From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	John Hubbard <jhubbard@nvidia.com>,
	Miguel Ojeda <ojeda@kernel.org>
Subject: [PATCH 6.18 0970/1250] rust: allow `clippy::as_underscore` in the generated bindings
Date: Thu, 17 Sep 2026 16:12:45 +0100
Message-ID: <20260917151618.306467515@linuxfoundation.org>
In-Reply-To: <20260917151551.901433442@linuxfoundation.org>
References: <20260917151551.901433442@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: John Hubbard <jhubbard@nvidia.com>

commit 2ac74c6db40adaa29c50cbb281ae9a6f63de18e1 upstream.

A CLIPPY=1 build emitted about 15000 `as _` conversion warnings, all of
them in bindgen's generated output and none in hand-written code.

[ The lint messages look like:

    error: using `as _` conversion
         --> rust/bindings/bindings_generated.rs:18947:9
          |
    18947 |         self._bitfield_1.get_const::<0usize, 16u8>() as u32 as _
          |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
          |                                                                |
          |                                                                help: consider giving the type explicitly: `u32`
          |
          = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.98.0/index.html#as_underscore
          = note: `-D clippy::as-underscore` implied by `-D warnings`
          = help: to override `-D warnings` add `#[allow(clippy::as_underscore)]`

    - Miguel ]

bindgen 0.73 returns each bitfield read through a trailing `as _`, and
0.72 returns it through a transmute, which the lint ignores. The
bindings and uapi crates allow `clippy::all` over the generated code.
That group does not cover `clippy::as_underscore`, a restriction lint.

Allow `clippy::as_underscore` by name in the bindings and uapi crates.

Assisted-by: LLM
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Link: https://patch.msgid.link/20260906215822.1201022-1-jhubbard@nvidia.com
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
[ Removed CI sentence. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 rust/bindings/lib.rs |    1 +
 rust/uapi/lib.rs     |    1 +
 2 files changed, 2 insertions(+)

--- a/rust/bindings/lib.rs
+++ b/rust/bindings/lib.rs
@@ -25,6 +25,7 @@
 )]
 
 #[allow(dead_code)]
+#[allow(clippy::as_underscore)]
 #[allow(clippy::cast_lossless)]
 #[allow(clippy::ptr_as_ptr)]
 #[allow(clippy::ref_as_ptr)]
--- a/rust/uapi/lib.rs
+++ b/rust/uapi/lib.rs
@@ -14,6 +14,7 @@
 #![cfg_attr(test, allow(unsafe_op_in_unsafe_fn))]
 #![allow(
     clippy::all,
+    clippy::as_underscore,
     clippy::cast_lossless,
     clippy::ptr_as_ptr,
     clippy::ref_as_ptr,