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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAJ-ks9=3y9EOjyDfAj6Rx9YUg-vGvm=SrPi2XGOa9Okt5hh6ug@mail.gmail.com>
Date: Wed, 15 Jan 2025 19:21:02 -0500
From: Tamir Duberstein <tamird@...il.com>
To: Andreas Hindborg <a.hindborg@...nel.org>
Cc: 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>, 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
Subject: Re: [PATCH v6 05/14] rust: hrtimer: allow timer restart from timer handler

On Wed, Jan 15, 2025 at 6:21 AM Andreas Hindborg <a.hindborg@...nel.org> wrote:
>
> "Tamir Duberstein" <tamird@...il.com> writes:
>
> > On Fri, Jan 10, 2025 at 3:17 PM Andreas Hindborg <a.hindborg@...nel.org> wrote:
> >>
> >> 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,
> >> +        }
> >> +    }
> >> +}
> >
> > These are for converting from bindings to our enum, right? Why do we
> > need both signed and unsigned,
>
> Depending on kernel (target arch) configuration, the enum type will be
> either signed or unsigned on C side.
>
> I guess I could try to figure out what kernel configs effect the change
> and then do conditional compilation on Rust side, but it seems overkill.

The bindings seem to contain a type alias:

pub const hrtimer_restart_HRTIMER_NORESTART: hrtimer_restart = 0;
pub const hrtimer_restart_HRTIMER_RESTART: hrtimer_restart = 1;
pub type hrtimer_restart = ffi::c_uint;

Perhaps you could impl `From<bindings:: hrtimer_restart>` instead?

Tamir