linux-kernel - [PATCH v9 04/13] rust: hrtimer: allow timer restart from timer handler

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Message-Id: <20250224-hrtimer-v3-v6-12-rc2-v9-4-5bd3bf0ce6cc@kernel.org>
Date: Mon, 24 Feb 2025 13:03:38 +0100
From: Andreas Hindborg <a.hindborg@...nel.org>
To: Miguel Ojeda <ojeda@...nel.org>, 
 Anna-Maria Behnsen <anna-maria@...utronix.de>, 
 Frederic Weisbecker <frederic@...nel.org>, 
 Thomas Gleixner <tglx@...utronix.de>, Danilo Krummrich <dakr@...nel.org>
Cc: Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, 
 Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <benno.lossin@...ton.me>, Alice Ryhl <aliceryhl@...gle.com>, 
 Trevor Gross <tmgross@...ch.edu>, Lyude Paul <lyude@...hat.com>, 
 Guangbo Cui <2407018371@...com>, Dirk Behme <dirk.behme@...il.com>, 
 Daniel Almeida <daniel.almeida@...labora.com>, 
 Tamir Duberstein <tamird@...il.com>, rust-for-linux@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Andreas Hindborg <a.hindborg@...nel.org>
Subject: [PATCH v9 04/13] rust: hrtimer: allow timer restart from timer
 handler

This patch allows timer handlers to report that they want a timer to be
restarted after the timer handler has finished executing.

Also update the `hrtimer` documentation to showcase the new feature.

Acked-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
---
 rust/kernel/time/hrtimer.rs     | 19 ++++++++++++++++++-
 rust/kernel/time/hrtimer/arc.rs |  4 +---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
index d08fd7de158d..a431c8b728ae 100644
--- a/rust/kernel/time/hrtimer.rs
+++ b/rust/kernel/time/hrtimer.rs
@@ -207,7 +207,7 @@ 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;
 }
@@ -313,6 +313,23 @@ unsafe fn start(self_ptr: *const Self, expires: Ktime) {
     }
 }
 
+/// Restart policy for timers.
+pub enum HrTimerRestart {
+    /// Timer should not be restarted.
+    NoRestart,
+    /// Timer should be restarted.
+    Restart,
+}
+
+impl HrTimerRestart {
+    fn into_c(self) -> bindings::hrtimer_restart {
+        match self {
+            HrTimerRestart::NoRestart => bindings::hrtimer_restart_HRTIMER_NORESTART,
+            HrTimerRestart::Restart => bindings::hrtimer_restart_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 5c916489fc13..7152fa414b37 100644
--- a/rust/kernel/time/hrtimer/arc.rs
+++ b/rust/kernel/time/hrtimer/arc.rs
@@ -87,8 +87,6 @@ impl<T> RawHrTimerCallback for Arc<T>
         // timer. This `T` is contained in an `Arc`.
         let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
 
-        T::run(receiver);
-
-        bindings::hrtimer_restart_HRTIMER_NORESTART
+        T::run(receiver).into_c()
     }
 }

-- 
2.47.0