linux-kernel - Re: [PATCH v1 1/2] bitmap: Use constants and macros from bits.h

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Date:   Fri, 18 Aug 2023 11:13:27 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Yury Norov <yury.norov@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] bitmap: Use constants and macros from bits.h

On 18/08/2023 10.50, Andy Shevchenko wrote:
> On Fri, Aug 18, 2023 at 08:28:21AM +0200, Rasmus Villemoes wrote:
>> On 17/08/2023 18.54, Andy Shevchenko wrote:
> 
>>>  #ifdef __LITTLE_ENDIAN
>>> -#define BITMAP_MEM_ALIGNMENT 8
>>> +#define BITMAP_MEM_ALIGNMENT	BITS_PER_BYTE
>>>  #else
>>> -#define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
>>> +#define BITMAP_MEM_ALIGNMENT	BITS_PER_LONG
>>>  #endif
>>>  #define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
> 
> What about this chunk? Does it worth to be updated?

IMHO, no, not in this way anyway. But the macros could perhaps use a
comment saying that they decide whether certain bitmap operations can be
turned into plain memxxx calls, which is why LE vs BE matters, and LE
just needs the bitmap to consist of a whole number of bytes while for BE
it must be a whole number of longs.

Rasmus