netdev - Re: [PATCH v13 3/5] rust: replace `CStr` with `core::ffi::CStr`

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Message-Id: <DB3AFTUC22W1.39C4DMWSENZGB@kernel.org>
Date: Fri, 04 Jul 2025 15:00:24 +0200
From: "Benno Lossin" <lossin@...nel.org>
To: "Tamir Duberstein" <tamird@...il.com>, "Michal Rostecki"
 <vadorovsky@...tonmail.com>, "Miguel Ojeda" <ojeda@...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>, "Andreas Hindborg" <a.hindborg@...nel.org>,
 "Alice Ryhl" <aliceryhl@...gle.com>, "Trevor Gross" <tmgross@...ch.edu>,
 "Brendan Higgins" <brendan.higgins@...ux.dev>, "David Gow"
 <davidgow@...gle.com>, "Rae Moar" <rmoar@...gle.com>, "Danilo Krummrich"
 <dakr@...nel.org>, "Maarten Lankhorst" <maarten.lankhorst@...ux.intel.com>,
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 <tzimmermann@...e.de>, "David Airlie" <airlied@...il.com>, "Simona Vetter"
 <simona@...ll.ch>, "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
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 <mcgrof@...nel.org>, "Russ Weight" <russ.weight@...ux.dev>, "FUJITA
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 <sboyd@...nel.org>
Cc: <rust-for-linux@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <linux-kselftest@...r.kernel.org>, <kunit-dev@...glegroups.com>,
 <dri-devel@...ts.freedesktop.org>, <netdev@...r.kernel.org>,
 <devicetree@...r.kernel.org>, <llvm@...ts.linux.dev>,
 <linux-pci@...r.kernel.org>, <nouveau@...ts.freedesktop.org>,
 <linux-block@...r.kernel.org>, <linux-pm@...r.kernel.org>,
 <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v13 3/5] rust: replace `CStr` with `core::ffi::CStr`

On Tue Jul 1, 2025 at 6:49 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.
>
> C-String literals were added in Rust 1.77, while our MSRV is 1.78. Thus
> opportunistically replace instances of `kernel::c_str!` with C-String
> literals where other code changes were already necessary or where
> existing code triggered clippy lints; the rest will be done in a later
> commit.
>
> Link: https://github.com/Rust-for-Linux/linux/commit/faa3cbcca03d0dec8f8e43f1d8d5c0860d98a23f [0]
> Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
> Signed-off-by: Tamir Duberstein <tamird@...il.com>
> ---
>  drivers/gpu/drm/drm_panic_qr.rs |   2 +-
>  rust/kernel/auxiliary.rs        |   4 +-
>  rust/kernel/configfs.rs         |   4 +-
>  rust/kernel/cpufreq.rs          |   2 +-
>  rust/kernel/device.rs           |   4 +-
>  rust/kernel/drm/device.rs       |   4 +-
>  rust/kernel/error.rs            |   4 +-
>  rust/kernel/firmware.rs         |  11 +-
>  rust/kernel/kunit.rs            |   6 +-
>  rust/kernel/miscdevice.rs       |   2 +-
>  rust/kernel/net/phy.rs          |   2 +-
>  rust/kernel/of.rs               |   2 +-
>  rust/kernel/prelude.rs          |   5 +-
>  rust/kernel/seq_file.rs         |   4 +-
>  rust/kernel/str.rs              | 394 +++++++++++-----------------------------
>  rust/kernel/sync/condvar.rs     |   2 +-
>  rust/kernel/sync/lock.rs        |   2 +-
>  rust/kernel/sync/lock/global.rs |   2 +-
>  samples/rust/rust_configfs.rs   |   2 +-
>  19 files changed, 140 insertions(+), 318 deletions(-)

Is it also possible to split this? First rename the existing functions
on our CStr to match upstream & then you don't need to do the rename &
removal of our CStr in the same patch?

---
Cheers,
Benno