Re: [GIT PULL] Rust `hrtimer` support for v6.15

[Andreas Hindborg <a.hindborg@kernel.org>]

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Hi Miguel,

Andreas Hindborg <a.hindborg@kernel.org> writes:

> Hi Miguel,
>
> Please pull the Rust support for hrtimer for v6.15.
>
> This initial support allows for intrusive use of timers without
> allocating when starting a timer. We support `Pin<Box<T>>`, `Arc<T>`,
> `Pin<&T>` and `Pin<&mut T>` pointer types for working with these
> intrusive timers. We support at most one `HrTimer` field in a struct for
> use with this API.
>
> For now, the primary users will be the Rust null block driver, `rnull`,
> and the Rust kernel mode setting driver `rkvms`. I expect us to add more
> features to the API as the demands from users grow.
>
> The PR also includes two changes for the core rust and rust/alloc
> subsytems that are dependencies of the hrtimer Rust API: `Arc::as_ptr`
> and `Box::into_pin`. The alloc change was Ack'd by Danilo.
>
> The commits were in linux-next since next-20250313.

Please find an updated pull request below.

As discussed, I fixed the UB you fund in:

  rust: hrtimer: allow timer restart from timer handler

by casting to `u32` when assigning enum values. The commits below this
commit are unchanged, the later commits were replayed on top of the
changed commit.

The following changes since commit a64dcfb451e254085a7daee5fe51bf22959d52d3:

  Linux 6.14-rc2 (2025-02-09 12:45:03 -0800)

are available in the Git repository at:

  https://github.com/rust-for-linux/linux.git tags/rust-hrtimer-for-v6.15-v2

for you to fetch changes up to ac4f9157e8d7f6a9793209a693cb3e3a6f840983:

  rust: hrtimer: add maintainer entry (2025-03-21 12:56:38 +0100)


Best regards,
Andreas Hindborg


- ----------------------------------------------------------------
Rust hrtimer API for v6.15

Introduce Rust support for the `hrtimer` subsystem:

 - Add a way to use the `hrtimer` subsystem from Rust. Rust code can now set up
   intrusive timers without allocating when starting the timer.

 - Add support for `Pin<Box<_>>`, `Arc<_>`, `Pin<&_>` and `Pin<&mut _>` as
   pointer types for use with timer callbacks.

 - Add support for setting clock source and timer mode.

`kernel` crate:

 - Add `Arc::as_ptr` for converting an `Arc` to a raw pointer. This is a
   dependency for the `hrtimer` API.

 - Add `Box::into_pin` for converting a `Box<_>` into a `Pin<Box<_>>` to align
   with Rust `alloc`. This is a dependency for the `hrtimer` API.

- ----------------------------------------------------------------
Andreas Hindborg (13):
      rust: hrtimer: introduce hrtimer support
      rust: sync: add `Arc::as_ptr`
      rust: hrtimer: implement `HrTimerPointer` for `Arc`
      rust: hrtimer: allow timer restart from timer handler
      rust: hrtimer: add `UnsafeHrTimerPointer`
      rust: hrtimer: add `hrtimer::ScopedHrTimerPointer`
      rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&T>`
      rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&mut T>`
      rust: alloc: add `Box::into_pin`
      rust: hrtimer: implement `HrTimerPointer` for `Pin<Box<T>>`
      rust: hrtimer: add `HrTimerMode`
      rust: hrtimer: add clocksource selection through `ClockId`
      rust: hrtimer: add maintainer entry

 MAINTAINERS                         |  15 ++
 rust/kernel/alloc/kbox.rs           |   6 +
 rust/kernel/sync/arc.rs             |  13 +-
 rust/kernel/time.rs                 |  68 +++++
 rust/kernel/time/hrtimer.rs         | 517 ++++++++++++++++++++++++++++++++++++
 rust/kernel/time/hrtimer/arc.rs     | 100 +++++++
 rust/kernel/time/hrtimer/pin.rs     | 104 ++++++++
 rust/kernel/time/hrtimer/pin_mut.rs | 108 ++++++++
 rust/kernel/time/hrtimer/tbox.rs    | 120 +++++++++
 9 files changed, 1049 insertions(+), 2 deletions(-)
 create mode 100644 rust/kernel/time/hrtimer.rs
 create mode 100644 rust/kernel/time/hrtimer/arc.rs
 create mode 100644 rust/kernel/time/hrtimer/pin.rs
 create mode 100644 rust/kernel/time/hrtimer/pin_mut.rs
 create mode 100644 rust/kernel/time/hrtimer/tbox.rs
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