Squash to "selftests/bpf: Add mptcp subflow subtest"

Use pm_nl_ctl when 'ip mptcp' fails.
Use SYS_NOFAIL in _ss_search() and drop 'ss -M'.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>

tools/testing/selftests/bpf/prog_tests/mptcp.c

@@ -362,7 +362,10 @@ static int endpoint_init(char *flags)
 	SYS(fail, "ip -net %s link set dev veth1 up", NS_TEST);
 	SYS(fail, "ip -net %s addr add %s/24 dev veth2", NS_TEST, ADDR_2);
 	SYS(fail, "ip -net %s link set dev veth2 up", NS_TEST);
-	SYS(fail, "ip -net %s mptcp endpoint add %s %s", NS_TEST, ADDR_2, flags);
+	if (SYS_NOFAIL("ip -net %s mptcp endpoint add %s %s", NS_TEST, ADDR_2, flags)) {
+		SYS(fail, "ip netns exec %s ./mptcp_pm_nl_ctl add %s flags %s",
+		    NS_TEST, ADDR_2, flags);
+	}
 
 	return 0;
 fail:
@@ -371,16 +374,8 @@ static int endpoint_init(char *flags)
 
 static int _ss_search(char *src, char *dst, char *port, char *keyword)
 {
-	char cmd[128];
-	int n;
-
-	n = snprintf(cmd, sizeof(cmd),
-		     "ip netns exec %s ss -Menita src %s dst %s %s %d | grep -q '%s'",
-		     NS_TEST, src, dst, port, PORT_1, keyword);
-	if (n < 0 || n >= sizeof(cmd))
-		return -1;
-
-	return system(cmd);
+	return SYS_NOFAIL("ip netns exec %s ss -enita src %s dst %s %s %d | grep -q '%s'",
+			  NS_TEST, src, dst, port, PORT_1, keyword);
 }
 
 static int ss_search(char *src, char *keyword)