On Thu, Oct 05, 2023 at 10:03:49AM +0200, Köry Maincent wrote:
> Hello Simon,
>
> Thank for your review.
>
> On Wed, 4 Oct 2023 13:07:14 +0200
> Simon Horman <horms@xxxxxxxxxx> wrote:
>
> > On Tue, Oct 03, 2023 at 10:56:52AM +0200, Köry Maincent wrote:
> > > From: Kory Maincent <kory.maincent@xxxxxxxxxxx>
> >
> > > @@ -448,8 +450,11 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned
> > > int nbits, }
> > >
> > > no_mask = tb[ETHTOOL_A_BITSET_NOMASK];
> > > - if (no_mask)
> > > - ethnl_bitmap32_clear(bitmap, 0, nbits, mod);
> > > + if (no_mask) {
> > > + tmp = kcalloc(nbits, sizeof(u32), GFP_KERNEL);
> > > + memcpy(tmp, bitmap, nbits);
> >
> > Hi Köry,
> >
> > I'm no expert on etnhl bitmaps. But the above doesn't seem correct to me.
> > Given that sizeof(u32) == 4:
> >
> > * The allocation is for nbits * 4 bytes
> > * The copy is for its for nbits bytes
> > * I believe that bitmap contains space for the value followed by a mask.
> > So it seems to me the size of bitmap, in words, is
> > DIV_ROUND_UP(nbits, 32) * 2
> > And in bytes: DIV_ROUND_UP(nbits, 32) * 16
> > But perhaps only half is needed if only the value part of tmp is used.
> >
> > If I'm on the right track here I'd suggest helpers might be in order.
>
> You are right I should use the same alloc as ethnl_update_bitset with tmp
> instead of bitmap32:
>
> u32 small_bitmap32[ETHNL_SMALL_BITMAP_WORDS];
> u32 *bitmap32 = small_bitmap32;
> if (nbits > ETHNL_SMALL_BITMAP_BITS) {
> unsigned int dst_words = DIV_ROUND_UP(nbits, 32);
>
> bitmap32 = kmalloc_array(dst_words, sizeof(u32), GFP_KERNEL);
> if (!bitmap32)
> return -ENOMEM;
> }
>
> But I am still wondering if it needs to be double as you said for the size of
> the value followed by the mask. Not sure about it, as ethnl_update_bitset does
> not do it.
If you only need the value, then I don' think you need to x2 the allocation.
But I could be wrong.
