 1 1
 		pm_nl_set_limits $ns2 1 1
@@ -3102,7 +3237,8 @@ userspace_tests()
 	fi
 
 	# userspace pm type does not send join
-	if reset "userspace pm type does not send join"; then
+	if reset "userspace pm type does not send join" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns2
 		pm_nl_set_limits $ns1 1 1
 		pm_nl_set_limits $ns2 1 1
@@ -3112,7 +3248,8 @@ userspace_tests()
 	fi
 
 	# userspace pm type prevents mp_prio
-	if reset "userspace pm type prevents mp_prio"; then
+	if reset "userspace pm type prevents mp_prio" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns1
 		pm_nl_set_limits $ns1 1 1
 		pm_nl_set_limits $ns2 1 1
@@ -3123,7 +3260,8 @@ userspace_tests()
 	fi
 
 	# userspace pm type prevents rm_addr
-	if reset "userspace pm type prevents rm_addr"; then
+	if reset "userspace pm type prevents rm_addr" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns1
 		set_userspace_pm $ns2
 		pm_nl_set_limits $ns1 0 1
@@ -3135,7 +3273,8 @@ userspace_tests()
 	fi
 
 	# userspace pm add & remove address
-	if reset_with_events "userspace pm add & remove address"; then
+	if reset_with_events "userspace pm add & remove address" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns1
 		pm_nl_set_limits $ns2 1 1
 		run_tests $ns1 $ns2 10.0.1.1 0 userspace_1 0 slow
@@ -3146,7 +3285,8 @@ userspace_tests()
 	fi
 
 	# userspace pm create destroy subflow
-	if reset_with_events "userspace pm create destroy subflow"; then
+	if reset_with_events "userspace pm create destroy subflow" &&
+	   continue_if mptcp_lib_has_file '/proc/sys/net/mptcp/pm_type'; then
 		set_userspace_pm $ns2
 		pm_nl_set_limits $ns1 0 1
 		run_tests $ns1 $ns2 10.0.1.1 0 0 userspace_1 slow
@@ -3158,8 +3298,10 @@ userspace_tests()
 
 endpoint_tests()
 {
+	# subflow_rebuild_header is needed to support the implicit flag
 	# userspace pm type prevents add_addr
-	if reset "implicit EP"; then
+	if reset "implicit EP" &&
+	   mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
 		pm_nl_set_limits $ns1 2 2
 		pm_nl_set_limits $ns2 2 2
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
@@ -3179,7 +3321,8 @@ endpoint_tests()
 		kill_tests_wait
 	fi
 
-	if reset "delete and re-add"; then
+	if reset "delete and re-add" &&
+	   mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
 		pm_nl_set_limits $ns1 1 1
 		pm_nl_set_limits $ns2 1 1
 		pm_nl_add_endpoint $ns2 10.0.2.2 id 2 dev ns2eth2 flags subflow
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index 29b65f4b73b29..f32045b23b893 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -76,3 +76,29 @@ mptcp_lib_kallsyms_doesnt_have() {
 
 	mptcp_lib_fail_if_expected_feature "${sym} symbol has been found"
 }
+
+# !!!AVOID USING THIS!!!
+# Features might not land in the expected version and features can be backported
+#
+# $1: kernel version, e.g. 6.3
+mptcp_lib_kversion_ge() {
+	local exp_maj="${1%.*}"
+	local exp_min="${1#*.}"
+	local v maj min
+
+	# If the kernel has backported features, set this env var to 1:
+	if [ "${SELFTESTS_MPTCP_LIB_NO_KVERSION_CHECK:-}" = "1" ]; then
+		return 0
+	fi
+
+	v=$(uname -r | cut -d'.' -f1,2)
+	maj=${v%.*}
+	min=${v#*.}
+
+	if   [ "${maj}" -gt "${exp_maj}" ] ||
+	   { [ "${maj}" -eq "${exp_maj}" ] && [ "${min}" -ge "${exp_min}" ]; }; then
+		return 0
+	fi
+
+	mptcp_lib_fail_if_expected_feature "kernel version ${1} lower than ${v}"
+}