linux-kernel - [PATCH v2] rust: device: allow `Device<DeviceContext>::parent()`

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250429210629.513521-1-ojeda@kernel.org>
Date: Tue, 29 Apr 2025 23:06:29 +0200
From: Miguel Ojeda <ojeda@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>
Cc: Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev
Subject: [PATCH v2] rust: device: allow `Device<DeviceContext>::parent()`

When `CONFIG_AUXILIARY_BUS` is disabled, `parent()` is still dead code:

    error: method `parent` is never used
      --> rust/kernel/device.rs:71:19
       |
    64 | impl<Ctx: DeviceContext> Device<Ctx> {
       | ------------------------------------ method in this implementation
    ...
    71 |     pub(crate) fn parent(&self) -> Option<&Self> {
       |                   ^^^^^^
       |
       = note: `-D dead-code` implied by `-D warnings`
       = help: to override `-D warnings` add `#[allow(dead_code)]`

Thus reintroduce the `expect`, but now as a conditional one. Do so as
`dead_code` since that is narrower.

An `allow` would also be possible, but Danilo wants to catch new users
in the future [1].

Link: https://lore.kernel.org/rust-for-linux/aBE8qQrpXOfru_K3@pollux/ [1]
Fixes: ce735e73dd59 ("rust: auxiliary: add auxiliary device / driver abstractions")
Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
---
 rust/kernel/device.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 40c1f549b0ba..f08583fa39c9 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -68,6 +68,7 @@ pub(crate) fn as_raw(&self) -> *mut bindings::device {
     }
 
     /// Returns a reference to the parent device, if any.
+    #[cfg_attr(not(CONFIG_AUXILIARY_BUS), expect(dead_code))]
     pub(crate) fn parent(&self) -> Option<&Self> {
         // SAFETY:
         // - By the type invariant `self.as_raw()` is always valid.

base-commit: ce735e73dd59b169b877cedd0753297c81c2a091
-- 
2.49.0