Re: [PATCH v3 1/7] selftests/cgroup: skip test_zswap if zswap is globally disabled

[Yosry Ahmed <yosry@kernel.org>]

> diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c
> index 64ebc3f3f203..e69d845d3592 100644
> --- a/tools/testing/selftests/cgroup/test_zswap.c
> +++ b/tools/testing/selftests/cgroup/test_zswap.c
> @@ -589,9 +589,21 @@ struct zswap_test {
>  };
>  #undef T
>
> -static bool zswap_configured(void)
> +static void check_zswap_enabled(void)
>  {
> -       return access("/sys/module/zswap", F_OK) == 0;
> +       char value[2];

Please wait for discussions on the previous version to conclude and
give people a little bit of time to respond before sending the next
version.

I think this can just be be:

    char value;
    ...

    if (read_text(.., &value, sizeof(value)) < 0)

> +
> +       if (access("/sys/module/zswap", F_OK))
> +               ksft_exit_skip("zswap isn't configured\n");
> +
> +       if (read_text("/sys/module/zswap/parameters/enabled", value,
> +                                               sizeof(value)) <= 0)
> +               ksft_exit_fail_msg("Failed to read "
> +                               "/sys/module/zswap/parameters/enabled\n");
> +
> +       if (value[0] == 'N')
> +               ksft_exit_skip("zswap is disabled (hint: echo 1 > "
> +                               "/sys/module/zswap/parameters/enabled)\n");
>  }
>
>  int main(int argc, char **argv)
> @@ -604,8 +616,7 @@ int main(int argc, char **argv)
>         if (cg_find_unified_root(root, sizeof(root), NULL))
>                 ksft_exit_skip("cgroup v2 isn't mounted\n");
>
> -       if (!zswap_configured())
> -               ksft_exit_skip("zswap isn't configured\n");
> +       check_zswap_enabled();
>
>         /*
>          * Check that memory controller is available:
> --
> 2.53.0
>
>