> On 25 May 2026, at 17:21, Danilo Krummrich <[email protected]> wrote:
>
> Add a 'bound lifetime to the associated Data, changing type Data to type
> Data<'bound>.
>
> This allows the driver's bus device private data to capture the device /
> driver bound lifetime; device resources can be stored directly by
> reference rather than requiring Devres.
>
> The probe() and disconnect() callbacks thus gain a 'bound lifetime
> parameter on the methods themselves; avoiding a global lifetime on the
> trait impl.
>
> Existing drivers set type Data<'bound> = Self, preserving the current
> behavior.
>
> Reviewed-by: Alexandre Courbot <[email protected]>
> Reviewed-by: Greg Kroah-Hartman <[email protected]>
> Reviewed-by: Eliot Courtney <[email protected]>
> Signed-off-by: Danilo Krummrich <[email protected]>
> ---
> rust/kernel/usb.rs | 37 ++++++++++++++++++++-------------
> samples/rust/rust_driver_usb.rs | 12 +++++------
> 2 files changed, 28 insertions(+), 21 deletions(-)
>
> diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
> index 1dbb8387b463..7aff0c82d0af 100644
> --- a/rust/kernel/usb.rs
> +++ b/rust/kernel/usb.rs
> @@ -41,7 +41,7 @@
> // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded
> `struct device_driver`.
> unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
> type DriverType = bindings::usb_driver;
> - type DriverData<'bound> = T::Data;
> + type DriverData<'bound> = T::Data<'bound>;
> const DEVICE_DRIVER_OFFSET: usize =
> core::mem::offset_of!(Self::DriverType, driver);
> }
>
> @@ -109,8 +109,8 @@ extern "C" fn disconnect_callback(intf: *mut
> bindings::usb_interface) {
>
> // SAFETY: `disconnect_callback` is only ever called after a
> successful call to
> // `probe_callback`, hence it's guaranteed that
> `Device::set_drvdata()` has been called
> - // and stored a `Pin<KBox<T::Data>>`.
> - let data = unsafe { dev.drvdata_borrow::<T::Data>() };
> + // and stored a `Pin<KBox<T::Data<'_>>>`.
> + let data = unsafe { dev.drvdata_borrow::<T::Data<'_>>() };
>
> T::disconnect(intf, data);
> }
> @@ -287,18 +287,22 @@ macro_rules! usb_device_table {
> ///
> /// impl usb::Driver for MyDriver {
> /// type IdInfo = ();
> -/// type Data = Self;
> +/// type Data<'bound> = Self;
> /// const ID_TABLE: usb::IdTable<Self::IdInfo> = &USB_TABLE;
> ///
> -/// fn probe(
> -/// _interface: &usb::Interface<Core<'_>>,
> +/// fn probe<'bound>(
> +/// _interface: &'bound usb::Interface<Core<'_>>,
> /// _id: &usb::DeviceId,
> -/// _info: &Self::IdInfo,
> -/// ) -> impl PinInit<Self::Data, Error> {
> +/// _info: &'bound Self::IdInfo,
> +/// ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
> /// Err(ENODEV)
> /// }
> ///
> -/// fn disconnect(_interface: &usb::Interface<Core<'_>>, _data:
> Pin<&Self::Data>) {}
> +/// fn disconnect<'bound>(
> +/// _interface: &'bound usb::Interface<Core<'_>>,
> +/// _data: Pin<&Self::Data<'bound>>,
> +/// ) {
> +/// }
> /// }
> ///```
> pub trait Driver {
> @@ -306,7 +310,7 @@ pub trait Driver {
> type IdInfo: 'static;
>
> /// The type of the driver's bus device private data.
> - type Data: Send;
> + type Data<'bound>: Send + 'bound;
>
> /// The table of device ids supported by the driver.
> const ID_TABLE: IdTable<Self::IdInfo>;
> @@ -315,16 +319,19 @@ pub trait Driver {
> ///
> /// Called when a new USB interface is bound to this driver.
> /// Implementers should attempt to initialize the interface here.
> - fn probe(
> - interface: &Interface<device::Core<'_>>,
> + fn probe<'bound>(
> + interface: &'bound Interface<device::Core<'_>>,
> id: &DeviceId,
> - id_info: &Self::IdInfo,
> - ) -> impl PinInit<Self::Data, Error>;
> + id_info: &'bound Self::IdInfo,
> + ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
>
> /// USB driver disconnect.
> ///
> /// Called when the USB interface is about to be unbound from this driver.
> - fn disconnect(interface: &Interface<device::Core<'_>>, data:
> Pin<&Self::Data>);
> + fn disconnect<'bound>(
> + interface: &'bound Interface<device::Core<'_>>,
> + data: Pin<&Self::Data<'bound>>,
> + );
> }
>
> /// A USB interface.
> diff --git a/samples/rust/rust_driver_usb.rs b/samples/rust/rust_driver_usb.rs
> index e900993335e9..02bd5085f9bc 100644
> --- a/samples/rust/rust_driver_usb.rs
> +++ b/samples/rust/rust_driver_usb.rs
> @@ -26,21 +26,21 @@ struct SampleDriver {
>
> impl usb::Driver for SampleDriver {
> type IdInfo = ();
> - type Data = Self;
> + type Data<'bound> = Self;
> const ID_TABLE: usb::IdTable<Self::IdInfo> = &USB_TABLE;
>
> - fn probe(
> - intf: &usb::Interface<Core<'_>>,
> + fn probe<'bound>(
> + intf: &'bound usb::Interface<Core<'_>>,
> _id: &usb::DeviceId,
> - _info: &Self::IdInfo,
> - ) -> impl PinInit<Self, Error> {
> + _info: &'bound Self::IdInfo,
> + ) -> impl PinInit<Self, Error> + 'bound {
> let dev: &device::Device<Core<'_>> = intf.as_ref();
> dev_info!(dev, "Rust USB driver sample probed\n");
>
> Ok(Self { _intf: intf.into() })
> }
>
> - fn disconnect(intf: &usb::Interface<Core<'_>>, _data: Pin<&Self>) {
> + fn disconnect<'bound>(intf: &'bound usb::Interface<Core<'_>>, _data:
> Pin<&Self>) {
> let dev: &device::Device<Core<'_>> = intf.as_ref();
> dev_info!(dev, "Rust USB driver sample disconnected\n");
> }
> --
> 2.54.0
>
>
Reviewed-by: Daniel Almeida <[email protected]>
