On Fri Jul 4, 2025 at 12:10 AM EDT, FUJITA Tomonori wrote:
> Introduce a new trait `RawDeviceIdIndex`, which extends `RawDeviceId`
> to provide support for device ID types that include an index or
> context field (e.g., `driver_data`). This separates the concerns of
> layout compatibility and index-based data embedding, and allows
> `RawDeviceId` to be implemented for types that do not contain a
> `driver_data` field. Several such structures are defined in
> include/linux/mod_devicetable.h.
>
> Refactor `IdArray::new()` into a generic `build()` function, which
> takes an optional offset. Based on the presence of `RawDeviceIdIndex`,
> index writing is conditionally enabled. A new `new_without_index()`
> constructor is also provided for use cases where no index should be
> written.
>
> This refactoring is a preparation for enabling the PHY abstractions to
> use device_id trait.
>
> Acked-by: Danilo Krummrich <dakr@xxxxxxxxxx>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxx>
> ---
> rust/kernel/auxiliary.rs | 11 ++---
> rust/kernel/device_id.rs | 91 ++++++++++++++++++++++++++++------------
> rust/kernel/of.rs | 15 ++++---
> rust/kernel/pci.rs | 11 ++---
> 4 files changed, 87 insertions(+), 41 deletions(-)
Few small suggestions if you wind up spinning this again:
> diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs
> [...]
> @@ -68,7 +77,14 @@ impl<T: RawDeviceId, U, const N: usize> IdArray<T, U, N> {
> /// Creates a new instance of the array.
> ///
> /// The contents are derived from the given identifiers and context information.
> - pub const fn new(ids: [(T, U); N]) -> Self {
> + ///
> + /// # Safety
> + ///
> + /// If `offset` is `Some(offset)`, then:
> + /// - `offset` must be the correct offset (in bytes) to the context/data field
> + /// (e.g., the `driver_data` field) within the raw device ID structure.
> + /// - The field at `offset` must be correctly sized to hold a `usize`.
> + const unsafe fn build(ids: [(T, U); N], offset: Option<usize>) -> Self {
Could you mention that calling with `offset` as `None` is always safe?
Also calling the arg `data_offset` might be more clear.
> @@ -92,7 +111,6 @@ impl<T: RawDeviceId, U, const N: usize> IdArray<T, U, N> {
> infos[i] = MaybeUninit::new(unsafe { core::ptr::read(&ids[i].1) });
> i += 1;
> }
> -
> core::mem::forget(ids);
This removes the space between a block and an expression, possibly
unintentional? :)
> @@ -109,12 +127,33 @@ impl<T: RawDeviceId, U, const N: usize> IdArray<T, U, N> {
> }
> }
>
> + /// Creates a new instance of the array without writing index values.
> + ///
> + /// The contents are derived from the given identifiers and context information.
Maybe the docs here should crosslink:
If the device implements [`RawDeviceIdIndex`], consider using
[`new`] instead.
> + pub const fn new_without_index(ids: [(T, U); N]) -> Self {
> + // SAFETY: Calling `Self::build` with `offset = None` is always safe,
> + // because no raw memory writes are performed in this case.
> + unsafe { Self::build(ids, None) }
> + }
> +
With those changes, or as-is if there winds up not being another
version:
Reviewed-by: Trevor Gross <tmgross@xxxxxxxxx>
