selftests: mptcp: list sysctl data

Listing all the values linked to the MPTCP sysctl knobs was not
exercised in MPTCP test suite.

Let's do that to avoid any regressions, but also to have a kernel with a
debug kconfig verifying more assumptions. For the moment, we are not
interested by the output, only to avoid crashes and warnings.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: matttbe

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

@@ -259,6 +259,15 @@ check_mptcp_disabled()
 	mptcp_lib_ns_init disabled_ns
 
 	print_larger_title "New MPTCP socket can be blocked via sysctl"
+
+	# mainly to cover more code
+	if ! ip netns exec ${disabled_ns} sysctl net.mptcp >/dev/null; then
+		mptcp_lib_pr_fail "not able to list net.mptcp sysctl knobs"
+		mptcp_lib_result_fail "not able to list net.mptcp sysctl knobs"
+		ret=${KSFT_FAIL}
+		return 1
+	fi
+
 	# net.mptcp.enabled should be enabled by default
 	if [ "$(ip netns exec ${disabled_ns} sysctl net.mptcp.enabled | awk '{ print $3 }')" -ne 1 ]; then
 		mptcp_lib_pr_fail "net.mptcp.enabled sysctl is not 1 by default"