Re: [PATCH v14 3/3] rust: replace `CStr` with `core::ffi::CStr`

["Benno Lossin" <lossin@kernel.org>]

On Thu Jul 10, 2025 at 4:53 PM CEST, Tamir Duberstein wrote:
> `kernel::ffi::CStr` was introduced in commit d126d2380131 ("rust: str:
> add `CStr` type") in November 2022 as an upstreaming of earlier work
> that was done in May 2021[0]. That earlier work, having predated the
> inclusion of `CStr` in `core`, largely duplicated the implementation of
> `std::ffi::CStr`.
>
> `std::ffi::CStr` was moved to `core::ffi::CStr` in Rust 1.64 in
> September 2022. Hence replace `kernel::str::CStr` with `core::ffi::CStr`
> to reduce our custom code footprint, and retain needed custom
> functionality through an extension trait.
>
> Add `CStr` to `ffi` and the kernel prelude.
>
> Link: https://github.com/Rust-for-Linux/linux/commit/faa3cbcca03d0dec8f8e43f1d8d5c0860d98a23f [0]
> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Tamir Duberstein <tamird@gmail.com>

Reviewed-by: Benno Lossin <lossin@kernel.org>

> ---
>  rust/ffi.rs                     |   2 +
>  rust/kernel/device.rs           |   1 +
>  rust/kernel/error.rs            |   2 +
>  rust/kernel/firmware.rs         |   9 +-
>  rust/kernel/prelude.rs          |   4 +-
>  rust/kernel/seq_file.rs         |   2 +-
>  rust/kernel/str.rs              | 395 +++++++++-------------------------------
>  rust/kernel/sync/condvar.rs     |   2 +-
>  rust/kernel/sync/lock.rs        |   2 +-
>  rust/kernel/sync/lock/global.rs |   2 +-
>  10 files changed, 106 insertions(+), 315 deletions(-)

> +/// Extensions to [`CStr`].
> +pub trait CStrExt {

Should we make this trait sealed?

---
Cheers,
Benno

>      /// Wraps a raw C string pointer.
>      ///
>      /// # Safety