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    Subject[PATCH 5.8 132/232] bpf: selftests: Restore netns after each test
    Date
    From: Martin KaFai Lau <kafai@fb.com>

    [ Upstream commit 811d7e375d08312dba23f3b6bf7e58ec14aa5dcb ]

    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.

    The new restore_netns() could also be done in test__end_subtest() such
    that each subtest will get an automatic netns reset. However,
    the individual test would lose flexibility to have total control
    on netns for its own subtests. In some cases, forcing a test to do
    unnecessary netns re-configure for each subtest is time consuming.
    e.g. In my vm, forcing netns re-configure on each subtest in sk_assign.c
    increased the runtime from 1s to 8s. On top of that, test_progs.c
    is also doing per-test (instead of per-subtest) cleanup for cgroup.
    Thus, this patch also does per-test restore_netns(). The only existing
    per-subtest cleanup is reset_affinity() and no test is depending on this.
    Thus, it is removed from test__end_subtest() to give a consistent
    expectation to the individual tests. test_progs.c only ensures
    any affinity/netns/cgroup change made by an earlier test does not
    affect the following tests.

    Signed-off-by: Martin KaFai Lau <kafai@fb.com>
    Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
    Acked-by: Andrii Nakryiko <andriin@fb.com>
    Link: https://lore.kernel.org/bpf/20200702004858.2103728-1-kafai@fb.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/testing/selftests/bpf/test_progs.c | 23 +++++++++++++++++++++--
    tools/testing/selftests/bpf/test_progs.h | 2 ++
    2 files changed, 23 insertions(+), 2 deletions(-)

    diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
    index da70a4f72f547..6218b2b5a3f62 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;
    @@ -138,8 +156,6 @@ void test__end_subtest()
    test->test_num, test->subtest_num,
    test->subtest_name, sub_error_cnt ? "FAIL" : "OK");

    - reset_affinity();
    -
    free(test->subtest_name);
    test->subtest_name = NULL;
    }
    @@ -643,6 +659,7 @@ 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 +690,7 @@ 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 +704,7 @@ 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);

    if (env.succ_cnt + env.fail_cnt + env.skip_cnt == 0)
    return EXIT_FAILURE;
    diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
    index f4503c926acad..b809246039181 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;
    --
    2.25.1


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