diff mbox series

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

Message ID 1583853751-5525-1-git-send-email-qiwuchen55@gmail.com (mailing list archive)
State New, archived
Headers show
Series [v4] mm/page_alloc: simplify page_is_buddy() for better code readability | expand

Commit Message

chenqiwu March 10, 2020, 3:22 p.m. UTC
From: chenqiwu <chenqiwu@xiaomi.com>

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(-)

Comments

Alexander Duyck March 10, 2020, 3:55 p.m. UTC | #1
On Tue, Mar 10, 2020 at 8:22 AM <qiwuchen55@gmail.com> wrote:
>
> From: chenqiwu <chenqiwu@xiaomi.com>
>
> 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.
> ---

Looks good to me.

Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>

>  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
>
Matthew Wilcox March 10, 2020, 6:09 p.m. UTC | #2
On Tue, Mar 10, 2020 at 11:22:31PM +0800, qiwuchen55@gmail.com wrote:
> From: chenqiwu <chenqiwu@xiaomi.com>
> 
> Simplify page_is_buddy() to reduce the redundant code for better code
> readability.
> 
> Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Vlastimil Babka March 10, 2020, 6:23 p.m. UTC | #3
On 3/10/20 4:22 PM, qiwuchen55@gmail.com wrote:
> From: chenqiwu <chenqiwu@xiaomi.com>
> 
> Simplify page_is_buddy() to reduce the redundant code for better code
> readability.
> 
> Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

Thanks.
Pankaj Gupta March 10, 2020, 7:09 p.m. UTC | #4
> 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
>
>
diff mbox series

Patch

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