On Tue, Jul 18, 2023 at 11:30:00AM +0200, Alexander Potapenko wrote:

On Mon, Jul 17, 2023 at 5:51 PM Yury Norov [off-list ref] wrote:

quoted

On Mon, Jul 17, 2023 at 01:37:04PM +0200, Alexander Potapenko wrote:

...

quoted

When nbits == 0, copy-like functions shouldn't touch any memory. See how
other bitmap and find_bit functions hold it.

I think this is different from what other bitmap functions do, but it
should be enough to bail out on !nbits, i.e.:

    if (!nbits)
        return 0;

You probably meant adding a __builtin_constant_p() (which is used all
over the place in bitmap.h), but:
 - the compiler won't have problem optimizing away the code for a
constant nbits=0;
 - we anyway need a dynamic check for the case nbits is not constant
(for both bitmap_get_value() and bitmap_set_value(), I assume).

What do you think?

The idea behind is to eliminate the code completely for the cases nbits != 0.
In your case the dynamic check will be there. That's what we want to avoid.

-- 
With Best Regards,
Andy Shevchenko



_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel