netdev - [PATCH bpf-next 07/10] bpf: selftests: Restore netns after each test

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Date:   Fri, 26 Jun 2020 10:55:45 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     <bpf@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Eric Dumazet <edumazet@...gle.com>, <kernel-team@...com>,
        Lawrence Brakmo <brakmo@...com>,
        Neal Cardwell <ncardwell@...gle.com>, <netdev@...r.kernel.org>,
        Yuchung Cheng <ycheng@...gle.com>
Subject: [PATCH bpf-next 07/10] bpf: selftests: Restore netns after each test

It is common for networking tests creating its netns and making its own
setting under this new netns (e.g. changing tcp sysctl).  If the test
forgot to restore to the original netns, it would affect the
result of other tests.

This patch saves the original netns at the beginning and then restores it
after every test.  Since the restore "setns()" is not expensive, it does it
on all tests without tracking if a test has created a new netns or not.

Signed-off-by: Martin KaFai Lau <kafai@...com>
---
 tools/testing/selftests/bpf/test_progs.c | 21 +++++++++++++++++++++
 tools/testing/selftests/bpf/test_progs.h |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 54fa5fa688ce..b521ce366381 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -121,6 +121,24 @@ static void reset_affinity() {
 	}
 }
 
+static void save_netns(void)
+{
+	env.saved_netns_fd = open("/proc/self/ns/net", O_RDONLY);
+	if (env.saved_netns_fd == -1) {
+		perror("open(/proc/self/ns/net)");
+		exit(-1);
+	}
+}
+
+static void restore_netns(void)
+{
+	if (setns(env.saved_netns_fd, CLONE_NEWNET) == -1) {
+		stdio_restore();
+		perror("setns(CLONE_NEWNS)");
+		exit(-1);
+	}
+}
+
 void test__end_subtest()
 {
 	struct prog_test_def *test = env.test;
@@ -643,6 +661,7 @@ int main(int argc, char **argv)
 		return -1;
 	}
 
+	save_netns();
 	stdio_hijack();
 	for (i = 0; i < prog_test_cnt; i++) {
 		struct prog_test_def *test = &prog_test_defs[i];
@@ -673,6 +692,7 @@ int main(int argc, char **argv)
 			test->error_cnt ? "FAIL" : "OK");
 
 		reset_affinity();
+		restore_netns();
 		if (test->need_cgroup_cleanup)
 			cleanup_cgroup_environment();
 	}
@@ -686,6 +706,7 @@ int main(int argc, char **argv)
 	free_str_set(&env.subtest_selector.blacklist);
 	free_str_set(&env.subtest_selector.whitelist);
 	free(env.subtest_selector.num_set);
+	close(env.saved_netns_fd);
 
 	return env.fail_cnt ? EXIT_FAILURE : EXIT_SUCCESS;
 }
diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index f4503c926aca..b80924603918 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -78,6 +78,8 @@ struct test_env {
 	int sub_succ_cnt; /* successful sub-tests */
 	int fail_cnt; /* total failed tests + sub-tests */
 	int skip_cnt; /* skipped tests */
+
+	int saved_netns_fd;
 };
 
 extern struct test_env env;
-- 
2.24.1