From: Danilo Krummrich <dakr@kernel.org>
To: gregkh@linuxfoundation.org, rafael@kernel.org,
	acourbot@nvidia.com, aliceryhl@google.com,
	david.m.ertman@intel.com, ira.weiny@intel.com, leon@kernel.org,
	ojeda@kernel.org, boqun@kernel.org, gary@garyguo.net,
	bjorn3_gh@protonmail.com, lossin@kernel.org,
	a.hindborg@kernel.org, tmgross@umich.edu
Cc: driver-core@lists.linux.dev, linux-kernel@vger.kernel.org,
	nova-gpu@lists.linux.dev, dri-devel@lists.freedesktop.org,
	rust-for-linux@vger.kernel.org,
	Danilo Krummrich <dakr@kernel.org>
Subject: [PATCH v2 1/3] rust: alloc: add Box::zeroed()
Date: Tue,  5 May 2026 17:23:07 +0200	[thread overview]
Message-ID: <20260505152400.3905096-2-dakr@kernel.org> (raw)
In-Reply-To: <20260505152400.3905096-1-dakr@kernel.org>

Add Box::zeroed() for T: Zeroable types.

This allocates with __GFP_ZERO directly, letting the underlying
allocator deal with zeroing out the memory compared to
Box::new(T::zeroed(), flags).

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/alloc/kbox.rs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index bd6da02c7ab8..c824ed6e1523 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -19,6 +19,7 @@
 use crate::fmt;
 use crate::init::InPlaceInit;
 use crate::page::AsPageIter;
+use crate::prelude::*;
 use crate::types::ForeignOwnable;
 use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption};
 
@@ -256,6 +257,27 @@ pub fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>, A>, AllocError> {
         Ok(Box(ptr.cast(), PhantomData))
     }
 
+    /// Creates a new zero-initialized `Box<T, A>`.
+    ///
+    /// New memory is allocated with `A` and the [`__GFP_ZERO`] flag. The allocation may fail, in
+    /// which case an error is returned. For ZSTs no memory is allocated.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let b = KBox::<[u8; 128]>::zeroed(GFP_KERNEL)?;
+    /// assert_eq!(*b, [0; 128]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn zeroed(flags: Flags) -> Result<Self, AllocError>
+    where
+        T: Zeroable,
+    {
+        // SAFETY: `__GFP_ZERO` guarantees the memory is zeroed; `T: Zeroable` guarantees that
+        // all-zeroes is a valid bit pattern for `T`.
+        Ok(unsafe { Self::new_uninit(flags | __GFP_ZERO)?.assume_init() })
+    }
+
     /// Constructs a new `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then `x` will be
     /// pinned in memory and can't be moved.
     #[inline]
-- 
2.54.0

next prev parent reply	other threads:[~2026-05-05 15:24 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-05 15:23 [PATCH v2 0/3] rust: auxiliary: replace drvdata() with registration data Danilo Krummrich
2026-05-05 15:23 ` Danilo Krummrich [this message]
2026-05-05 15:48   ` [PATCH v2 1/3] rust: alloc: add Box::zeroed() Alice Ryhl
2026-05-05 20:04     ` Danilo Krummrich
2026-05-05 20:06       ` Gary Guo
2026-05-05 20:10         ` Danilo Krummrich
2026-05-05 15:23 ` [PATCH v2 2/3] rust: auxiliary: add registration data to auxiliary devices Danilo Krummrich
2026-05-06 12:42   ` Alice Ryhl
2026-05-06 13:41     ` Gary Guo
2026-05-10 21:39       ` Danilo Krummrich
2026-05-11 14:53         ` Danilo Krummrich
2026-05-05 15:23 ` [PATCH v2 3/3] rust: driver core: remove drvdata() and driver_type Danilo Krummrich
2026-05-11 15:36 ` [PATCH v2 0/3] rust: auxiliary: replace drvdata() with registration data Danilo Krummrich

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