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Re: [PATCH] kernel.h: add IS_PTR_ALIGNED() macro

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Hi.

2017-03-30 6:24 GMT+09:00 H. Peter Anvin <hpa@zytor.com>:
> On 03/29/17 03:22, Masahiro Yamada wrote:
>> We often check if a pointer has a specific alignment.  Because the
>> '&' (bitwise AND) operator cannot take a pointer for the operand,
>> so we need a cast like, IS_ALIGNED((unsigned long)p, a).
>>
>> IS_PTR_ALIGNED will be useful as a shorthand.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> ---
>>
>>  include/linux/kernel.h | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
>> index e5edd55..a810e4b 100644
>> --- a/include/linux/kernel.h
>> +++ b/include/linux/kernel.h
>> @@ -50,6 +50,7 @@
>>  #define __ALIGN_MASK(x, mask)        __ALIGN_KERNEL_MASK((x), (mask))
>>  #define PTR_ALIGN(p, a)              ((typeof(p))ALIGN((unsigned long)(p), (a)))
>>  #define IS_ALIGNED(x, a)             (((x) & ((typeof(x))(a) - 1)) == 0)
>> +#define IS_PTR_ALIGNED(p, a)         (IS_ALIGNED((unsigned long)p, a))
>>
>
> No need for two macros; make one work for both.
>
> You could move the __inttype() macro from arch/x86/include/asm/uaccess.h
> into this file and replace typeof(x) with __inttype(x) in the above macro.
>
> Attached is a set of slightly improved (safer and a bit more
> generalized) versions of the same macro that might be more appropriate
> to include in <linux/kernel.h>.
>
>         -hpa


Could you care to send a patch?

Perhaps, ALIGN and PTR_ALIGN can be merged as well?



-- 
Best Regards
Masahiro Yamada

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[PATCH] kernel.h: add IS_PTR_ALIGNED() macro Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-03-29 12:30 +0200
  Re: [PATCH] kernel.h: add IS_PTR_ALIGNED() macro Andrew Morton <akpm@linux-foundation.org> - 2017-03-29 23:40 +0200
  Re: [PATCH] kernel.h: add IS_PTR_ALIGNED() macro "H. Peter Anvin" <hpa@zytor.com> - 2017-03-29 23:40 +0200
    Re: [PATCH] kernel.h: add IS_PTR_ALIGNED() macro Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-03-30 04:00 +0200
      Re: [PATCH] kernel.h: add IS_PTR_ALIGNED() macro "H. Peter Anvin" <hpa@zytor.com> - 2017-03-30 05:50 +0200
        Re: [PATCH] kernel.h: add IS_PTR_ALIGNED() macro Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-03-30 17:30 +0200

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