On Mon, May 02, 2022 at 01:06:56PM -0700, Yury Norov wrote:
> On Fri, Apr 29, 2022 at 08:45:35AM -0700, Yury Norov wrote:
> > On Fri, Apr 29, 2022 at 03:59:25PM +0300, Andy Shevchenko wrote:
> > > On Thu, Apr 28, 2022 at 01:51:13PM -0700, Yury Norov wrote:
...
> > > > +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. */
in the last
> > > > + 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?
> >
> > BITS_TO_LONGS(0) == 0
> > BITS_TO_LONGS(1..32) == 1
> > BITS_TO_LONGS(33..64) == 2
> >
> > The only potential problem with buf[-1] is nbits == 0, but fortunately
> > (0 % 64) == 0, and it doesn't happen.
I see, perhaps adding a small comment would be nice to have to explain that -1
index is safe.
> Are there any other concerns? If no, I'll fix formatting and append it to
> bitmap-for-next.
Nope.
--
With Best Regards,
Andy Shevchenko
