linux-kernel - Re: [PATCH v2 3/4] kstrtox: add unit tests for memparse

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Date: Tue, 2 Jan 2024 14:23:20 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Qu Wenruo <wqu@...e.com>
Cc: linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	akpm@...ux-foundation.org, christophe.jaillet@...adoo.fr, 
	andriy.shevchenko@...ux.intel.com, David.Laight@...lab.com, ddiss@...e.de
Subject: Re: [PATCH v2 3/4] kstrtox: add unit tests for memparse_safe()

Hi Qu,

On Tue, Jan 2, 2024 at 5:13 AM Qu Wenruo <wqu@...e.com> wrote:
> The new tests cases for memparse_safe() include:
>
> - The existing test cases for kstrtoull()
>   Including all the 3 bases (8, 10, 16), and all the ok and failure
>   cases.
>   Although there are something we need to verify specific for
>   memparse_safe():
>
>   * @retptr and @value are not modified for failure cases
>
>   * return value are correct for failure cases
>
>   * @retptr is correct for the good cases
>
> - New test cases
>   Not only testing the result value, but also the @retptr, including:
>
>   * good cases with extra tailing chars, but without valid prefix
>     The @retptr should point to the first char after a valid string.
>     3 cases for all the 3 bases.
>
>   * good cases with extra tailing chars, with valid prefix
>     5 cases for all the suffixes.
>
>   * bad cases without any number but stray suffix
>     Should be rejected with -EINVAL
>
> Signed-off-by: Qu Wenruo <wqu@...e.com>

Thanks for your patch!

> --- a/lib/test-kstrtox.c
> +++ b/lib/test-kstrtox.c
> @@ -268,6 +268,237 @@ static void __init test_kstrtoll_ok(void)
>         TEST_OK(kstrtoll, long long, "%lld", test_ll_ok);
>  }
>
> +/*
> + * The special pattern to make sure the result is not modified for error cases.
> + */
> +#define ULL_PATTERN            (0xefefefef7a7a7a7aULL)
> +#if BITS_PER_LONG == 32
> +#define POINTER_PATTERN                (0xefef7a7a7aUL)

This pattern needs 40 bits to fit, so it doesn't fit in a 32-bit
unsigned long or pointer.  Probably you wanted to use 0xef7a7a7aUL
instead?

> +#else
> +#define POINTER_PATTERN                (ULL_PATTERN)
> +#endif

Shouldn't a simple cast to uintptr_t work fine for both 32-bit and
64-bit systems:

    #define POINTER_PATTERN  ((uintptr_t)ULL_PATTERN)

Or even better, incorporate the cast to a pointer:

    #define POINTER_PATTERN  ((void *)(uintptr_t)ULL_PATTERN)

so you can drop the extra cast when assigning/comparing retptr below.

> +
> +/* Want to include "E" suffix for full coverage. */
> +#define MEMPARSE_TEST_SUFFIX   (MEMPARSE_SUFFIX_K | MEMPARSE_SUFFIX_M |\
> +                                MEMPARSE_SUFFIX_G | MEMPARSE_SUFFIX_T |\
> +                                MEMPARSE_SUFFIX_P | MEMPARSE_SUFFIX_E)
> +
> +static void __init test_memparse_safe_fail(void)
> +{

[...]

> +       for_each_test(i, tests) {
> +               const struct memparse_test_fail *t = &tests[i];
> +               unsigned long long tmp = ULL_PATTERN;
> +               char *retptr = (char *)POINTER_PATTERN;
> +               int ret;

[...]

+               if (retptr != (char *)POINTER_PATTERN)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds