Re: [PATCH v7 3/6] rust: irq: add support for non-threaded IRQs and handlers

[Daniel Almeida <daniel.almeida@collabora.com>]

Hi Boqun,

[…]

>> +        IrqRequest { dev, irq }
>> +    }
>> +
>> +    /// Returns the IRQ number of an [`IrqRequest`].
>> +    pub fn irq(&self) -> u32 {
>> +        self.irq
>> +    }
>> +}
>> +
>> +/// A registration of an IRQ handler for a given IRQ line.
>> +///
>> +/// # Examples
>> +///
>> +/// The following is an example of using `Registration`. It uses a
>> +/// [`AtomicU32`](core::sync::AtomicU32) to provide the interior mutability.
> 
> We are going to remove all usage of core::sync::Atomic* when the LKMM
> atomics [1] land. You can probably use `Completion` here (handler does
> complete_all(), and registration uses wait_for_completion()) because
> `Completion` is irq-safe. And this brings my next comment..

How are completions equivalent to atomics? I am trying to highlight interior
mutability in this example.

Is the LKMM atomic series getting merged during the upcoming merge window? Because my
understanding was that the IRQ series was ready to go in 6.17, pending a reply
from Thomas and some minor comments that have been mentioned in v7.

If the LKMM series is not ready yet, my proposal is to leave the
Atomics->Completion change for a future patch (or really, to just use the new
Atomic types introduced by your series, because again, I don't think Completion
is the right thing to have there).


— Daniel