selftests/bpf: Monitor traffic for select_reuseport.

Enable traffic monitoring for the subtests of select_reuseport.
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240815053254.470944-7-thinker.li@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

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

@@ -37,9 +37,7 @@ static int sk_fds[REUSEPORT_ARRAY_SIZE];
 static int reuseport_array = -1, outer_map = -1;
 static enum bpf_map_type inner_map_type;
 static int select_by_skb_data_prog;
-static int saved_tcp_syncookie = -1;
 static struct bpf_object *obj;
-static int saved_tcp_fo = -1;
 static __u32 index_zero;
 static int epfd;
 
@@ -193,14 +191,6 @@ static int write_int_sysctl(const char *sysctl, int v)
 	return 0;
 }
 
-static void restore_sysctls(void)
-{
-	if (saved_tcp_fo != -1)
-		write_int_sysctl(TCP_FO_SYSCTL, saved_tcp_fo);
-	if (saved_tcp_syncookie != -1)
-		write_int_sysctl(TCP_SYNCOOKIE_SYSCTL, saved_tcp_syncookie);
-}
-
 static int enable_fastopen(void)
 {
 	int fo;
@@ -793,6 +783,7 @@ static void test_config(int sotype, sa_family_t family, bool inany)
 		TEST_INIT(test_pass_on_err),
 		TEST_INIT(test_detach_bpf),
 	};
+	struct netns_obj *netns;
 	char s[MAX_TEST_NAME];
 	const struct test *t;
 
@@ -808,9 +799,21 @@ static void test_config(int sotype, sa_family_t family, bool inany)
 		if (!test__start_subtest(s))
 			continue;
 
+		netns = netns_new("select_reuseport", true);
+		if (!ASSERT_OK_PTR(netns, "netns_new"))
+			continue;
+
+		if (CHECK_FAIL(enable_fastopen()))
+			goto out;
+		if (CHECK_FAIL(disable_syncookie()))
+			goto out;
+
 		setup_per_test(sotype, family, inany, t->no_inner_map);
 		t->fn(sotype, family);
 		cleanup_per_test(t->no_inner_map);
+
+out:
+		netns_free(netns);
 	}
 }
 
@@ -850,21 +853,7 @@ void test_map_type(enum bpf_map_type mt)
 
 void serial_test_select_reuseport(void)
 {
-	saved_tcp_fo = read_int_sysctl(TCP_FO_SYSCTL);
-	if (saved_tcp_fo < 0)
-		goto out;
-	saved_tcp_syncookie = read_int_sysctl(TCP_SYNCOOKIE_SYSCTL);
-	if (saved_tcp_syncookie < 0)
-		goto out;
-
-	if (enable_fastopen())
-		goto out;
-	if (disable_syncookie())
-		goto out;
-
 	test_map_type(BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
 	test_map_type(BPF_MAP_TYPE_SOCKMAP);
 	test_map_type(BPF_MAP_TYPE_SOCKHASH);
-out:
-	restore_sysctls();
 }