[PATCH v5 14/24] rust: auxiliary: make Driver trait lifetime-parameterized

[Danilo Krummrich]

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.

Reviewed-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 drivers/gpu/drm/nova/driver.rs        | 10 +++++-----
 rust/kernel/auxiliary.rs              | 18 +++++++++---------
 samples/rust/rust_driver_auxiliary.rs | 10 +++++-----
 3 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/nova/driver.rs b/drivers/gpu/drm/nova/driver.rs
index 7605348af994..aa08644012f7 100644
--- a/drivers/gpu/drm/nova/driver.rs
+++ b/drivers/gpu/drm/nova/driver.rs
@@ -51,13 +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 6d504b0933d5..7a1b1a7b7ca6 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);
 }
 
@@ -111,8 +111,8 @@ 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>() };
+        // and stored a `Pin<KBox<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: Send;
+    type Data<'bound>: Send + 'bound;
 
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
@@ -211,10 +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.
     ///
@@ -226,7 +226,7 @@ fn probe(
     /// 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<&Self::Data<'bound>>) {
         let _ = (dev, this);
     }
 }
diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index 0e979f45cd68..b30a4d5cdf8a 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -31,14 +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