[PATCH v3 12/27] rust: auxiliary: make Driver trait lifetime-parameterized

[Danilo Krummrich <dakr@kernel.org>]

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 unbind() 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.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/gpu/drm/nova/driver.rs        |  7 +++++--
 rust/kernel/auxiliary.rs              | 14 ++++++++------
 samples/rust/rust_driver_auxiliary.rs |  7 +++++--
 3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/nova/driver.rs b/drivers/gpu/drm/nova/driver.rs
index 08136ec0bccb..1d73c595dda4 100644
--- a/drivers/gpu/drm/nova/driver.rs
+++ b/drivers/gpu/drm/nova/driver.rs
@@ -51,10 +51,13 @@ pub(crate) struct NovaData {
 
 impl auxiliary::Driver for NovaDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
     const ID_TABLE: auxiliary::IdTable<Self::IdInfo> = &AUX_TABLE;
 
-    fn probe(adev: &auxiliary::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        adev: &'bound auxiliary::Device<Core>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         let data = try_pin_init!(NovaData { adev: adev.into() });
 
         let drm = drm::Device::<Self>::new(adev.as_ref(), data)?;
diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index c6d97c95c3e7..3f1e2966c03a 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -46,7 +46,7 @@
 // - `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::auxiliary_driver;
-    type DriverData<'bound> = T::Data;
+    type DriverData<'bound> = T::Data<'bound>;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
@@ -112,7 +112,7 @@ extern "C" fn remove_callback(adev: *mut bindings::auxiliary_device) {
         // SAFETY: `remove_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 { adev.as_ref().drvdata_borrow::<T::Data>() };
+        let data = unsafe { adev.as_ref().drvdata_borrow::<T::Data<'_>>() };
 
         T::unbind(adev, data);
     }
@@ -203,7 +203,7 @@ pub trait Driver {
     type IdInfo: 'static;
 
     /// The type of the driver's bus device private data.
-    type Data;
+    type Data<'bound>: 'bound;
 
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
@@ -211,8 +211,10 @@ pub trait Driver {
     /// Auxiliary driver probe.
     ///
     /// Called when an auxiliary device is matches a corresponding driver.
-    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
-        -> impl PinInit<Self::Data, Error>;
+    fn probe<'bound>(
+        dev: &'bound Device<device::Core>,
+        id_info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 
     /// Auxiliary driver unbind.
     ///
@@ -224,7 +226,7 @@ fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo)
     /// operations to gracefully tear down the device.
     ///
     /// Otherwise, release operations for driver resources should be performed in `Drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self::Data>) {
+    fn unbind<'bound>(dev: &'bound Device<device::Core>, this: Pin<&'bound Self::Data<'bound>>) {
         let _ = (dev, this);
     }
 }
diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index 2f57912fe87f..972a3d5b25e7 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -31,11 +31,14 @@
 
 impl auxiliary::Driver for AuxiliaryDriver {
     type IdInfo = ();
-    type Data = Self;
+    type Data<'bound> = Self;
 
     const ID_TABLE: auxiliary::IdTable<Self::IdInfo> = &AUX_TABLE;
 
-    fn probe(adev: &auxiliary::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
+    fn probe<'bound>(
+        adev: &'bound auxiliary::Device<Core>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self, Error> + 'bound {
         dev_info!(
             adev,
             "Probing auxiliary driver for auxiliary device with id={}\n",
-- 
2.54.0