On Mon, Jul 06, 2026 at 12:29:00PM -0400, Yury Norov wrote: > On Fri, Jul 03, 2026 at 07:16:05PM +0900, Eliot Courtney wrote: > > Add bindings and helpers for area operations on bitmaps. Each one is > > made safe by adding some extra checks compared to the underlying C code > > (for example, checking bounds) and with additional checks to catch > > likely erroneous usage if `CONFIG_RUST_BITMAP_HARDENED` is on. > > > > The C code uses signed integers for some parameters, for example the > > length for `__bitmap_set`, so bounds check against i32::MAX. We can't > > rely on `BitmapVec::MAX_LEN` because `Bitmap` may not necessarily be > > backed by `BitmapVec`. There's also a few cases where a non power of two > > minus one `align_mask` can cause an infinite loop in the C code (can > > happen on overflow), so check for that. > > > > Add tests demonstrating the edge cases. > > > > Signed-off-by: Eliot Courtney <[email protected]> > > --- > > rust/helpers/bitmap.c | 22 +++++ > > rust/kernel/bitmap.rs | 219 > > ++++++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 241 insertions(+) > > > > diff --git a/rust/helpers/bitmap.c b/rust/helpers/bitmap.c > > index e4e9f4361270..dac5c03f2448 100644 > > --- a/rust/helpers/bitmap.c > > +++ b/rust/helpers/bitmap.c > > @@ -8,3 +8,25 @@ void rust_helper_bitmap_copy_and_extend(unsigned long *to, > > const unsigned long * > > { > > bitmap_copy_and_extend(to, from, count, size); > > } > > + > > +__rust_helper > > +unsigned long rust_helper_bitmap_find_next_zero_area(unsigned long *map, > > + unsigned long size, > > + unsigned long start, > > + unsigned int nr, > > + unsigned long align_mask) > > +{ > > + return bitmap_find_next_zero_area(map, size, start, nr, align_mask); > > +} > > + > > +__rust_helper > > +void rust_helper_bitmap_set(unsigned long *map, unsigned int start, > > unsigned int nbits) > > +{ > > + bitmap_set(map, start, nbits); > > +} > > + > > +__rust_helper > > +void rust_helper_bitmap_clear(unsigned long *map, unsigned int start, > > unsigned int nbits) > > +{ > > + bitmap_clear(map, start, nbits); > > +} > > All three are the wrappers around the regular outline functions: > bitmap_find_next_zero_area_off(), __bitmap_set() and __bitmap_clear(). > > The inlined version in headers is optimized for small bitmaps. But the > optimization is all based on inlining in the C code. It doesn't work > if you wrap it with a rust helper. > > There was a discussion about the similar find_next_bit(). The function > itself is an inliner, but it's a wrapper around the true outlined > _find_next_bit(). So we decided to minimize the binder size for that > type of functions. > > Please, keep the binder minimal unless necessary.
If we can just call __bitmap_clear() without any downsides, then I agree we should do that, but we actually do support inlining the helpers now. See CONFIG_RUST_INLINE_HELPERS. Alice
