netdev - Re: [net-next PATCH v10 7/7] rust: net::phy sync with match_phy

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Message-Id: <20250516.213005.1257508224493103119.fujita.tomonori@gmail.com>
Date: Fri, 16 May 2025 21:30:05 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: ansuelsmth@...il.com
Cc: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
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Subject: Re: [net-next PATCH v10 7/7] rust: net::phy sync with
 match_phy_device C changes

Hi,

On Thu, 15 May 2025 13:27:12 +0200
Christian Marangi <ansuelsmth@...il.com> wrote:

> Sync match_phy_device callback wrapper in net:phy rust with the C
> changes where match_phy_device also provide the passed PHY driver.
> 
> As explained in the C commit, this is useful for match_phy_device to
> access the PHY ID defined in the PHY driver permitting more generalized
> functions.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> ---
>  rust/kernel/net/phy.rs | 26 +++++++++++++++++++++++---
>  1 file changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs
> index a59469c785e3..936a137a8a29 100644
> --- a/rust/kernel/net/phy.rs
> +++ b/rust/kernel/net/phy.rs
> @@ -418,15 +418,18 @@ impl<T: Driver> Adapter<T> {
>  
>      /// # Safety
>      ///
> -    /// `phydev` must be passed by the corresponding callback in `phy_driver`.
> +    /// `phydev` and `phydrv` must be passed by the corresponding callback in
> +    //  `phy_driver`.
>      unsafe extern "C" fn match_phy_device_callback(
>          phydev: *mut bindings::phy_device,
> +        phydrv: *const bindings::phy_driver
>      ) -> crate::ffi::c_int {
>          // SAFETY: This callback is called only in contexts
>          // where we hold `phy_device->lock`, so the accessors on
>          // `Device` are okay to call.
>          let dev = unsafe { Device::from_raw(phydev) };
> -        T::match_phy_device(dev) as i32
> +        let drv = unsafe { T::from_raw(phydrv) };
> +        T::match_phy_device(dev, drv) as i32
>      }
>  
>      /// # Safety
> @@ -574,6 +577,23 @@ pub const fn create_phy_driver<T: Driver>() -> DriverVTable {
>  /// This trait is used to create a [`DriverVTable`].
>  #[vtable]
>  pub trait Driver {
> +    /// # Safety
> +    ///
> +    /// For the duration of `'a`,
> +    /// - the pointer must point at a valid `phy_driver`, and the caller
> +    ///   must be in a context where all methods defined on this struct
> +    ///   are safe to call.
> +    unsafe fn from_raw<'a>(ptr: *const bindings::phy_driver) -> &'a Self
> +    where
> +        Self: Sized,
> +    {
> +        // CAST: `Self` is a `repr(transparent)` wrapper around `bindings::phy_driver`.
> +        let ptr = ptr.cast::<Self>();
> +        // SAFETY: by the function requirements the pointer is valid and we have unique access for
> +        // the duration of `'a`.
> +        unsafe { &*ptr }
> +    }

We might need to update the comment. phy_driver is const so I think
that we can access to it any time.

>      /// Defines certain other features this PHY supports.
>      /// It is a combination of the flags in the [`flags`] module.
>      const FLAGS: u32 = 0;
> @@ -602,7 +622,7 @@ fn get_features(_dev: &mut Device) -> Result {
>  
>      /// Returns true if this is a suitable driver for the given phydev.
>      /// If not implemented, matching is based on [`Driver::PHY_DEVICE_ID`].
> -    fn match_phy_device(_dev: &Device) -> bool {
> +    fn match_phy_device<T: Driver>(_dev: &mut Device, _drv: &T) -> bool {
>          false
>      }

I think that it could be a bit simpler:

fn match_phy_device(_dev: &mut Device, _drv: &Self) -> bool

Or making it a trait method might be more idiomatic?

fn match_phy_device(&self, _dev: &mut Device) -> bool


Thanks!