Messages in this thread Patch in this message |  | | From | Benno Lossin <> | | Subject | [PATCH 2/2] rust: derive `Zeroable` for all structs & unions generated by bindgen where possible | | Date | Tue, 20 May 2025 21:23:06 +0200 |
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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.
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 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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