Merge tag 'driver-core-6.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

Pull driver core fixes from Danilo Krummrich:

- Always inline I/O and IRQ methods using build_assert!() to avoid
false positive build errors

- Do not free the driver's device private data in I2C shutdown()
avoiding race conditions that can lead to UAF bugs

- Drop the driver's device private data after the driver has been
fully unbound from its device to avoid UAF bugs from &Device<Bound>
scopes, such as IRQ callbacks

* tag 'driver-core-6.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core:
rust: driver: drop device private data post unbind
rust: driver: add DriverData type to the DriverLayout trait
rust: driver: add DEVICE_DRIVER_OFFSET to the DriverLayout trait
rust: driver: introduce a DriverLayout trait
rust: auxiliary: add Driver::unbind() callback
rust: i2c: do not drop device private data on shutdown()
rust: irq: always inline functions using build_assert with arguments
rust: io: always inline functions using build_assert with arguments

drivers/base/dd.c

···
 static void device_unbind_cleanup(struct device *dev)
 {
 	devres_release_all(dev);
+	if (dev->driver->p_cb.post_unbind_rust)
+		dev->driver->p_cb.post_unbind_rust(dev);
 	arch_teardown_dma_ops(dev);
 	kfree(dev->dma_range_map);
 	dev->dma_range_map = NULL;

include/linux/device/driver.h

···
  *		uevent.
  * @p:		Driver core's private data, no one other than the driver
  *		core can touch this.
+ * @p_cb:	Callbacks private to the driver core; no one other than the
+ *		driver core is allowed to touch this.
  *
  * The device driver-model tracks all of the drivers known to the system.
  * The main reason for this tracking is to enable the driver core to match
···
 	void (*coredump) (struct device *dev);
 
 	struct driver_private *p;
+	struct {
+		/*
+		 * Called after remove() and after all devres entries have been
+		 * processed. This is a Rust only callback.
+		 */
+		void (*post_unbind_rust)(struct device *dev);
+	} p_cb;
 };
 
 

rust/kernel/auxiliary.rs

···
 /// An adapter for the registration of auxiliary drivers.
 pub struct Adapter<T: Driver>(T);
 
-// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
+// SAFETY:
+// - `bindings::auxiliary_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
+// - `struct auxiliary_driver` embeds a `struct device_driver`.
+// - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
+unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+    type DriverType = bindings::auxiliary_driver;
+    type DriverData = T;
+    const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
+}
+
+// SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
 unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
-    type RegType = bindings::auxiliary_driver;
-
     unsafe fn register(
-        adrv: &Opaque<Self::RegType>,
+        adrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result {
···
             (*adrv.get()).id_table = T::ID_TABLE.as_ptr();
         }
 
-        // SAFETY: `adrv` is guaranteed to be a valid `RegType`.
+        // SAFETY: `adrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe {
             bindings::__auxiliary_driver_register(adrv.get(), module.0, name.as_char_ptr())
         })
     }
 
-    unsafe fn unregister(adrv: &Opaque<Self::RegType>) {
-        // SAFETY: `adrv` is guaranteed to be a valid `RegType`.
+    unsafe fn unregister(adrv: &Opaque<Self::DriverType>) {
+        // SAFETY: `adrv` is guaranteed to be a valid `DriverType`.
         unsafe { bindings::auxiliary_driver_unregister(adrv.get()) }
     }
 }
···
         // 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>>`.
-        drop(unsafe { adev.as_ref().drvdata_obtain::<T>() });
+        let data = unsafe { adev.as_ref().drvdata_borrow::<T>() };
+
+        T::unbind(adev, data);
     }
 }
 
···
     ///
     /// Called when an auxiliary device is matches a corresponding driver.
     fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo) -> impl PinInit<Self, Error>;
+
+    /// Auxiliary driver unbind.
+    ///
+    /// Called when a [`Device`] is unbound from its bound [`Driver`]. Implementing this callback
+    /// is optional.
+    ///
+    /// This callback serves as a place for drivers to perform teardown operations that require a
+    /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
+    /// operations to gracefully tear down the device.
+    ///
+    /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
+    fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
+        let _ = (dev, this);
+    }
 }
 
 /// The auxiliary device representation.

