selftests: mptcp: add mptcp_lib_events helper

To avoid duplicated code in different MPTCP selftests, we can add and
use helpers defined in mptcp_lib.sh.

This patch unifies "pm_nl_ctl events" related code in userspace_pm.sh
and mptcp_join.sh into a helper mptcp_lib_events(). Define it in
mptcp_lib.sh and use it in both scripts.

Note that mptcp_lib_kill_wait is now call before starting 'events' for
mptcp_join.sh as well, but that's fine: each test is started from a new
netns, so there will not be any existing pid there, and nothing is done
when mptcp_lib_kill_wait is called with 0.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240306-upstream-net-next-20240304-selftests-mptcp-shared-code-shellcheck-v2-6-bc79e6e5e6a0@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -430,12 +430,8 @@ reset_with_events()
 {
 	reset "${1}" || return 1
 
-	:> "$evts_ns1"
-	:> "$evts_ns2"
-	ip netns exec $ns1 ./pm_nl_ctl events >> "$evts_ns1" 2>&1 &
-	evts_ns1_pid=$!
-	ip netns exec $ns2 ./pm_nl_ctl events >> "$evts_ns2" 2>&1 &
-	evts_ns2_pid=$!
+	mptcp_lib_events "${ns1}" "${evts_ns1}" evts_ns1_pid
+	mptcp_lib_events "${ns2}" "${evts_ns2}" evts_ns2_pid
 }
 
 reset_with_tcp_filter()
@@ -608,7 +604,9 @@ wait_mpj()
 kill_events_pids()
 {
 	mptcp_lib_kill_wait $evts_ns1_pid
+	evts_ns1_pid=0
 	mptcp_lib_kill_wait $evts_ns2_pid
+	evts_ns2_pid=0
 }
 
 pm_nl_set_limits()

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

@@ -398,3 +398,15 @@ mptcp_lib_ns_exit() {
 		rm -f /tmp/"${netns}".{nstat,out}
 	done
 }
+
+mptcp_lib_events() {
+	local ns="${1}"
+	local evts="${2}"
+	declare -n pid="${3}"
+
+	:>"${evts}"
+
+	mptcp_lib_kill_wait "${pid:-0}"
+	ip netns exec "${ns}" ./pm_nl_ctl events >> "${evts}" 2>&1 &
+	pid=$!
+}

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

@@ -178,21 +178,11 @@ make_connection()
 	if [ -z "$client_evts" ]; then
 		client_evts=$(mktemp)
 	fi
-	:>"$client_evts"
-	if [ $client_evts_pid -ne 0 ]; then
-		mptcp_lib_kill_wait $client_evts_pid
-	fi
-	ip netns exec "$ns2" ./pm_nl_ctl events >> "$client_evts" 2>&1 &
-	client_evts_pid=$!
+	mptcp_lib_events "${ns2}" "${client_evts}" client_evts_pid
 	if [ -z "$server_evts" ]; then
 		server_evts=$(mktemp)
 	fi
-	:>"$server_evts"
-	if [ $server_evts_pid -ne 0 ]; then
-		mptcp_lib_kill_wait $server_evts_pid
-	fi
-	ip netns exec "$ns1" ./pm_nl_ctl events >> "$server_evts" 2>&1 &
-	server_evts_pid=$!
+	mptcp_lib_events "${ns1}" "${server_evts}" server_evts_pid
 	sleep 0.5
 
 	# Run the server