linux-kernel - Re: [PATCH] fs/proc/page: Refactoring to reduce code duplication.

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Message-ID: <4a336393-6cf3-4053-8137-c6d724c3cb5f@redhat.com>
Date: Mon, 17 Mar 2025 10:18:28 +0100
From: David Hildenbrand <david@...hat.com>
To: Liu Ye <liuyerd@....com>, akpm@...ux-foundation.org
Cc: willy@...radead.org, ran.xiaokai@....com.cn, dan.carpenter@...aro.org,
 linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
 Liu Ye <liuye@...inos.cn>
Subject: Re: [PATCH] fs/proc/page: Refactoring to reduce code duplication.

On 17.03.25 10:13, Liu Ye wrote:
> 
> 在 2025/3/17 16:56, David Hildenbrand 写道:
>> On 17.03.25 09:01, Liu Ye wrote:
>>> From: Liu Ye <liuye@...inos.cn>
>>>
>>> The function kpageflags_read and kpagecgroup_read is quite similar
>>> to kpagecount_read. Consider refactoring common code into a helper
>>> function to reduce code duplication.
>>>
>>> Signed-off-by: Liu Ye <liuye@...inos.cn>
>>> ---
>>>    fs/proc/page.c | 158 ++++++++++++++++---------------------------------
>>>    1 file changed, 50 insertions(+), 108 deletions(-)
>>>
>>> diff --git a/fs/proc/page.c b/fs/proc/page.c
>>> index a55f5acefa97..f413016ebe67 100644
>>> --- a/fs/proc/page.c
>>> +++ b/fs/proc/page.c
>>> @@ -37,19 +37,17 @@ static inline unsigned long get_max_dump_pfn(void)
>>>    #endif
>>>    }
>>>    -/* /proc/kpagecount - an array exposing page mapcounts
>>> - *
>>> - * Each entry is a u64 representing the corresponding
>>> - * physical page mapcount.
>>> - */
>>> -static ssize_t kpagecount_read(struct file *file, char __user *buf,
>>> -                 size_t count, loff_t *ppos)
>>> +static ssize_t kpage_read(struct file *file, char __user *buf,
>>> +        size_t count, loff_t *ppos,
>>> +        u64 (*get_page_info)(struct page *))
>>
>> Can we just indicate using an enum which operation to perform, so we can avoid having+passing these functions?
>>
> Like this? Good idea, I'll send a new patch later.
> 
> enum kpage_operation {
>      KPAGE_FLAGS,
>      KPAGE_COUNT,
>      KPAGE_CGROUP,
> };
> 
> static u64 get_page_info(struct page *page, enum kpage_operation op)
> {
>      switch (op) {
>      case KPAGE_FLAGS:
>          return stable_page_flags(page);
>      case KPAGE_COUNT:
>          return page_count(page);
>      case KPAGE_CGROUP:
>          return page_cgroup_ino(page);
>      default:
>          return 0;
>      }
> }


Likely it's best to inline get_page_info() into kpage_read() to just get 
rid of it.


-- 
Cheers,

David / dhildenb