rust/kernel/device.rs

···
     ///
     /// # Safety
     ///
-    /// - Must only be called once after a preceding call to [`Device::set_drvdata`].
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    pub unsafe fn drvdata_obtain<T: 'static>(&self) -> Pin<KBox<T>> {
+    pub(crate) unsafe fn drvdata_obtain<T: 'static>(&self) -> Option<Pin<KBox<T>>> {
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };
 
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         unsafe { bindings::dev_set_drvdata(self.as_raw(), core::ptr::null_mut()) };
 
+        if ptr.is_null() {
+            return None;
+        }
+
         // SAFETY:
-        // - By the safety requirements of this function, `ptr` comes from a previous call to
-        //   `into_foreign()`.
+        // - If `ptr` is not NULL, it comes from a previous call to `into_foreign()`.
         // - `dev_get_drvdata()` guarantees to return the same pointer given to `dev_set_drvdata()`
         //   in `into_foreign()`.
-        unsafe { Pin::<KBox<T>>::from_foreign(ptr.cast()) }
+        Some(unsafe { Pin::<KBox<T>>::from_foreign(ptr.cast()) })
     }
 
     /// Borrow the driver's private data bound to this [`Device`].
     ///
     /// # Safety
     ///
-    /// - Must only be called after a preceding call to [`Device::set_drvdata`] and before
-    ///   [`Device::drvdata_obtain`].
+    /// - Must only be called after a preceding call to [`Device::set_drvdata`] and before the
+    ///   device is fully unbound.
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
     pub unsafe fn drvdata_borrow<T: 'static>(&self) -> Pin<&T> {
···
     /// # Safety
     ///
     /// - Must only be called after a preceding call to [`Device::set_drvdata`] and before
-    ///   [`Device::drvdata_obtain`].
+    ///   the device is fully unbound.
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
     unsafe fn drvdata_unchecked<T: 'static>(&self) -> Pin<&T> {
···
 
         // SAFETY:
         // - The above check of `dev_get_drvdata()` guarantees that we are called after
-        //   `set_drvdata()` and before `drvdata_obtain()`.
+        //   `set_drvdata()`.
         // - We've just checked that the type of the driver's private data is in fact `T`.
         Ok(unsafe { self.drvdata_unchecked() })
     }

rust/kernel/driver.rs

···
 use core::pin::Pin;
 use pin_init::{pin_data, pinned_drop, PinInit};
 
+/// Trait describing the layout of a specific device driver.
+///
+/// This trait describes the layout of a specific driver structure, such as `struct pci_driver` or
+/// `struct platform_driver`.
+///
+/// # Safety
+///
+/// Implementors must guarantee that:
+/// - `DriverType` is `repr(C)`,
+/// - `DriverData` is the type of the driver's device private data.
+/// - `DriverType` embeds a valid `struct device_driver` at byte offset `DEVICE_DRIVER_OFFSET`.
+pub unsafe trait DriverLayout {
+    /// The specific driver type embedding a `struct device_driver`.
+    type DriverType: Default;
+
+    /// The type of the driver's device private data.
+    type DriverData;
+
+    /// Byte offset of the embedded `struct device_driver` within `DriverType`.
+    ///
+    /// This must correspond exactly to the location of the embedded `struct device_driver` field.
+    const DEVICE_DRIVER_OFFSET: usize;
+}
+
 /// The [`RegistrationOps`] trait serves as generic interface for subsystems (e.g., PCI, Platform,
 /// Amba, etc.) to provide the corresponding subsystem specific implementation to register /
-/// unregister a driver of the particular type (`RegType`).
+/// unregister a driver of the particular type (`DriverType`).
 ///
-/// For instance, the PCI subsystem would set `RegType` to `bindings::pci_driver` and call
+/// For instance, the PCI subsystem would set `DriverType` to `bindings::pci_driver` and call
 /// `bindings::__pci_register_driver` from `RegistrationOps::register` and
 /// `bindings::pci_unregister_driver` from `RegistrationOps::unregister`.
 ///
 /// # Safety
 ///
-/// A call to [`RegistrationOps::unregister`] for a given instance of `RegType` is only valid if a
-/// preceding call to [`RegistrationOps::register`] has been successful.
-pub unsafe trait RegistrationOps {
-    /// The type that holds information about the registration. This is typically a struct defined
-    /// by the C portion of the kernel.
-    type RegType: Default;
-
+/// A call to [`RegistrationOps::unregister`] for a given instance of `DriverType` is only valid if
+/// a preceding call to [`RegistrationOps::register`] has been successful.
+pub unsafe trait RegistrationOps: DriverLayout {
     /// Registers a driver.
     ///
     /// # Safety
···
     /// On success, `reg` must remain pinned and valid until the matching call to
     /// [`RegistrationOps::unregister`].
     unsafe fn register(
-        reg: &Opaque<Self::RegType>,
+        reg: &Opaque<Self::DriverType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result;
···
     ///
     /// Must only be called after a preceding successful call to [`RegistrationOps::register`] for
     /// the same `reg`.
-    unsafe fn unregister(reg: &Opaque<Self::RegType>);
+    unsafe fn unregister(reg: &Opaque<Self::DriverType>);
 }
 
