linux-kernel - Re: [PATCH v8 01/14] rust: time: Add Ktime::from

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Message-ID: <693e39f6-70ac-4752-b371-74a3bd1fcf16@proton.me>
Date: Wed, 19 Feb 2025 11:58:11 +0000
From: Benno Lossin <benno.lossin@...ton.me>
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>, 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
Subject: Re: [PATCH v8 01/14] rust: time: Add Ktime::from_ns()

On 18.02.25 14:27, Andreas Hindborg wrote:
> From: Lyude Paul <lyude@...hat.com>
> 
> A simple function to turn the provided value in nanoseconds into a Ktime
> value. We allow any type which implements Into<bindings::ktime_t>, which
> resolves to Into<i64>.
> 
> This is useful for some of the older DRM APIs that never got moved to
> Ktime.

Are these older DRM APIs on the C side, or on the Rust side? If they are
on the Rust side, we should just move them to Ktime, no?

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

This seems wrong considering the `From Lyude Paul` line above :) (or is
it possible to review your own patch?)

The patch itself looks good, so iff the above question is answered with
"the older DRM APIs are on the C side" then:

Reviewed-by: Benno Lossin <benno.lossin@...ton.me>

---
Cheers,
Benno

> Signed-off-by: Andreas Hindborg <a.hindborg@...nel.org>
> ---
>  rust/kernel/time.rs | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
> index 379c0f5772e57..87e47f2f5618d 100644
> --- a/rust/kernel/time.rs
> +++ b/rust/kernel/time.rs
> @@ -8,6 +8,8 @@
>  //! C header: [`include/linux/jiffies.h`](srctree/include/linux/jiffies.h).
>  //! C header: [`include/linux/ktime.h`](srctree/include/linux/ktime.h).
> 
> +use core::convert::Into;
> +
>  /// The number of nanoseconds per millisecond.
>  pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64;
> 
> @@ -63,6 +65,12 @@ pub fn to_ns(self) -> i64 {
>      pub fn to_ms(self) -> i64 {
>          self.divns_constant::<NSEC_PER_MSEC>()
>      }
> +
> +    /// Creates a new Ktime from the given duration in nanoseconds.
> +    #[inline]
> +    pub fn from_nanos(ns: impl Into<bindings::ktime_t>) -> Self {
> +        Self { inner: ns.into() }
> +    }
>  }
> 
>  /// Returns the number of milliseconds between two ktimes.
> 
> --
> 2.47.0
> 
>