Re: [PATCH v4] mm/page_alloc: simplify page_is_buddy() for better code readability

[Pankaj Gupta <pankaj.gupta.linux@gmail.com>]

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> Simplify page_is_buddy() to reduce the redundant code for better code
> readability.
>
> Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
> ---
> changes in v4:
>  - change the return type of page_is_buddy() from int to bool.
>  - reflow the comment into fewer lines.
> ---
>  mm/page_alloc.c | 33 +++++++++++++--------------------
>  1 file changed, 13 insertions(+), 20 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3c4eb75..229fc8c 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -791,32 +791,25 @@ static inline void set_page_order(struct page *page,
> unsigned int order)
>   *
>   * For recording page's order, we use page_private(page).
>   */
> -static inline int page_is_buddy(struct page *page, struct page *buddy,
> +static inline bool page_is_buddy(struct page *page, struct page *buddy,
>                                                         unsigned int order)
>  {
> -       if (page_is_guard(buddy) && page_order(buddy) == order) {
> -               if (page_zone_id(page) != page_zone_id(buddy))
> -                       return 0;
> -
> -               VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
> +       if (!page_is_guard(buddy) && !PageBuddy(buddy))
> +               return false;
>
> -               return 1;
> -       }
> +       if (page_order(buddy) != order)
> +               return false;
>
> -       if (PageBuddy(buddy) && page_order(buddy) == order) {
> -               /*
> -                * zone check is done late to avoid uselessly
> -                * calculating zone/node ids for pages that could
> -                * never merge.
> -                */
> -               if (page_zone_id(page) != page_zone_id(buddy))
> -                       return 0;
> +       /*
> +        * zone check is done late to avoid uselessly calculating
> +        * zone/node ids for pages that could never merge.
> +        */
> +       if (page_zone_id(page) != page_zone_id(buddy))
> +               return false;
>
> -               VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
> +       VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
>
> -               return 1;
> -       }
> -       return 0;
> +       return true;
>  }
>
>  #ifdef CONFIG_COMPACTION
> --
>

Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>


> 1.9.1
>
>

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