 /// A [`Registration`] is a generic type that represents the registration of some driver type (e.g.
···
 #[pin_data(PinnedDrop)]
 pub struct Registration<T: RegistrationOps> {
     #[pin]
-    reg: Opaque<T::RegType>,
+    reg: Opaque<T::DriverType>,
 }
 
 // SAFETY: `Registration` has no fields or methods accessible via `&Registration`, so it is safe to
···
 // any thread, so `Registration` is `Send`.
 unsafe impl<T: RegistrationOps> Send for Registration<T> {}
 
-impl<T: RegistrationOps> Registration<T> {
+impl<T: RegistrationOps + 'static> Registration<T> {
+    extern "C" fn post_unbind_callback(dev: *mut bindings::device) {
+        // SAFETY: The driver core only ever calls the post unbind callback with a valid pointer to
+        // a `struct device`.
+        //
+        // INVARIANT: `dev` is valid for the duration of the `post_unbind_callback()`.
+        let dev = unsafe { &*dev.cast::<device::Device<device::CoreInternal>>() };
+
+        // `remove()` and all devres callbacks have been completed at this point, hence drop the
+        // driver's device private data.
+        //
+        // SAFETY: By the safety requirements of the `Driver` trait, `T::DriverData` is the
+        // driver's device private data type.
+        drop(unsafe { dev.drvdata_obtain::<T::DriverData>() });
+    }
+
+    /// Attach generic `struct device_driver` callbacks.
+    fn callbacks_attach(drv: &Opaque<T::DriverType>) {
+        let ptr = drv.get().cast::<u8>();
+
+        // SAFETY:
+        // - `drv.get()` yields a valid pointer to `Self::DriverType`.
+        // - Adding `DEVICE_DRIVER_OFFSET` yields the address of the embedded `struct device_driver`
+        //   as guaranteed by the safety requirements of the `Driver` trait.
+        let base = unsafe { ptr.add(T::DEVICE_DRIVER_OFFSET) };
+
+        // CAST: `base` points to the offset of the embedded `struct device_driver`.
+        let base = base.cast::<bindings::device_driver>();
+
+        // SAFETY: It is safe to set the fields of `struct device_driver` on initialization.
+        unsafe { (*base).p_cb.post_unbind_rust = Some(Self::post_unbind_callback) };
+    }
+
     /// Creates a new instance of the registration object.
     pub fn new(name: &'static CStr, module: &'static ThisModule) -> impl PinInit<Self, Error> {
         try_pin_init!(Self {
-            reg <- Opaque::try_ffi_init(|ptr: *mut T::RegType| {
+            reg <- Opaque::try_ffi_init(|ptr: *mut T::DriverType| {
                 // SAFETY: `try_ffi_init` guarantees that `ptr` is valid for write.
-                unsafe { ptr.write(T::RegType::default()) };
+                unsafe { ptr.write(T::DriverType::default()) };
 
                 // SAFETY: `try_ffi_init` guarantees that `ptr` is valid for write, and it has
                 // just been initialised above, so it's also valid for read.
-                let drv = unsafe { &*(ptr as *const Opaque<T::RegType>) };
+                let drv = unsafe { &*(ptr as *const Opaque<T::DriverType>) };
+
+                Self::callbacks_attach(drv);
 
