Re: [PATCH v11 04/13] rust: hrtimer: allow timer restart from timer handler

From: Lyude Paul
Date: Tue Mar 11 2025 - 13:10:45 EST


Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>

On Fri, 2025-03-07 at 22:38 +0100, Andreas Hindborg wrote:
> Allow timer handlers to report that they want a timer to be restarted after
> the timer handler has finished executing.
>
> Acked-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
> Reviewed-by: Benno Lossin <benno.lossin@xxxxxxxxx>
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
> ---
> rust/kernel/time/hrtimer.rs | 18 +++++++++++++++++-
> rust/kernel/time/hrtimer/arc.rs | 4 +---
> 2 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
> index f69a8483d21f..1a2d05ae7f21 100644
> --- a/rust/kernel/time/hrtimer.rs
> +++ b/rust/kernel/time/hrtimer.rs
> @@ -212,7 +212,7 @@ pub trait HrTimerCallback {
> type Pointer<'a>: RawHrTimerCallback;
>
> /// Called by the timer logic when the timer fires.
> - fn run(this: <Self::Pointer<'_> as RawHrTimerCallback>::CallbackTarget<'_>)
> + fn run(this: <Self::Pointer<'_> as RawHrTimerCallback>::CallbackTarget<'_>) -> HrTimerRestart
> where
> Self: Sized;
> }
> @@ -311,6 +311,22 @@ unsafe fn start(this: *const Self, expires: Ktime) {
> }
> }
>
> +/// Restart policy for timers.
> +#[derive(Copy, Clone, PartialEq, Eq, Debug)]
> +#[repr(u32)]
> +pub enum HrTimerRestart {
> + /// Timer should not be restarted.
> + NoRestart = bindings::hrtimer_restart_HRTIMER_NORESTART,
> + /// Timer should be restarted.
> + Restart = bindings::hrtimer_restart_HRTIMER_RESTART,
> +}
> +
> +impl HrTimerRestart {
> + fn into_c(self) -> bindings::hrtimer_restart {
> + self as bindings::hrtimer_restart
> + }
> +}
> +
> /// Use to implement the [`HasHrTimer<T>`] trait.
> ///
> /// See [`module`] documentation for an example.
> diff --git a/rust/kernel/time/hrtimer/arc.rs b/rust/kernel/time/hrtimer/arc.rs
> index fe3cb869bc9b..e149bd4db509 100644
> --- a/rust/kernel/time/hrtimer/arc.rs
> +++ b/rust/kernel/time/hrtimer/arc.rs
> @@ -95,8 +95,6 @@ impl<T> RawHrTimerCallback for Arc<T>
> // allocation from other `Arc` clones.
> let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
>
> - T::run(receiver);
> -
> - bindings::hrtimer_restart_HRTIMER_NORESTART
> + T::run(receiver).into_c()
> }
> }
>

--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat

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