linux-kernel - [PATCH v1 0/5] rust: time: Convert hrtimer to use Instant and Delta

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Message-ID: <20250504045959.238068-1-fujita.tomonori@gmail.com>
Date: Sun,  4 May 2025 13:59:53 +0900
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: rust-for-linux@...r.kernel.org
Cc: a.hindborg@...nel.org,
	boqun.feng@...il.com,
	frederic@...nel.org,
	lyude@...hat.com,
	tglx@...utronix.de,
	anna-maria@...utronix.de,
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	tmgross@...ch.edu,
	dakr@...nel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v1 0/5] rust: time: Convert hrtimer to use Instant and Delta

Convert hrtimer to use `Instant` and `Delta`; remove the use of
`Ktime` from the hrtimer code, which was originally introduced as a
temporary workaround.

hrtimer uses either an `Instant` or a `Delta` as its expiration value,
depending on the mode specified at creation time. This patchset
replaces `HrTimerMode` enum with a trait-based abstraction and
associates each mode with either an `Instant` or a `Delta`. By
leveraging Rust's type system, this change enables `HrTimer` to be
statically associated with a specific `HrTimerMode`, the corresponding
`Instant` or `Delta`, and a `ClockSource`.

The `impl_has_hr_timer` macro is extended to allow specifying the
`HrTimerMode`. In the following example, it guarantees that the
`start()` method for `Foo` only accepts `Instant<Monotonic>`. Using a
`Delta` or an `Instant` with a different clock source will result in a
compile-time error:

struct Foo {
    #[pin]
    timer: HrTimer<Self>,

}

impl_has_hr_timer! {
    impl HasHrTimer<Self> for Foo {
        mode = AbsoluteMode<Monotonic>,
        self.timer
    }
}

This design eliminates runtime mismatches between expires types and
clock sources, and enables stronger type-level guarantees throughout
hrtimer.

This patchset can be applied on top of the typed clock sources patchset:

https://lore.kernel.org/lkml/20250504042436.237756-1-fujita.tomonori@gmail.com/

FUJITA Tomonori (5):
  rust: time: Change Delta methods to take &self instead of self
  rust: timer: Replace HrTimerMode enum with trait-based mode types
  rust: time: Add HrTimerExpires trait
  rust: time: Make HasHrTimer generic over HrTimerMode
  rust: time: Remove Ktime in hrtimer

 rust/kernel/time.rs                 |  15 +-
 rust/kernel/time/hrtimer.rs         | 288 ++++++++++++++++++----------
 rust/kernel/time/hrtimer/arc.rs     |   8 +-
 rust/kernel/time/hrtimer/pin.rs     |   8 +-
 rust/kernel/time/hrtimer/pin_mut.rs |   8 +-
 rust/kernel/time/hrtimer/tbox.rs    |   8 +-
 6 files changed, 225 insertions(+), 110 deletions(-)

base-commit: 7b33a2d9c12023a73b7ba105a3eed77c3527a94e
-- 
2.43.0