Re: [PATCH v4 4/6] rust: irq: add support for threaded IRQs and handlers

[Danilo Krummrich <dakr@kernel.org>]

On Mon, Jun 16, 2025 at 10:48:37AM -0300, Daniel Almeida wrote:
> Hi Danilo,
> 
> > On 9 Jun 2025, at 13:24, Daniel Almeida <daniel.almeida@collabora.com> wrote:
> > 
> > Hi Danilo,
> > 
> >> On 9 Jun 2025, at 09:27, Danilo Krummrich <dakr@kernel.org> wrote:
> >> 
> >> On Sun, Jun 08, 2025 at 07:51:09PM -0300, Daniel Almeida wrote:
> >>> +/// Callbacks for a threaded IRQ handler.
> >>> +pub trait ThreadedHandler: Sync {
> >>> +    /// The actual handler function. As usual, sleeps are not allowed in IRQ
> >>> +    /// context.
> >>> +    fn handle_irq(&self) -> ThreadedIrqReturn;
> >>> +
> >>> +    /// The threaded handler function. This function is called from the irq
> >>> +    /// handler thread, which is automatically created by the system.
> >>> +    fn thread_fn(&self) -> IrqReturn;
> >>> +}
> >>> +
> >>> +impl<T: ?Sized + ThreadedHandler + Send> ThreadedHandler for Arc<T> {
> >>> +    fn handle_irq(&self) -> ThreadedIrqReturn {
> >>> +        T::handle_irq(self)
> >>> +    }
> >>> +
> >>> +    fn thread_fn(&self) -> IrqReturn {
> >>> +        T::thread_fn(self)
> >>> +    }
> >>> +}
> >> 
> >> In case you intend to be consistent with the function pointer names in
> >> request_threaded_irq(), it'd need to be handler() and thread_fn(). But I don't
> >> think there's a need for that, both aren't really nice for names of trait
> >> methods.
> >> 
> >> What about irq::Handler::handle() and irq::Handler::handle_threaded() for
> >> instance?
> >> 
> >> Alternatively, why not just
> >> 
> >> trait Handler {
> >>  fn handle(&self);
> >> }
> >> 
> >> trait ThreadedHandler {
> >>  fn handle(&self);
> >> }
> >> 
> >> and then we ask for `T: Handler + ThreadedHandler`.
> > 
> > Sure, I am totally OK with renaming things, but IIRC I've tried  Handler +
> > ThreadedHandler in the past and found it to be problematic. I don't recall why,
> > though, so maybe it's worth another attempt.
> 
> Handler::handle() returns IrqReturn and ThreadedHandler::handle() returns
> ThreadedIrqReturn, which includes WakeThread, so these had to be separate
> traits.

Ok, that fine then. But I'd still prefer the better naming as mentioned above.