linux-kernel - [PATCH v2 09/13] rust: miscdevice: replace `MaybeUninit::zeroed().assume_init` with `pin

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Message-ID: <20250523145125.523275-10-lossin@kernel.org>
Date: Fri, 23 May 2025 16:51:05 +0200
From: Benno Lossin <lossin@...nel.org>
To: 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>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Lee Jones <lee@...nel.org>,
	Tamir Duberstein <tamird@...il.com>
Cc: Lyude Paul <lyude@...hat.com>,
	rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 09/13] rust: miscdevice: replace `MaybeUninit::zeroed().assume_init` with `pin_init::zeroed`

All types in `bindings` implement `Zeroable` if they can, so use
`pin_init::zeroed` instead of relying on `unsafe` code.

If this ends up not compiling in the future, something in bindgen or on
the C side changed and is most likely incorrect.

Signed-off-by: Benno Lossin <lossin@...nel.org>
---
 rust/kernel/miscdevice.rs | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index b4c5f74de23d..d66e6d3bb4ee 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -19,7 +19,7 @@
     str::CStr,
     types::{ForeignOwnable, Opaque},
 };
-use core::{marker::PhantomData, mem::MaybeUninit, pin::Pin};
+use core::{marker::PhantomData, pin::Pin};
 
 /// Options for creating a misc device.
 #[derive(Copy, Clone)]
@@ -31,8 +31,7 @@ pub struct MiscDeviceOptions {
 impl MiscDeviceOptions {
     /// Create a raw `struct miscdev` ready for registration.
     pub const fn into_raw<T: MiscDevice>(self) -> bindings::miscdevice {
-        // SAFETY: All zeros is valid for this C type.
-        let mut result: bindings::miscdevice = unsafe { MaybeUninit::zeroed().assume_init() };
+        let mut result: bindings::miscdevice = pin_init::zeroed();
         result.minor = bindings::MISC_DYNAMIC_MINOR as _;
         result.name = self.name.as_char_ptr();
         result.fops = MiscdeviceVTable::<T>::build();
@@ -309,8 +308,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
         } else {
             None
         },
-        // SAFETY: All zeros is a valid value for `bindings::file_operations`.
-        ..unsafe { MaybeUninit::zeroed().assume_init() }
+        ..pin_init::zeroed()
     };
 
     const fn build() -> &'static bindings::file_operations {
-- 
2.49.0