Re: [PATCH 4/6] rust: hrtimer: restrict expires() to exclusive access

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The newly introduced `expires_unchecked` method is private, making it inaccessible outside the module and defeating its documented purpose.
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--- Patch [4]: [PATCH 4/6] rust: hrtimer: restrict expires() to exclusive access ---
commit eb28ef35be5861cd1df93f56841e97d8fd3ed101
Author: FUJITA Tomonori <fujita.tomonori@gmail.com>

rust: hrtimer: restrict expires() to exclusive access

This commit changes HrTimer::expires() to require exclusive access via
Pin<&mut Self> to prevent unsynchronized reads. It routes the read through
a new C helper and introduces an unsafe expires_unchecked() method for
contexts guaranteeing exclusive access externally.

Link: https://lore.kernel.org/r/20260813134834.1562995-4-tomo@flapping.org

> diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
> index e6570a6162035..bdb6aaa228396 100644
> --- a/rust/kernel/time/hrtimer.rs
> +++ b/rust/kernel/time/hrtimer.rs

[ ... ]

> @@ -567,27 +567,36 @@ pub fn forward_now(self: Pin<&mut Self>, interval: Delta) -> u64
>          self.forward(HrTimerInstant::<T>::now(), interval)
>      }
>  
> +    /// Return the time expiry for this [`HrTimer`].
> +    ///
> +    /// # Safety
> +    ///
> +    /// The caller must have exclusive access to `self`.
> +    #[inline]
> +    unsafe fn expires_unchecked(&self) -> HrTimerInstant<T>

[Severity: Medium]
Will this method be usable by external modules or drivers? 

The commit message states the intent is to provide expires_unchecked() for
contexts that can guarantee exclusive access by other means.

Since it is missing the pub visibility modifier, it appears to be private
to the hrtimer module and inaccessible to other Rust code that might need it.

> +    where
> +        T: HasHrTimer<T>,
> +    {
> +        // SAFETY:
> +        // - The C API requirements for this function are fulfilled by our safety contract.
> +        // - Timers cannot have negative `ktime_t` values as their expiration time.
> +        unsafe { Instant::from_ktime(bindings::hrtimer_get_expires(Self::raw_get(self))) }
> +    }

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Sashiko AI review · https://sashiko.dev/#/patchset/20260825-expires-v2-v1-0-90411c6217c7@kernel.org?part=4