selftests/net: udpgso_bench_rx: fix port argument

The below commit added optional support for passing a bind address.
It configures the sockaddr bind arguments before parsing options and
reconfigures on options -b and -4.

This broke support for passing port (-p) on its own.

Configure sockaddr after parsing all arguments.

Fixes: 3327a9c4 ("selftests: add functionals test for UDP GRO")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/udpgso_bench_rx.c

@@ -293,19 +293,17 @@ static void usage(const char *filepath)
 
 static void parse_opts(int argc, char **argv)
 {
+	const char *bind_addr = NULL;
 	int c;
 
-	/* bind to any by default */
-	setup_sockaddr(PF_INET6, "::", &cfg_bind_addr);
 	while ((c = getopt(argc, argv, "4b:C:Gl:n:p:rR:S:tv")) != -1) {
 		switch (c) {
 		case '4':
 			cfg_family = PF_INET;
 			cfg_alen = sizeof(struct sockaddr_in);
-			setup_sockaddr(PF_INET, "0.0.0.0", &cfg_bind_addr);
 			break;
 		case 'b':
-			setup_sockaddr(cfg_family, optarg, &cfg_bind_addr);
+			bind_addr = optarg;
 			break;
 		case 'C':
 			cfg_connect_timeout_ms = strtoul(optarg, NULL, 0);
@@ -341,6 +339,11 @@ static void parse_opts(int argc, char **argv)
 		}
 	}
 
+	if (!bind_addr)
+		bind_addr = cfg_family == PF_INET6 ? "::" : "0.0.0.0";
+
+	setup_sockaddr(cfg_family, bind_addr, &cfg_bind_addr);
+
 	if (optind != argc)
 		usage(argv[0]);