Re: [PATCH net-next v7 1/5] rust: core abstractions for network PHY drivers

Boqun Feng
2023-10-27T20:00:43Z

On Thu, Oct 26, 2023 at 09:10:46AM +0900, FUJITA Tomonori wrote:
[...]
> + /// Gets the current link state.
> + ///
> + /// It returns true if the link is up.
> + pub fn is_link_up(&self) -> bool {
> + const LINK_IS_UP: u32 = 1;
> + // SAFETY: `phydev` is pointing to a valid object by the type invariant of `Self`.
> + let phydev = unsafe { *self.0.get() };

Tomo, FWIW, the above line means *copying* the content pointed by
`self.0.get()` into `phydev`, i.e. `phydev` is the semantically a copy
of the `phy_device` instead of an alias. In C code, it means you did:

struct phy_device phydev = *ptr;

Sure, both compilers can figure this out, therefore no extra copy is
done, but still it's better to avoid this copy semantics by doing:

let phydev = unsafe { &*self.0.get() };

it's equal to C code:

struct phy_device *phydev = ptr;

Ditto for is_autoneg_enabled() and is_autoneg_completed().

Regards,
Boqun

> + phydev.link() == LINK_IS_UP
> + }
> +
> + /// Gets the current auto-negotiation configuration.
> + ///
> + /// It returns true if auto-negotiation is enabled.
> + pub fn is_autoneg_enabled(&self) -> bool {
> + // SAFETY: `phydev` is pointing to a valid object by the type invariant of `Self`.
> + let phydev = unsafe { *self.0.get() };
> + phydev.autoneg() == bindings::AUTONEG_ENABLE
> + }
> +
> + /// Gets the current auto-negotiation state.
> + ///
> + /// It returns true if auto-negotiation is completed.
> + pub fn is_autoneg_completed(&self) -> bool {
> + const AUTONEG_COMPLETED: u32 = 1;
> + // SAFETY: `phydev` is pointing to a valid object by the type invariant of `Self`.
> + let phydev = unsafe { *self.0.get() };
> + phydev.autoneg_complete() == AUTONEG_COMPLETED
> + } …