linux-kernel - Re: [RFC PATCH v1 32/50] lib/test*.c: Use prandom_u32

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Date:   Sat, 28 Mar 2020 21:05:15 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     George Spelvin <lkml@....org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ferdinand Blomqvist <ferdinand.blomqvist@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [RFC PATCH v1 32/50] lib/test*.c: Use prandom_u32_max()

On Sat, Mar 28, 2020 at 6:47 PM George Spelvin <lkml@....org> wrote:
>
> lib/reed_solomon/test_rslib.c alreasy uses prandom_u32();
> lib/test_hexdump.c and lib/test-string_helpers.c were using
> get_random_int() % range, which is needlessly expensive for
> test code.
>

Fine with me, FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: George Spelvin <lkml@....org>
> Cc: Ferdinand Blomqvist <ferdinand.blomqvist@...il.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  lib/reed_solomon/test_rslib.c |  4 ++--
>  lib/test-string_helpers.c     |  2 +-
>  lib/test_hexdump.c            | 10 +++++-----
>  3 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/lib/reed_solomon/test_rslib.c b/lib/reed_solomon/test_rslib.c
> index 4eb29f365ece0..58e767c142ef8 100644
> --- a/lib/reed_solomon/test_rslib.c
> +++ b/lib/reed_solomon/test_rslib.c
> @@ -183,7 +183,7 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
>
>                 do {
>                         /* Must not choose the same location twice */
> -                       errloc = prandom_u32() % len;
> +                       errloc = prandom_u32_max(len);
>                 } while (errlocs[errloc] != 0);
>
>                 errlocs[errloc] = 1;
> @@ -194,7 +194,7 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
>         for (i = 0; i < eras; i++) {
>                 do {
>                         /* Must not choose the same location twice */
> -                       errloc = prandom_u32() % len;
> +                       errloc = prandom_u32_max(len);
>                 } while (errlocs[errloc] != 0);
>
>                 derrlocs[i] = errloc;
> diff --git a/lib/test-string_helpers.c b/lib/test-string_helpers.c
> index 25b5cbfb7615b..3349f3ddc528c 100644
> --- a/lib/test-string_helpers.c
> +++ b/lib/test-string_helpers.c
> @@ -398,7 +398,7 @@ static int __init test_string_helpers_init(void)
>         for (i = 0; i < UNESCAPE_ANY + 1; i++)
>                 test_string_unescape("unescape", i, false);
>         test_string_unescape("unescape inplace",
> -                            get_random_int() % (UNESCAPE_ANY + 1), true);
> +                            prandom_u32_max(UNESCAPE_ANY + 1), true);
>
>         /* Without dictionary */
>         for (i = 0; i < (ESCAPE_ANY_NP | ESCAPE_HEX) + 1; i++)
> diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c
> index 5144899d3c6b8..54e4efb28b974 100644
> --- a/lib/test_hexdump.c
> +++ b/lib/test_hexdump.c
> @@ -149,7 +149,7 @@ static void __init test_hexdump(size_t len, int rowsize, int groupsize,
>  static void __init test_hexdump_set(int rowsize, bool ascii)
>  {
>         size_t d = min_t(size_t, sizeof(data_b), rowsize);
> -       size_t len = get_random_int() % d + 1;
> +       size_t len = prandom_u32_max(d) + 1;
>
>         test_hexdump(len, rowsize, 4, ascii);
>         test_hexdump(len, rowsize, 2, ascii);
> @@ -208,11 +208,11 @@ static void __init test_hexdump_overflow(size_t buflen, size_t len,
>  static void __init test_hexdump_overflow_set(size_t buflen, bool ascii)
>  {
>         unsigned int i = 0;
> -       int rs = (get_random_int() % 2 + 1) * 16;
> +       int rs = (prandom_u32() % 2 + 1) * 16;
>
>         do {
>                 int gs = 1 << i;
> -               size_t len = get_random_int() % rs + gs;
> +               size_t len = prandom_u32_max(rs) + gs;
>
>                 test_hexdump_overflow(buflen, rounddown(len, gs), rs, gs, ascii);
>         } while (i++ < 3);
> @@ -223,11 +223,11 @@ static int __init test_hexdump_init(void)
>         unsigned int i;
>         int rowsize;
>
> -       rowsize = (get_random_int() % 2 + 1) * 16;
> +       rowsize = (prandom_u32() % 2 + 1) * 16;
>         for (i = 0; i < 16; i++)
>                 test_hexdump_set(rowsize, false);
>
> -       rowsize = (get_random_int() % 2 + 1) * 16;
> +       rowsize = (prandom_u32() % 2 + 1) * 16;
>         for (i = 0; i < 16; i++)
>                 test_hexdump_set(rowsize, true);
>
> --
> 2.26.0
>


-- 
With Best Regards,
Andy Shevchenko