On Tue, Mar 10, 2020 at 8:22 AM <qiwuchen55@xxxxxxxxx> wrote:
>
> From: chenqiwu <chenqiwu@xxxxxxxxxx>
>
> Simplify page_is_buddy() to reduce the redundant code for better code
> readability.
>
> Signed-off-by: chenqiwu <chenqiwu@xxxxxxxxxx>
> ---
> changes in v4:
> - change the return type of page_is_buddy() from int to bool.
> - reflow the comment into fewer lines.
> ---
Looks good to me.
Reviewed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
> 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
> --
> 1.9.1
>
