selftests: userspace pm: avoid relaunching pm events

'make_connection' is launched twice: once for IPv4, once for IPv6.

But then, the "pm_nl_ctl events" was launched a first time, killed, then
relaunched after for no particular reason.

We can then move this code, and the generation of the temp file to
exchange, to the init part, and remove extra conditions that no longer
needed.
Reviewed-by: Mat Martineau <martineau@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-v2-12-bc79e6e5e6a0@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -149,17 +149,23 @@ ip -net "$ns2" addr add dead:beef:1::2/64 dev ns2eth1 nodad
 ip -net "$ns2" addr add dead:beef:2::2/64 dev ns2eth1 nodad
 ip -net "$ns2" link set ns2eth1 up
 
+file=$(mktemp)
+mptcp_lib_make_file "$file" 2 1
+
+# Capture netlink events over the two network namespaces running
+# the MPTCP client and server
+client_evts=$(mktemp)
+mptcp_lib_events "${ns2}" "${client_evts}" client_evts_pid
+server_evts=$(mktemp)
+mptcp_lib_events "${ns1}" "${server_evts}" server_evts_pid
+sleep 0.5
+
 print_title "Init"
 print_test "Created network namespaces ns1, ns2"
 test_pass
 
 make_connection()
 {
-	if [ -z "$file" ]; then
-		file=$(mktemp)
-	fi
-	mptcp_lib_make_file "$file" 2 1
-
 	local is_v6=$1
 	local app_port=$app4_port
 	local connect_addr="10.0.1.1"
@@ -173,17 +179,8 @@ make_connection()
 		is_v6="v4"
 	fi
 
-	# Capture netlink events over the two network namespaces running
-	# the MPTCP client and server
-	if [ -z "$client_evts" ]; then
-		client_evts=$(mktemp)
-	fi
-	mptcp_lib_events "${ns2}" "${client_evts}" client_evts_pid
-	if [ -z "$server_evts" ]; then
-		server_evts=$(mktemp)
-	fi
-	mptcp_lib_events "${ns1}" "${server_evts}" server_evts_pid
-	sleep 0.5
+	:>"$client_evts"
+	:>"$server_evts"
 
 	# Run the server
 	ip netns exec "$ns1" \