linux-kernel - Re: [PATCH] mm/pgtable: Move extern zero_pfn outside __HAVE_COLOR_ZERO

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Date:   Tue, 16 Jun 2020 12:04:51 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org
Cc:     Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/pgtable: Move extern zero_pfn outside
 __HAVE_COLOR_ZERO_PAGE

On 16.06.20 11:48, Anshuman Khandual wrote:
> 
> 
> On 06/16/2020 01:09 PM, David Hildenbrand wrote:
>> On 16.06.20 06:08, Anshuman Khandual wrote:
>>> zero_pfn variable is required whether __HAVE_COLOR_ZERO_PAGE is enabled
>>
>> Why is that relevant for this patch?
> 
> That just states how it is organized right now wrt __HAVE_COLOR_ZERO_PAGE.
> 
>>
>>> or not. Also it should not really be declared individually in all functions
>>> where it gets used. Just move the declaration outside, which also makes it
>>> available for other potential users.
>>
>> So, all you're essentially doing is exposing zero_pfn in pgtable.h now.
> 
> Right, but it just happens in the process of consolidating three different
> instances of 'extern unsigned long zero_pfn' in the same file which are
> redundant.
> 
>>
>> If everybody should just use my_zero_pfn(), I don't really see the
>> benefit of this patch, sorry.
> 
> It consolidates redundant declarations and reduces code. We could just have
> a comment for zero_pfn stating that it should not be used directly.
> 

... or just leave it as is and have self-documenting code.

-- 
Thanks,

David / dhildenb