Messages in this thread |  | | From | Alice Ryhl <> | | Date | Tue, 20 May 2025 14:38:10 -0700 | | Subject | Re: [PATCH 2/2] rust: derive `Zeroable` for all structs & unions generated by bindgen where possible |
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On Tue, May 20, 2025 at 12:23 PM Benno Lossin <lossin@kernel.org> wrote: > > Using the `--with-derive-custom-{struct,union}` option of bindgen, add > `#[derive(MaybeZeroable)]` to every struct & union. This makes those > types implement `Zeroable` if all their fields implement it.
I think this is a great idea.
> Sadly bindgen doesn't add custom derives to the `__BindgenBitfieldUnit` > struct. So manually implement `Zeroable` for that. > > Signed-off-by: Benno Lossin <lossin@kernel.org> > --- > > This came from a discussion at [1]. The relevant parts for pin-init > already got merged into rust-next for v6.16, so we only need to enable > them for bindgen. > > I'm not sure on the impact of build times and rust-analyzer. We're > adding a derive macro to every struct and union emitted by bindgen. > Building using my test-config took 28.6s before and 29.1s after this > change, but those are only two runs. > > Maybe we have to reevaluate this when more C code is scanned by bindgen. > > [1]: https://rust-for-linux.zulipchat.com/#narrow/channel/291565-Help/topic/Zeroable.20trait.20for.20C.20structs/with/509711564 > > --- > rust/bindgen_parameters | 4 ++++ > rust/bindings/lib.rs | 9 +++++++++ > 2 files changed, 13 insertions(+) > > diff --git a/rust/bindgen_parameters b/rust/bindgen_parameters > index 0f96af8b9a7f..fa4c61ba028f 100644 > --- a/rust/bindgen_parameters > +++ b/rust/bindgen_parameters > @@ -34,3 +34,7 @@ > # We use const helpers to aid bindgen, to avoid conflicts when constants are > # recognized, block generation of the non-helper constants. > --blocklist-item ARCH_SLAB_MINALIGN > + > +# Structs should implement Zeroable when all of their fields do. > +--with-derive-custom-struct .*=pin_init::MaybeZeroable > +--with-derive-custom-union .*=pin_init::MaybeZeroable
Maybe add an import in bindings/lib.rs and use it directly? Seems a bit nicer to read without the prefix.
> diff --git a/rust/bindings/lib.rs b/rust/bindings/lib.rs > index a08eb5518cac..38615c5b090d 100644 > --- a/rust/bindings/lib.rs > +++ b/rust/bindings/lib.rs > @@ -33,6 +33,15 @@ mod bindings_raw { > type __kernel_ssize_t = isize; > type __kernel_ptrdiff_t = isize; > > + // `bindgen` doesn't automatically do this, see > + // <https://github.com/rust-lang/rust-bindgen/issues/3196> > + // > + // SAFETY: `__BindgenBitfieldUnit<Storage>` is a newtype around `Storage`. > + unsafe impl<Storage> pin_init::Zeroable for __BindgenBitfieldUnit<Storage> where > + Storage: pin_init::Zeroable > + { > + } > + > // Use glob import here to expose all helpers. > // Symbols defined within the module will take precedence to the glob import. > pub use super::bindings_helper::*; > -- > 2.49.0 >
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