On Tue, 08 Jul 2025 23:10:48 -0400
"Trevor Gross" <tmgross@xxxxxxxxx> wrote:
> 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?
Indeed, added.
> Also calling the arg `data_offset` might be more clear.
Yeah, changed.
>> @@ -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? :)
Oops, unintentional. Dropped the change.
>> @@ -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.
Looks nice, added. [`new`] doesn't work so I use [`IdArray::new`].
>> + 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>
Thanks!
