* [PATCH v3] mm/page_alloc: simplify page_is_buddy() for better code readability
@ 2020-03-10 9:15 qiwuchen55
2020-03-10 9:36 ` Vlastimil Babka
2020-03-10 12:48 ` Matthew Wilcox
0 siblings, 2 replies; 3+ messages in thread
From: qiwuchen55 @ 2020-03-10 9:15 UTC (permalink / raw)
To: akpm, vbabka, pankaj.gupta.linux, alexander.duyck, willy, bhe
Cc: linux-mm, chenqiwu
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 v3:
- exchange the first two condition statements in v2 because the page type
must be checked first.
---
mm/page_alloc.c | 32 +++++++++++++-------------------
1 file changed, 13 insertions(+), 19 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3c4eb75..412f5d5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -794,29 +794,23 @@ static inline void set_page_order(struct page *page, unsigned int order)
static inline int 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 0;
- return 1;
- }
+ if (page_order(buddy) != order)
+ return 0;
- 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 0;
- VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+ VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
- return 1;
- }
- return 0;
+ return 1;
}
#ifdef CONFIG_COMPACTION
--
1.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] mm/page_alloc: simplify page_is_buddy() for better code readability
2020-03-10 9:15 [PATCH v3] mm/page_alloc: simplify page_is_buddy() for better code readability qiwuchen55
@ 2020-03-10 9:36 ` Vlastimil Babka
2020-03-10 12:48 ` Matthew Wilcox
1 sibling, 0 replies; 3+ messages in thread
From: Vlastimil Babka @ 2020-03-10 9:36 UTC (permalink / raw)
To: qiwuchen55, akpm, pankaj.gupta.linux, alexander.duyck, willy, bhe
Cc: linux-mm, chenqiwu
On 3/10/20 10:15 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>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] mm/page_alloc: simplify page_is_buddy() for better code readability
2020-03-10 9:15 [PATCH v3] mm/page_alloc: simplify page_is_buddy() for better code readability qiwuchen55
2020-03-10 9:36 ` Vlastimil Babka
@ 2020-03-10 12:48 ` Matthew Wilcox
1 sibling, 0 replies; 3+ messages in thread
From: Matthew Wilcox @ 2020-03-10 12:48 UTC (permalink / raw)
To: qiwuchen55
Cc: akpm, vbabka, pankaj.gupta.linux, alexander.duyck, bhe, linux-mm,
chenqiwu
On Tue, Mar 10, 2020 at 05:15:29PM +0800, qiwuchen55@gmail.com wrote:
> Simplify page_is_buddy() to reduce the redundant code for better code
> readability.
If you're making these larger changes, then ...
> @@ -794,29 +794,23 @@ static inline void set_page_order(struct page *page, unsigned int order)
> static inline int page_is_buddy(struct page *page, struct page *buddy,
> unsigned int order)
Ideally this should return 'bool'.
> + /*
> + * zone check is done late to avoid uselessly
> + * calculating zone/node ids for pages that could
> + * never merge.
> + */
This comment could be reflowed onto fewer lines.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-03-10 9:36 ` Vlastimil Babka
2020-03-10 12:48 ` Matthew Wilcox
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