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rust: device: implement impl_device_context_deref!

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The Deref hierarchy for device context generics is the same for every
(bus specific) device.

Implement those with a generic macro to avoid duplicated boiler plate
code and ensure the correct Deref hierarchy for every device
implementation.

Co-developed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Christian Schrefl <chrisi.schrefl@gmail.com>
Link: https://lore.kernel.org/r/20250413173758.12068-2-dakr@kernel.org
[ Add missing `::` prefix in macros. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Danilo Krummrich
2025-04-13 19:36:56 +02:00
parent 0af2f6be1b
commit cb271c2edf
3 changed files with 50 additions and 27 deletions
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44
rust/kernel/device.rs
View File

@@ -235,6 +235,50 @@ mod private {
impl DeviceContext for Core {}
impl DeviceContext for Normal {}
/// # Safety
///
/// The type given as `$device` must be a transparent wrapper of a type that doesn't depend on the
/// generic argument of `$device`.
#[doc(hidden)]
#[macro_export]
macro_rules! __impl_device_context_deref {
(unsafe { $device:ident, $src:ty => $dst:ty }) => {
impl ::core::ops::Deref for $device<$src> {
type Target = $device<$dst>;
fn deref(&self) -> &Self::Target {
let ptr: *const Self = self;
// CAST: `$device<$src>` and `$device<$dst>` transparently wrap the same type by the
// safety requirement of the macro.
let ptr = ptr.cast::<Self::Target>();
// SAFETY: `ptr` was derived from `&self`.
unsafe { &*ptr }
}
}
};
}
/// Implement [`core::ops::Deref`] traits for allowed [`DeviceContext`] conversions of a (bus
/// specific) device.
///
/// # Safety
///
/// The type given as `$device` must be a transparent wrapper of a type that doesn't depend on the
/// generic argument of `$device`.
#[macro_export]
macro_rules! impl_device_context_deref {
(unsafe { $device:ident }) => {
// SAFETY: This macro has the exact same safety requirement as
// `__impl_device_context_deref!`.
::kernel::__impl_device_context_deref!(unsafe {
$device,
$crate::device::Core => $crate::device::Normal
});
};
}
#[doc(hidden)]
#[macro_export]
macro_rules! dev_printk {

16
rust/kernel/pci.rs
View File

@@ -422,19 +422,9 @@ impl Device<device::Core> {
}
}
impl Deref for Device<device::Core> {
type Target = Device;
fn deref(&self) -> &Self::Target {
let ptr: *const Self = self;
// CAST: `Device<Ctx>` is a transparent wrapper of `Opaque<bindings::pci_dev>`.
let ptr = ptr.cast::<Device>();
// SAFETY: `ptr` was derived from `&self`.
unsafe { &*ptr }
}
}
// SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
// argument.
kernel::impl_device_context_deref!(unsafe { Device });
impl From<&Device<device::Core>> for ARef<Device> {
fn from(dev: &Device<device::Core>) -> Self {

17
rust/kernel/platform.rs
View File

@@ -16,7 +16,6 @@ use crate::{
use core::{
marker::PhantomData,
ops::Deref,
ptr::{addr_of_mut, NonNull},
};
@@ -190,19 +189,9 @@ impl Device {
}
}
impl Deref for Device<device::Core> {
type Target = Device;
fn deref(&self) -> &Self::Target {
let ptr: *const Self = self;
// CAST: `Device<Ctx>` is a transparent wrapper of `Opaque<bindings::platform_device>`.
let ptr = ptr.cast::<Device>();
// SAFETY: `ptr` was derived from `&self`.
unsafe { &*ptr }
}
}
// SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
// argument.
kernel::impl_device_context_deref!(unsafe { Device });
impl From<&Device<device::Core>> for ARef<Device> {
fn from(dev: &Device<device::Core>) -> Self {