linux-kernel - Re: [PATCH] printf: add tests for generic FourCCs

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Message-ID: <CAJ-ks9=zN0pUAt9ELckna+3GcnDfhjF3jgiM1FHXLji9pWc2wQ@mail.gmail.com>
Date: Fri, 21 Mar 2025 10:16:49 -0400
From: Tamir Duberstein <tamird@...il.com>
To: Aditya Garg <gargaditya08@...e.com>
Cc: Kees Cook <kees@...nel.org>, Petr Mladek <pmladek@...e.com>, 
	Steven Rostedt <rostedt@...dmis.org>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Rasmus Villemoes <linux@...musvillemoes.dk>, Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] printf: add tests for generic FourCCs

On Thu, Mar 13, 2025 at 11:45 PM Aditya Garg <gargaditya08@...e.com> wrote:
>
> From: Aditya Garg <gargaditya08@...e.com>
>
> Format specifiers for printing generic 32-bit FourCCs were recently added
> to vsprintf. They are going through the DRM tree alongwith the appletbdrm
> driver. Since the printf tests are being converted to kunit, this separate
> patch for the tests should make it easier to rebase when the merge window
> opens.
>
> Link: https://lore.kernel.org/dri-devel/79FA3F41-FD7A-41D9-852B-D32606AF5EB4@live.com/T/#u
> Signed-off-by: Aditya Garg <gargaditya08@...e.com>
> ---
>  lib/tests/printf_kunit.c | 39 ++++++++++++++++++++++++++++++++-------
>  1 file changed, 32 insertions(+), 7 deletions(-)
>
> diff --git a/lib/tests/printf_kunit.c b/lib/tests/printf_kunit.c
> index 2c9f6170b..b1fa0dcea 100644
> --- a/lib/tests/printf_kunit.c
> +++ b/lib/tests/printf_kunit.c
> @@ -701,21 +701,46 @@ static void fwnode_pointer(struct kunit *kunittest)
>         software_node_unregister_node_group(group);
>  }
>
> +struct fourcc_struct {
> +       u32 code;
> +       const char *str;
> +};
> +
> +static void fourcc_pointer_test(struct kunit *kunittest, const struct fourcc_struct *fc,
> +                               size_t n, const char *fmt)
> +{
> +       size_t i;
> +
> +       for (i = 0; i < n; i++)
> +               test(fc[i].str, fmt, &fc[i].code);
> +}
> +
>  static void fourcc_pointer(struct kunit *kunittest)
>  {
> -       struct {
> -               u32 code;
> -               char *str;
> -       } const try[] = {
> +       static const struct fourcc_struct try_cc[] = {
>                 { 0x3231564e, "NV12 little-endian (0x3231564e)", },
>                 { 0xb231564e, "NV12 big-endian (0xb231564e)", },
>                 { 0x10111213, ".... little-endian (0x10111213)", },
>                 { 0x20303159, "Y10  little-endian (0x20303159)", },
>         };
> -       unsigned int i;
> +       static const struct fourcc_struct try_ch[] = {
> +               { 0x41424344, "ABCD (0x41424344)", },
> +       };
> +       static const struct fourcc_struct try_cn[] = {
> +               { 0x41424344, "DCBA (0x44434241)", },
> +       };
> +       static const struct fourcc_struct try_cl[] = {
> +               { (__force u32)cpu_to_le32(0x41424344), "ABCD (0x41424344)", },
> +       };
> +       static const struct fourcc_struct try_cb[] = {
> +               { (__force u32)cpu_to_be32(0x41424344), "ABCD (0x41424344)", },
> +       };
>
> -       for (i = 0; i < ARRAY_SIZE(try); i++)
> -               test(try[i].str, "%p4cc", &try[i].code);
> +       fourcc_pointer_test(kunittest, try_cc, ARRAY_SIZE(try_cc), "%p4cc");
> +       fourcc_pointer_test(kunittest, try_ch, ARRAY_SIZE(try_ch), "%p4ch");
> +       fourcc_pointer_test(kunittest, try_cn, ARRAY_SIZE(try_cn), "%p4cn");
> +       fourcc_pointer_test(kunittest, try_cl, ARRAY_SIZE(try_cl), "%p4cl");
> +       fourcc_pointer_test(kunittest, try_cb, ARRAY_SIZE(try_cb), "%p4cb");
>  }
>
>  static void
> --
> 2.43.0
>

This code looks fine to me. I would appreciate a preview of the output
of these tests when they fail; a lot of effort went into making the
printf tests produce actionable failure messages, and we should
continue to invest in that IMO.