                 // SAFETY: `drv` is guaranteed to be pinned until `T::unregister`.
                 unsafe { T::register(drv, name, module) }

rust/kernel/i2c.rs

···
 /// An adapter for the registration of I2C drivers.
 pub struct Adapter<T: Driver>(T);
 
-// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
+// SAFETY:
+// - `bindings::i2c_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
+// - `struct i2c_driver` embeds a `struct device_driver`.
+// - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
+unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+    type DriverType = bindings::i2c_driver;
+    type DriverData = T;
+    const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
+}
+
+// SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
 unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
-    type RegType = bindings::i2c_driver;
-
     unsafe fn register(
-        idrv: &Opaque<Self::RegType>,
+        idrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result {
···
             (*idrv.get()).driver.acpi_match_table = acpi_table;
         }
 
-        // SAFETY: `idrv` is guaranteed to be a valid `RegType`.
+        // SAFETY: `idrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe { bindings::i2c_register_driver(module.0, idrv.get()) })
     }
 
-    unsafe fn unregister(idrv: &Opaque<Self::RegType>) {
-        // SAFETY: `idrv` is guaranteed to be a valid `RegType`.
+    unsafe fn unregister(idrv: &Opaque<Self::DriverType>) {
+        // SAFETY: `idrv` is guaranteed to be a valid `DriverType`.
         unsafe { bindings::i2c_del_driver(idrv.get()) }
     }
 }
···
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `I2cClient::set_drvdata()` has been called
         // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { idev.as_ref().drvdata_obtain::<T>() };
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T>() };
 
-        T::unbind(idev, data.as_ref());
+        T::unbind(idev, data);
     }
 
     extern "C" fn shutdown_callback(idev: *mut bindings::i2c_client) {
···
         // SAFETY: `shutdown_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>>`.
-        let data = unsafe { idev.as_ref().drvdata_obtain::<T>() };
+        let data = unsafe { idev.as_ref().drvdata_borrow::<T>() };
 
-        T::shutdown(idev, data.as_ref());
+        T::shutdown(idev, data);
     }
 
     /// The [`i2c::IdTable`] of the corresponding driver.

rust/kernel/io.rs

···
         /// Bound checks are performed on compile time, hence if the offset is not known at compile
         /// time, the build will fail.
         $(#[$attr])*
-        #[inline]
+        // Always inline to optimize out error path of `io_addr_assert`.
+        #[inline(always)]
         pub fn $name(&self, offset: usize) -> $type_name {
             let addr = self.io_addr_assert::<$type_name>(offset);
 
···
         /// Bound checks are performed on compile time, hence if the offset is not known at compile
         /// time, the build will fail.
         $(#[$attr])*
-        #[inline]
+        // Always inline to optimize out error path of `io_addr_assert`.
+        #[inline(always)]
         pub fn $name(&self, value: $type_name, offset: usize) {
             let addr = self.io_addr_assert::<$type_name>(offset);
 
···
         self.addr().checked_add(offset).ok_or(EINVAL)
     }
 
-    #[inline]
+    // Always inline to optimize out error path of `build_assert`.
+    #[inline(always)]
     fn io_addr_assert<U>(&self, offset: usize) -> usize {
         build_assert!(Self::offset_valid::<U>(offset, SIZE));
 

rust/kernel/io/resource.rs

···
     /// Resource represents a memory region that must be ioremaped using `ioremap_np`.
     pub const IORESOURCE_MEM_NONPOSTED: Flags = Flags::new(bindings::IORESOURCE_MEM_NONPOSTED);
 
+    // Always inline to optimize out error path of `build_assert`.
+    #[inline(always)]
     const fn new(value: u32) -> Self {
         crate::build_assert!(value as u64 <= c_ulong::MAX as u64);
         Flags(value as c_ulong)

rust/kernel/irq/flags.rs

···
         self.0
     }
 
+    // Always inline to optimize out error path of `build_assert`.
+    #[inline(always)]
     const fn new(value: u32) -> Self {
         build_assert!(value as u64 <= c_ulong::MAX as u64);
         Self(value as c_ulong)

rust/kernel/pci.rs

···
 /// An adapter for the registration of PCI drivers.
 pub struct Adapter<T: Driver>(T);
 
-// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
+// SAFETY:
+// - `bindings::pci_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
+// - `struct pci_driver` embeds a `struct device_driver`.
+// - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
+unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+    type DriverType = bindings::pci_driver;
+    type DriverData = T;
+    const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
+}
+
+// SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
 unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
-    type RegType = bindings::pci_driver;
-
     unsafe fn register(
-        pdrv: &Opaque<Self::RegType>,
+        pdrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result {
···
             (*pdrv.get()).id_table = T::ID_TABLE.as_ptr();
         }
 
-        // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+        // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe {
             bindings::__pci_register_driver(pdrv.get(), module.0, name.as_char_ptr())
         })
     }
 
-    unsafe fn unregister(pdrv: &Opaque<Self::RegType>) {
-        // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+    unsafe fn unregister(pdrv: &Opaque<Self::DriverType>) {
+        // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
         unsafe { bindings::pci_unregister_driver(pdrv.get()) }
     }
 }
···
         // 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>>`.
-        let data = unsafe { pdev.as_ref().drvdata_obtain::<T>() };
+        let data = unsafe { pdev.as_ref().drvdata_borrow::<T>() };
 
-        T::unbind(pdev, data.as_ref());
+        T::unbind(pdev, data);
     }
 }
 

rust/kernel/platform.rs

···
 /// An adapter for the registration of platform drivers.
 pub struct Adapter<T: Driver>(T);
 
-// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
+// SAFETY:
+// - `bindings::platform_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
+// - `struct platform_driver` embeds a `struct device_driver`.
+// - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
+unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+    type DriverType = bindings::platform_driver;
+    type DriverData = T;
+    const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
+}
+
+// SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
 unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
-    type RegType = bindings::platform_driver;
-
     unsafe fn register(
-        pdrv: &Opaque<Self::RegType>,
+        pdrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result {
···
             (*pdrv.get()).driver.acpi_match_table = acpi_table;
         }
 
-        // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+        // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe { bindings::__platform_driver_register(pdrv.get(), module.0) })
     }
 
-    unsafe fn unregister(pdrv: &Opaque<Self::RegType>) {
-        // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+    unsafe fn unregister(pdrv: &Opaque<Self::DriverType>) {
+        // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
         unsafe { bindings::platform_driver_unregister(pdrv.get()) };
     }
 }
···
         // 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>>`.
-        let data = unsafe { pdev.as_ref().drvdata_obtain::<T>() };
+        let data = unsafe { pdev.as_ref().drvdata_borrow::<T>() };
 
-        T::unbind(pdev, data.as_ref());
+        T::unbind(pdev, data);
     }
 }
 

rust/kernel/usb.rs

···
 /// An adapter for the registration of USB drivers.
 pub struct Adapter<T: Driver>(T);
 
-// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
+// SAFETY:
+// - `bindings::usb_driver` is a C type declared as `repr(C)`.
+// - `T` is the type of the driver's device private data.
+// - `struct usb_driver` embeds a `struct device_driver`.
+// - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
+unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+    type DriverType = bindings::usb_driver;
+    type DriverData = T;
+    const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
+}
+
+// SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
 unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
-    type RegType = bindings::usb_driver;
-
     unsafe fn register(
-        udrv: &Opaque<Self::RegType>,
+        udrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result {
···
             (*udrv.get()).id_table = T::ID_TABLE.as_ptr();
         }
 
-        // SAFETY: `udrv` is guaranteed to be a valid `RegType`.
+        // SAFETY: `udrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe {
             bindings::usb_register_driver(udrv.get(), module.0, name.as_char_ptr())
         })
     }
 
-    unsafe fn unregister(udrv: &Opaque<Self::RegType>) {
-        // SAFETY: `udrv` is guaranteed to be a valid `RegType`.
+    unsafe fn unregister(udrv: &Opaque<Self::DriverType>) {
+        // SAFETY: `udrv` is guaranteed to be a valid `DriverType`.
         unsafe { bindings::usb_deregister(udrv.get()) };
     }
 }
···
         // 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>>`.
-        let data = unsafe { dev.drvdata_obtain::<T>() };
+        let data = unsafe { dev.drvdata_borrow::<T>() };
 
-        T::disconnect(intf, data.as_ref());
+        T::disconnect(intf, data);
     }
 }