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@kernel.org>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
 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 c6d6eaed31aa..78afb093aee8 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;
 }
@@ -312,6 +312,22 @@ 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 df97fade0aa1..4a984d85b4a1 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()
     }
 }

-- 
2.47.0

On Sun, Mar 9, 2025 at 11:22 AM Andreas Hindborg <a.hindborg@kernel.org> 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@kernel.org>
> Reviewed-by: Benno Lossin <benno.lossin@proton.me>
> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
> ---
>  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 c6d6eaed31aa..78afb093aee8 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;
>  }
> @@ -312,6 +312,22 @@ 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,
> +}

Instead of writing this enum by hand, could we use the
`--rustified-enum` option to bindgen? I added `--rustified-enum
hrtimer_restart` in `rust/bindgen_parameters` and the result was

#[repr(u32)]
#[derive(Copy, Clone, Hash, PartialEq, Eq)]
pub enum hrtimer_restart {
    HRTIMER_NORESTART = 0,
    HRTIMER_RESTART = 1,
}

what do you think? This can be revisited, so either way:

Reviewed-by: Tamir Duberstein <tamird@gmail.com>