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

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Message-ID: <ZN8w5CbGn2CkYCDy@smile.fi.intel.com>
Date:   Fri, 18 Aug 2023 11:50:44 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
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 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?

...

> > -		return !memcmp(src1, src2, nbits / 8);
> > +		return !memcmp(src1, src2, BITS_TO_BYTES(nbits));
> 
> Please no. Currently, I can verify the arithmetic directly. Using such a
> "helper" I'd have to know whether it just does /8 or if it's more like
> the bitmap_words() thing which rounds up to a whole number of words. And
> BITS_PER_BYTE (and similarly CHAR_BITS) really is, IMO, much less
> readable than 8.

Okay, thank you for the comment!

-- 
With Best Regards,
Andy Shevchenko