Commit cb271c2e authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

rust: device: implement impl_device_context_deref! 



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: default avatarBenno Lossin <benno.lossin@proton.me>
Signed-off-by: default avatarBenno Lossin <benno.lossin@proton.me>
Reviewed-by: default avatarChristian 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: default avatarDanilo Krummrich <dakr@kernel.org>
parent 0af2f6be

rust/kernel/device.rs

+44 −0
Original line number Diff line number Diff line
@@ -235,6 +235,50 @@ impl Sealed for super::Normal {} 
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 {

rust/kernel/pci.rs

+3 −13
Original line number Diff line number Diff line
@@ -422,19 +422,9 @@ pub fn set_master(&self) { 
    }

}



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 {

rust/kernel/platform.rs

+3 −14
Original line number Diff line number Diff line
@@ -16,7 +16,6 @@ 


use core::{

    marker::PhantomData,

    ops::Deref,

    ptr::{addr_of_mut, NonNull},

};
@@ -190,19 +189,9 @@ fn as_raw(&self) -> *mut bindings::platform_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 {