linux-kernel - [PATCH v6 05/14] rust: hrtimer: allow timer restart from timer handler

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Message-Id: <20250110-hrtimer-v3-v6-12-rc2-v6-5-f71d50f16482@kernel.org>
Date: Fri, 10 Jan 2025 21:15:28 +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>, 
 rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Andreas Hindborg <a.hindborg@...nel.org>
Subject: [PATCH v6 05/14] 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.

Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
---
 rust/kernel/time/hrtimer.rs     | 37 ++++++++++++++++++++++++++++++++++++-
 rust/kernel/time/hrtimer/arc.rs |  4 +---
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
index d0842c7c4c6ddffeef9a79cbf9727819060e4333..50e8c23578b5cf7196893ac88d9547fc027f1f04 100644
--- a/rust/kernel/time/hrtimer.rs
+++ b/rust/kernel/time/hrtimer.rs
@@ -167,7 +167,7 @@ pub trait HrTimerCallback {
     type CallbackTargetParameter<'a>;
 
     /// Called by the timer logic when the timer fires.
-    fn run(this: Self::CallbackTargetParameter<'_>)
+    fn run(this: Self::CallbackTargetParameter<'_>) -> HrTimerRestart
     where
         Self: Sized;
 }
@@ -262,6 +262,41 @@ 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 From<u32> for HrTimerRestart {
+    fn from(value: u32) -> Self {
+        match value {
+            0 => Self::NoRestart,
+            _ => Self::Restart,
+        }
+    }
+}
+
+impl From<i32> for HrTimerRestart {
+    fn from(value: i32) -> Self {
+        match value {
+            0 => Self::NoRestart,
+            _ => Self::Restart,
+        }
+    }
+}
+
+impl From<HrTimerRestart> for bindings::hrtimer_restart {
+    fn from(value: HrTimerRestart) -> Self {
+        match value {
+            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 4c1812f190bc7a9e0b2fcd5ea2e320f45ba584bc..cee143b04aa21fa6c60c3363cd95f7a67360cbf8 100644
--- a/rust/kernel/time/hrtimer/arc.rs
+++ b/rust/kernel/time/hrtimer/arc.rs
@@ -82,8 +82,6 @@ impl<U> RawHrTimerCallback for Arc<U>
         // timer. This `U` is contained in an `Arc`.
         let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
 
-        U::run(receiver);
-
-        bindings::hrtimer_restart_HRTIMER_NORESTART
+        U::run(receiver).into()
     }
 }

-- 
2.47.0