linux-kernel - Re: [PATCH v2 2/6] bitmap: replace _reg_op(REG_OP_ALLOC) with bitmap

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Date:   Fri, 11 Aug 2023 06:01:58 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH v2 2/6] bitmap: replace _reg_op(REG_OP_ALLOC) with
 bitmap_set()

On Fri, Aug 11, 2023 at 12:25:02PM +0300, Andy Shevchenko wrote:
> On Thu, Aug 10, 2023 at 05:57:28PM -0700, Yury Norov wrote:
> > _reg_op(REG_OP_ALLOC) duplicates bitmap_set(). Fix it.
> 
> ...
> 
> >  int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
> >  {
> > +	unsigned int nbits = pos + BIT(order);
> 
> Shouldn't this be unsigned long?
> As the prototype of the used later unsigned long find_next_bit().

Linux doesn't support bitmaps longer than 2^32 bits. I really doubt
such huge bitmaps would ever exist, but if that will happen, too many
bitmap functions will have to be revisited.

For the reference, check the code of __reg_op(), which I remove in the
series - all indexes and offsets are int's there.

Thanks,
Yury
 
> >  	if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
> >  		return -EBUSY;
> > -	return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
> > +	bitmap_set(bitmap, pos, nbits);
> > +	return 0;
> >  }
> 
> -- 
> With Best Regards,
> Andy Shevchenko
>