Re: [PATCH v3 01/13] rust: sync: introduce `LockClassKey`

Martin Rodriguez Reboredo
2023-04-09T16:47:04Z

On 4/8/23 04:53, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@microsoft.com>
>
> It is a wrapper around C's `lock_class_key`, which is used by the
> synchronisation primitives that are checked with lockdep. This is in
> preparation for introducing Rust abstractions for these primitives.
>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Waiman Long <longman@redhat.com>
> Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
> ---
> v1 -> v2: Fixed a typo in comment
> v2 -> v3: Replaced `core` with `::core` in macro
>
> rust/kernel/sync.rs | 45 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
>
> diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs
> index 33da23e3076d..541d235ffbeb 100644
> --- a/rust/kernel/sync.rs
> +++ b/rust/kernel/sync.rs
> @@ -5,6 +5,51 @@
> //! This module contains the kernel APIs related to synchronisation that have been ported or
> //! wrapped for usage by Rust code in the kernel.
>
> +use crate::types::Opaque;
> +
> mod arc;
>
> pub use arc::{Arc, ArcBorrow, UniqueArc};
> +
> +/// Represents a lockdep class. It's a wrapper around C's `lock_class_key`.
> +#[repr(transparent)]
> +pub struct LockClassKey(Opaque<bindings::lock_class_key>);
> +
> +// SAFETY: `bindings::lock_class_key` is designed to be used concurrently from multiple threads and
> +// provides its own synchronization.
> +unsafe impl Sync for LockClassKey {}
> +
> +impl LockClassKey {
> + /// Creates a new lock class key.
> + pub const fn new() -> Self {
> + Self(Opaque::uninit())
> + }
> +
> + #[allow(dead_code)]
> + pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key {
> + self.0.get()
> + }
> +}
> +
> +/// Defines a new static lock class and returns a pointer to it.
> +#[doc(hidden)]
> +#[macro_export]
> +macro_rules! static_lock_class {
> + () => {{
> + static CLASS: $crate::sync::LockClassKey = $crate::sync::LockClassKey::new();
> + &CLASS
> + }};
> +}
> +
> +/// Returns the given string, if one is provided, otherwise generates one based on the source code
> +/// location.
> +#[doc(hidden)]
> +#[macro_export]
> +macro_rules! optional_name {
> + () => {
> + $crate::c_str!(::core::concat!(::core::file!(), ":", ::core::line!()))
> + };
> + ($name:literal) => {
> + $crate::c_str!($name)
> + };
> +}

Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>