Message-ID: <a285c9ead1474a98770b1c0a812f2e762c178bc6.camel@redhat.com>
Date: Mon, 24 Feb 2025 18:42:36 -0500
From: Lyude Paul <lyude@...hat.com>
To: Andreas Hindborg <a.hindborg@...nel.org>, 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>,  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
Subject: Re: [PATCH v9 12/13] rust: hrtimer: add clocksource selection
 through `ClockSource`

Same question about repr(u32) here, but with that resolved:

Reviewed-by: Lyude Paul <lyude@...hat.com>

On Mon, 2025-02-24 at 13:03 +0100, Andreas Hindborg wrote:
> Allow selecting a clock source for timers by passing a `ClockSource`
> variant to `HrTimer::new`.
> 
> Acked-by: Frederic Weisbecker <frederic@...nel.org>
> Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
> ---
>  rust/kernel/time/hrtimer.rs | 59 +++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 57 insertions(+), 2 deletions(-)
> 
> diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
> index 160df73a2d44..77b8748ec29f 100644
> --- a/rust/kernel/time/hrtimer.rs
> +++ b/rust/kernel/time/hrtimer.rs
> @@ -93,7 +93,7 @@ unsafe impl<T> Sync for HrTimer<T> {}
>  
>  impl<T> HrTimer<T> {
>      /// Return an initializer for a new timer instance.
> -    pub fn new(mode: HrTimerMode) -> impl PinInit<Self>
> +    pub fn new(mode: HrTimerMode, clock: ClockSource) -> impl PinInit<Self>
>      where
>          T: HrTimerCallback,
>      {
> @@ -107,7 +107,7 @@ pub fn new(mode: HrTimerMode) -> impl PinInit<Self>
>                      bindings::hrtimer_setup(
>                          place,
>                          Some(T::Pointer::run),
> -                        bindings::CLOCK_MONOTONIC as i32,
> +                        clock.into_c(),
>                          mode.into_c(),
>                      );
>                  }
> @@ -468,6 +468,61 @@ fn into_c(self) -> bindings::hrtimer_mode {
>      }
>  }
>  
> +/// The clock source to use for a [`HrTimer`].
> +pub enum ClockSource {
> +    /// A settable system-wide clock that measures real (i.e., wall-clock) time.
> +    ///
> +    /// Setting this clock requires appropriate privileges. This clock is
> +    /// affected by discontinuous jumps in the system time (e.g., if the system
> +    /// administrator manually changes the clock), and by frequency adjustments
> +    /// performed by NTP and similar applications via adjtime(3), adjtimex(2),
> +    /// clock_adjtime(2), and ntp_adjtime(3). This clock normally counts the
> +    /// number of seconds since 1970-01-01 00:00:00 Coordinated Universal Time
> +    /// (UTC) except that it ignores leap seconds; near a leap second it is
> +    /// typically adjusted by NTP to stay roughly in sync with UTC.
> +    RealTime,
> +    /// A monotonically increasing clock.
> +    ///
> +    /// A nonsettable system-wide clock that represents monotonic time since—as
> +    /// described by POSIX—"some unspecified point in the past". On Linux, that
> +    /// point corresponds to the number of seconds that the system has been
> +    /// running since it was booted.
> +    ///
> +    /// The CLOCK_MONOTONIC clock is not affected by discontinuous jumps in the
> +    /// system time (e.g., if the system administrator manually changes the
> +    /// clock), but is affected by frequency adjustments. This clock does not
> +    /// count time that the system is suspended.
> +    Monotonic,
> +    /// A monotonic that ticks while system is suspended.
> +    ///
> +    /// A nonsettable system-wide clock that is identical to CLOCK_MONOTONIC,
> +    /// except that it also includes any time that the system is suspended. This
> +    /// allows applications to get a suspend-aware monotonic clock without
> +    /// having to deal with the complications of CLOCK_REALTIME, which may have
> +    /// discontinuities if the time is changed using settimeofday(2) or similar.
> +    BootTime,
> +    /// International Atomic Time.
> +    ///
> +    /// A nonsettable system-wide clock derived from wall-clock time but
> +    /// counting leap seconds. This clock does not experience discontinuities or
> +    /// frequency adjustments caused by inserting leap seconds as CLOCK_REALTIME
> +    /// does.
> +    ///
> +    /// The acronym TAI refers to International Atomic Time.
> +    TAI,
> +}
> +
> +impl ClockSource {
> +    fn into_c(self) -> bindings::clockid_t {
> +        match self {
> +            ClockSource::RealTime => bindings::CLOCK_REALTIME as i32,
> +            ClockSource::Monotonic => bindings::CLOCK_MONOTONIC as i32,
> +            ClockSource::BootTime => bindings::CLOCK_BOOTTIME as i32,
> +            ClockSource::TAI => bindings::CLOCK_TAI as i32,
> +        }
> +    }
> +}
> +
>  /// Use to implement the [`HasHrTimer<T>`] trait.
>  ///
>  /// See [`module`] documentation for an example.
> 

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

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