On Thu, Apr 28, 2022 at 01:51:13PM -0700, Yury Norov wrote:
> Manipulating 64-bit arrays with bitmap functions is potentially dangerous
> because on 32-bit BE machines the order of halfwords doesn't match.
> Another issue is that compiler may throw a warning about out-of-boundary
> access.
>
> This patch adds bitmap_{from,to}_arr64 functions in addition to existing
> bitmap_{from,to}_arr32.
...
> + bitmap_copy_clear_tail((unsigned long *) (bitmap), \
> + (const unsigned long *) (buf), (nbits))
Drop spaces after castings. Besides that it might be placed on a single line.
...
> + bitmap_copy_clear_tail((unsigned long *) (buf), \
> + (const unsigned long *) (bitmap), (nbits))
Ditto.
...
> +void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits)
> +{
> + const unsigned long *end = bitmap + BITS_TO_LONGS(nbits);
> +
> + while (bitmap < end) {
> + *buf = *bitmap++;
> + if (bitmap < end)
> + *buf |= (u64)(*bitmap++) << 32;
> + buf++;
> + }
>
> + /* Clear tail bits in last element of array beyond nbits. */
> + if (nbits % 64)
> + buf[-1] &= GENMASK_ULL(nbits, 0);
Hmm... if nbits is > 0 and < 64, wouldn't be this problematic, since
end == bitmap? Or did I miss something?
> +}
--
With Best Regards,
Andy Shevchenko
