Re: [PATCH v4 2/2] rust: lockdep: Use Pin for all LockClassKey usages

[Benno Lossin <benno.lossin@proton.me>]

On 08.02.25 01:39, Mitchell Levy wrote:
> Reintroduce dynamically-allocated LockClassKeys such that they are
> automatically (de)registered. Require that all usages of LockClassKeys
> ensure that they are Pin'd.
> 
> Currently, only `'static` LockClassKeys are supported, so Pin is
> redundant. However, it is intended that dynamically-allocated
> LockClassKeys will eventually be supported, so using Pin from the outset
> will make that change simpler.
> 
> Closes: https://github.com/Rust-for-Linux/linux/issues/1102
> Suggested-by: Benno Lossin <benno.lossin@proton.me>
> Suggested-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Mitchell Levy <levymitchell0@gmail.com>

One nit below, but it's fine.

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

> ---
>  rust/helpers/helpers.c          |  1 +
>  rust/helpers/sync.c             | 13 ++++++++++
>  rust/kernel/sync.rs             | 57 ++++++++++++++++++++++++++++++++++++++---
>  rust/kernel/sync/condvar.rs     |  5 ++--
>  rust/kernel/sync/lock.rs        |  9 +++----
>  rust/kernel/sync/lock/global.rs |  5 ++--
>  rust/kernel/sync/poll.rs        |  2 +-
>  rust/kernel/workqueue.rs        |  2 +-
>  8 files changed, 78 insertions(+), 16 deletions(-)

[...]

> diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
> index eb80048e0110..6dafe338bbc7 100644
> --- a/rust/kernel/sync/lock.rs
> +++ b/rust/kernel/sync/lock.rs
> @@ -7,12 +7,9 @@
> 
>  use super::LockClassKey;
>  use crate::{
> -    init::PinInit,
> -    pin_init,
> -    str::CStr,
> -    types::{NotThreadSafe, Opaque, ScopeGuard},
> +    init::PinInit, pin_init, str::CStr, types::NotThreadSafe, types::Opaque, types::ScopeGuard,

Why does this change exist? I prefer imports to be merged.

---
Cheers,
Benno

>  };
> -use core::{cell::UnsafeCell, marker::PhantomPinned};
> +use core::{cell::UnsafeCell, marker::PhantomPinned, pin::Pin};
>  use macros::pin_data;
> 
>  pub mod mutex;
> @@ -129,7 +126,7 @@ unsafe impl<T: ?Sized + Send, B: Backend> Sync for Lock<T, B> {}
> 
>  impl<T, B: Backend> Lock<T, B> {
>      /// Constructs a new lock initialiser.
> -    pub fn new(t: T, name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> {
> +    pub fn new(t: T, name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self> {
>          pin_init!(Self {
>              data: UnsafeCell::new(t),
>              _pin: PhantomPinned,