linux-kernel - Re: [PATCH v1] lib/generic-radix-tree: Make good use of while (level--)

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Message-ID: <CAHp75VekmW1T4nsp+wtOKbc8Xf_aUGUwxAw6PrpSpYEubxbNEQ@mail.gmail.com>
Date:   Thu, 21 Mar 2019 17:36:47 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Kent Overstreet <kent.overstreet@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] lib/generic-radix-tree: Make good use of while (level--)

On Thu, Mar 21, 2019 at 5:32 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> There is no need to split postincrement in while (level--) type of loops.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  lib/generic-radix-tree.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/lib/generic-radix-tree.c b/lib/generic-radix-tree.c
> index a7bafc413730..5a1818a0de1f 100644
> --- a/lib/generic-radix-tree.c
> +++ b/lib/generic-radix-tree.c
> @@ -59,13 +59,9 @@ void *__genradix_ptr(struct __genradix *radix, size_t offset)
>         if (ilog2(offset) >= genradix_depth_shift(level))
>                 return NULL;
>
> -       while (1) {
> +       while (level--) {
>                 if (!n)
>                         return NULL;
> -               if (!level)
> -                       break;
> -
> -               level--;

My bad, this will need an additional check. before the loop.

>
>                 n = n->children[offset >> genradix_depth_shift(level)];
>                 offset &= genradix_depth_size(level) - 1;
> @@ -157,9 +153,7 @@ void *__genradix_iter_peek(struct genradix_iter *iter,
>         if (ilog2(iter->offset) >= genradix_depth_shift(level))
>                 return NULL;
>
> -       while (level) {
> -               level--;
> -
> +       while (level--) {
>                 i = (iter->offset >> genradix_depth_shift(level)) &
>                         (GENRADIX_ARY - 1);
>
> --
> 2.20.1
>


-- 
With Best Regards,
Andy Shevchenko