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

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Message-ID: <68275555.050a0220.337522.0bff@mx.google.com>
Date: Fri, 16 May 2025 17:10:08 +0200
From: Christian Marangi <ansuelsmth@...il.com>
To: FUJITA Tomonori <fujita.tomonori@...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

On Fri, May 16, 2025 at 09:30:05PM +0900, FUJITA Tomonori wrote:
> 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.
>

Any hint for a better comment?

> >      /// 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!

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