Re: [PATCH v3 1/5] rust: pci: convert IrqVectorRegistration to a lifetime-managed owning type

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The lifetime linkage between `IrqVectorRegistration`, `IrqVector`, and `irq::Registration` forces a self-referential struct design, making the API unusable for device drivers.
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--- Patch [1]: [PATCH v3 1/5] rust: pci: convert IrqVectorRegistration to a lifetime-managed owning type ---
commit d29a976d8fb0d09c0565565666049353a896a317
Author: Danilo Krummrich <dakr@kernel.org>

rust: pci: convert IrqVectorRegistration to a lifetime-managed owning type

This commit converts IrqVectorRegistration to a lifetime-annotated type that
owns the PCI interrupt vector allocation. It modifies IrqVector to hold a
reference to the registration, preventing the allocation from being dropped
while vectors are still in use.

> diff --git a/rust/kernel/pci/irq.rs b/rust/kernel/pci/irq.rs
> index fea484dcf9cf2..daba86505cd2b 100644
> --- a/rust/kernel/pci/irq.rs
> +++ b/rust/kernel/pci/irq.rs
[ ... ]
> @@ -78,6 +75,7 @@ const fn as_raw(self) -> u32 {
>  #[derive(Clone, Copy)]
>  pub struct IrqVector<'a> {
>      dev: &'a Device<Bound>,
> +    reg: &'a IrqVectorRegistration<'a>,
>      index: u32,
>  }
[ ... ]
> +    pub fn index(&self, index: usize) -> Result<IrqVector<'_>> {
> +        if index >= self.len.get() {
> +            return Err(EINVAL);
> +        }
>  
> -        Ok(range)
> +        // SAFETY: index is within bounds of this registration's allocation, and self.dev is
> +        // the device it was allocated from.
> +        Ok(unsafe { IrqVector::new(self.dev, self, index as u32) })
>      }

[Severity: High]
Could this introduce a regression by creating a self-referential struct
requirement for device drivers?

A typical device driver must maintain both the IrqVectorRegistration (to keep
vectors allocated) and the irq::Registration (to keep handlers active) within
its long-lived state struct across the driver lifecycle.

Looking at IrqVectorRegistration::index() in rust/kernel/pci/irq.rs, it returns
an IrqVector tied to the local borrow of self. This lifetime dependency
propagates to irq::Registration.

Storing both objects in the same driver struct requires a self-referential
design, which cannot be safely modeled using the kernel's pin_init macro.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260813165234.620555-1-dakr@kernel.org?part=1