linux-kernel - Re: [PATCH] x86 : omit duplicate processing at pte

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Date:	Sun, 16 Aug 2009 11:01:22 +0900 (JST)
From:	ohyama_sec@...el-networks.com
To:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86 : omit duplicate processing at pte_pgprot()

Thank you for your genial response, and I'm sorry that I neglected to read Documentation/SubmittingPatches carefully.
And I understood DCO.

>> I suggest following PATCH that omit duplicate processing of mask.
>>
>> pte_pgprot() macro [arch/x86/include/asm/pgtable.h] call pte_flags() [arch/x86/include/asm/pgtable_types.h] that return value is masked by PTE_FLAGS_MASK in pte_flags() function, and this macro also masks the returned value by PTE_FLAGS_MASK.
>> 
>
>It probably won't make any difference in practice, because gcc will do a
>common subexpression elimination for the "& PTE_FLAGS_MASK" between the
>inline function and its caller.  But it does tidy things up a bit.
>
>> I guess that we don't have to do the mask processing at pte_pgprot() macro because it has already been masked at pte_flags().
>> So, how about the following PATCH ?
>>
>> 	<Hiroyasu OHYAMA>
>> 
>
>Please add a proper Signed-off-by: line.
>
>Acked-by: Jeremy Fitzhardinge <jeremy@...p.org>
>
>J

Signed-off-by : Hiroyasu OHYAMA <hiroyasu.ohyama@...il.com>

>> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
>> index 3cc06e3..a0b454c 100644
>> --- a/arch/x86/include/asm/pgtable.h
>> +++ b/arch/x86/include/asm/pgtable.h
>> @@ -265,7 +265,7 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
>>         return __pgprot(preservebits | addbits);
>>          }
>>
>>          -#define pte_pgprot(x) __pgprot(pte_flags(x) & PTE_FLAGS_MASK)
>>          +#define pte_pgprot(x) __pgprot(pte_flags(x))
>>
>>           #define canon_pgprot(p) __pgprot(massage_pgprot(p))
>> --
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>> 
>
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