Re: [PATCH v3 1/2] rust: irq: add support for request_irq()

["Benno Lossin" <lossin@kernel.org>]

On Sun May 18, 2025 at 3:24 PM CEST, Alexandre Courbot wrote:
> Hi Daniel,
>
> On Thu May 15, 2025 at 4:20 AM JST, Daniel Almeida wrote:
> <snip>
>> +/// Callbacks for an IRQ handler.
>> +pub trait Handler: Sync {
>> +    /// The actual handler function. As usual, sleeps are not allowed in IRQ
>> +    /// context.
>> +    fn handle_irq(&self) -> IrqReturn;
>> +}
>> +
>> +impl<T: ?Sized + Handler + Send> Handler for Arc<T> {
>> +    fn handle_irq(&self) -> IrqReturn {
>> +        T::handle_irq(self)
>> +    }
>> +}
>> +
>> +impl<T: ?Sized + Handler, A: Allocator> Handler for Box<T, A> {
>> +    fn handle_irq(&self) -> IrqReturn {
>> +        T::handle_irq(self)
>> +    }
>> +}
>
> I see that every smart pointer would have to implement Handler in order
> to be used with this module, but...
>
>> +#[pin_data(PinnedDrop)]
>> +pub struct Registration<T: Handler> {
>> +    irq: u32,
>> +    #[pin]
>> +    handler: T,
>
> ... what if you store another type `U: Borrow<T>` here, and take it as
> the argument of `register`? This way you should be able to use anything
> that implements Borrow<T>, which includes T itself, Arc<T>, Box<T>, and
> more, and can remove the two impl blocks above.

I don't think that this is easily possible, since then the
`Registration` struct will have two generics, which I think is worse.

The impls above are pretty common for these kinds of traits, so I don't
think it's too bad.

---
Cheers,
Benno