On Thu, Jul 17, 2025 at 12:49 PM Amery Hung <ameryhung@xxxxxxxxx> wrote:
>
> Test thread-safety of tld_create_key(). Since tld_create_key() does
> not rely on locks but memory barriers and atomic operations to protect
> the shared metadata, the thread-safety of the function is non-trivial.
> Make sure concurrent tld_key_create(), both valid and invalid, can not
> race and corrupt metatada, which may leads to TLDs not being thread-
> specific or duplicate TLDs with the same name.
>
> Signed-off-by: Amery Hung <ameryhung@xxxxxxxxx>
Reviewed-by: Emil Tsalapatis <emil@xxxxxxxxxxxxxxx>
> ---
> .../bpf/prog_tests/test_task_local_data.c | 105 ++++++++++++++++++
> 1 file changed, 105 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/test_task_local_data.c b/tools/testing/selftests/bpf/prog_tests/test_task_local_data.c
> index fde4a030ab42..1d3ccb98b5db 100644
> --- a/tools/testing/selftests/bpf/prog_tests/test_task_local_data.c
> +++ b/tools/testing/selftests/bpf/prog_tests/test_task_local_data.c
> @@ -185,8 +185,113 @@ static void test_task_local_data_basic(void)
> test_task_local_data__destroy(skel);
> }
>
> +#define TEST_RACE_THREAD_NUM (TLD_MAX_DATA_CNT - 3)
> +
> +void *test_task_local_data_race_thread(void *arg)
> +{
> + int err = 0, id = (intptr_t)arg;
> + char key_name[32];
> + tld_key_t key;
> +
> + key = tld_create_key("value_not_exist", TLD_PAGE_SIZE + 1);
> + if (tld_key_err_or_zero(key) != -E2BIG) {
> + err = 1;
> + goto out;
> + }
> +
> + /* Only one thread will succeed in creating value1 */
> + key = tld_create_key("value1", sizeof(int));
> + if (!tld_key_is_err(key))
> + tld_keys[1] = key;
> +
> + /* Only one thread will succeed in creating value2 */
> + key = tld_create_key("value2", sizeof(struct test_tld_struct));
> + if (!tld_key_is_err(key))
> + tld_keys[2] = key;
> +
> + snprintf(key_name, 32, "thread_%d", id);
> + tld_keys[id] = tld_create_key(key_name, sizeof(int));
> + if (tld_key_is_err(tld_keys[id]))
> + err = 2;
> +out:
> + return (void *)(intptr_t)err;
> +}
> +
> +static void test_task_local_data_race(void)
> +{
> + LIBBPF_OPTS(bpf_test_run_opts, opts);
> + pthread_t thread[TEST_RACE_THREAD_NUM];
> + struct test_task_local_data *skel;
> + int fd, i, j, err, *data;
> + void *ret = NULL;
> +
> + skel = test_task_local_data__open_and_load();
> + if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
> + return;
> +
> + tld_keys = calloc(TLD_MAX_DATA_CNT, sizeof(tld_key_t));
> + if (!ASSERT_OK_PTR(tld_keys, "calloc tld_keys"))
> + goto out;
> +
> + fd = bpf_map__fd(skel->maps.tld_data_map);
> +
> + ASSERT_FALSE(tld_key_is_err(value0_key), "TLD_DEFINE_KEY");
> + tld_keys[0] = value0_key;
> +
> + for (j = 0; j < 100; j++) {
> + reset_tld();
> +
> + for (i = 0; i < TEST_RACE_THREAD_NUM; i++) {
> + /*
> + * Try to make tld_create_key() race with each other. Call
> + * tld_create_key(), both valid and invalid, from different threads.
> + */
> + err = pthread_create(&thread[i], NULL, test_task_local_data_race_thread,
> + (void *)(intptr_t)(i + 3));
> + if (CHECK_FAIL(err))
> + break;
> + }
> +
> + /* Wait for all tld_create_key() to return */
> + for (i = 0; i < TEST_RACE_THREAD_NUM; i++) {
> + pthread_join(thread[i], &ret);
> + if (CHECK_FAIL(ret))
> + break;
> + }
> +
> + /* Write a unique number to each TLD */
> + for (i = 0; i < TLD_MAX_DATA_CNT; i++) {
> + data = tld_get_data(fd, tld_keys[i]);
> + if (CHECK_FAIL(!data))
> + break;
> + *data = i;
> + }
> +
> + /* Read TLDs and check the value to see if any address collides with another */
> + for (i = 0; i < TLD_MAX_DATA_CNT; i++) {
> + data = tld_get_data(fd, tld_keys[i]);
> + if (CHECK_FAIL(*data != i))
> + break;
> + }
> +
> + /* Run task_main to make sure no invalid TLDs are added */
> + err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.task_main), &opts);
> + ASSERT_OK(err, "run task_main");
> + ASSERT_OK(opts.retval, "task_main retval");
> + }
> +out:
> + if (tld_keys) {
> + free(tld_keys);
> + tld_keys = NULL;
> + }
> + tld_free();
> + test_task_local_data__destroy(skel);
> +}
> +
> void test_task_local_data(void)
> {
> if (test__start_subtest("task_local_data_basic"))
> test_task_local_data_basic();
> + if (test__start_subtest("task_local_data_race"))
> + test_task_local_data_race();
> }
> --
> 2.47.1
>
>
