Merge branch 'selftests-bpf-enfoce-so_reuseaddr-in-basic-test-servers'

Alexis Lothoré says:

====================
This small series is another follow-up to [1], in which I misunderstood
Martin's initial feedback (see [2]). I proposed to make tc-tunnel apply
SO_REUSEPORT once server is brought up. This series updates
start_server_addr to really apply Martin's proposal after his
clarification [3]

[1] https://lore.kernel.org/bpf/20251031-tc_tunnel_improv-v1-0-0ffe44d27eda@bootlin.com/
[2] https://lore.kernel.org/bpf/efa3540a-1f52-46ca-9f49-e631a5e3e48c@linux.dev/
[3] https://lore.kernel.org/bpf/4cbabdf1-af2c-490a-a41a-b40c1539c1cb@linux.dev/
====================

Link: https://patch.msgid.link/20251105-start-server-soreuseaddr-v1-0-1bbd9c1f8d65@bootlin.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Author: Martin KaFai Lau

tools/testing/selftests/bpf/network_helpers.c

@@ -97,7 +97,7 @@ int settimeo(int fd, int timeout_ms)
 int start_server_addr(int type, const struct sockaddr_storage *addr, socklen_t addrlen,
 		      const struct network_helper_opts *opts)
 {
-	int fd;
+	int on = 1, fd;
 
 	if (!opts)
 		opts = &default_opts;
@@ -111,6 +111,12 @@ int start_server_addr(int type, const struct sockaddr_storage *addr, socklen_t a
 	if (settimeo(fd, opts->timeout_ms))
 		goto error_close;
 
+	if (type == SOCK_STREAM &&
+	    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))) {
+		log_err("Failed to enable SO_REUSEADDR");
+		goto error_close;
+	}
+
 	if (opts->post_socket_cb &&
 	    opts->post_socket_cb(fd, opts->cb_opts)) {
 		log_err("Failed to call post_socket_cb");

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

@@ -69,7 +69,7 @@ struct subtest_cfg {
 	int client_egress_prog_fd;
 	int server_ingress_prog_fd;
 	char extra_decap_mod_args[TUNNEL_ARGS_MAX_LEN];
-	int *server_fd;
+	int server_fd;
 };
 
 struct connection {
@@ -135,26 +135,23 @@ static int run_server(struct subtest_cfg *cfg)
 {
 	int family = cfg->ipproto == 6 ? AF_INET6 : AF_INET;
 	struct nstoken *nstoken;
+	struct network_helper_opts opts = {
+		.timeout_ms = TIMEOUT_MS
+	};
 
 	nstoken = open_netns(SERVER_NS);
 	if (!ASSERT_OK_PTR(nstoken, "open server ns"))
 		return -1;
 
-	cfg->server_fd = start_reuseport_server(family, SOCK_STREAM,
-						cfg->server_addr, TEST_PORT,
-						TIMEOUT_MS, 1);
+	cfg->server_fd = start_server_str(family, SOCK_STREAM, cfg->server_addr,
+					  TEST_PORT, &opts);
 	close_netns(nstoken);
-	if (!ASSERT_OK_PTR(cfg->server_fd, "start server"))
+	if (!ASSERT_OK_FD(cfg->server_fd, "start server"))
 		return -1;
 
 	return 0;
 }
 
-static void stop_server(struct subtest_cfg *cfg)
-{
-	free_fds(cfg->server_fd, 1);
-}
-
 static int check_server_rx_data(struct subtest_cfg *cfg,
 				struct connection *conn, int len)
 {
@@ -188,7 +185,7 @@ static struct connection *connect_client_to_server(struct subtest_cfg *cfg)
 		return NULL;
 	}
 
-	server_fd = accept(*cfg->server_fd, NULL, NULL);
+	server_fd = accept(cfg->server_fd, NULL, NULL);
 	if (server_fd < 0) {
 		close(client_fd);
 		free(conn);
@@ -384,12 +381,13 @@ static int configure_ebpf_decapsulation(struct subtest_cfg *cfg)
 
 static void run_test(struct subtest_cfg *cfg)
 {
-	struct nstoken *nstoken = open_netns(CLIENT_NS);
+	struct nstoken *nstoken;
 
-	if (!ASSERT_OK_PTR(nstoken, "open client ns"))
+	if (!ASSERT_OK(run_server(cfg), "run server"))
 		return;
 
-	if (!ASSERT_OK(run_server(cfg), "run server"))
+	nstoken = open_netns(CLIENT_NS);
+	if (!ASSERT_OK_PTR(nstoken, "open client ns"))
 		goto fail;
 
 	/* Basic communication must work */
@@ -416,8 +414,8 @@ static void run_test(struct subtest_cfg *cfg)
 	ASSERT_OK(send_and_test_data(cfg, true), "connect with encap and decap progs");
 
 fail:
-	stop_server(cfg);
 	close_netns(nstoken);
+	close(cfg->server_fd);
 }
 
 static int setup(void)