linux-kernel - [PATCH v5 2/6] rust: bitmap: add BitmapVec::new

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Message-ID: <20251112-binder-bitmap-v5-2-8b9d7c7eca82@google.com>
Date: Wed, 12 Nov 2025 12:47:20 +0000
From: Alice Ryhl <aliceryhl@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Yury Norov <yury.norov@...il.com>
Cc: "Arve Hjønnevåg" <arve@...roid.com>, Todd Kjos <tkjos@...roid.com>, 
	Martijn Coenen <maco@...roid.com>, Joel Fernandes <joelagnelf@...dia.com>, 
	Christian Brauner <brauner@...nel.org>, Carlos Llamas <cmllamas@...gle.com>, 
	Suren Baghdasaryan <surenb@...gle.com>, Burak Emir <bqe@...gle.com>, Miguel Ojeda <ojeda@...nel.org>, 
	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>, Trevor Gross <tmgross@...ch.edu>, 
	Danilo Krummrich <dakr@...nel.org>, rust-for-linux@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Alice Ryhl <aliceryhl@...gle.com>
Subject: [PATCH v5 2/6] rust: bitmap: add BitmapVec::new_inline()

This constructor is useful when you just want to create a BitmapVec
without allocating but don't care how large it is.

Acked-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
Reviewed-by: Burak Emir <bqe@...gle.com>
Reviewed-by: Danilo Krummrich <dakr@...nel.org>
Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>
---
 rust/kernel/bitmap.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/rust/kernel/bitmap.rs b/rust/kernel/bitmap.rs
index 0705646c6251a49f213a45f1f013cb9eb2ed81de..bbbf0f9e5d9251953584581af57042143447b996 100644
--- a/rust/kernel/bitmap.rs
+++ b/rust/kernel/bitmap.rs
@@ -230,6 +230,16 @@ impl BitmapVec {
     /// The maximum length that uses the inline representation.
     pub const MAX_INLINE_LEN: usize = usize::BITS as usize;
 
+    /// Construct a longest possible inline [`BitmapVec`].
+    #[inline]
+    pub fn new_inline() -> Self {
+        // INVARIANT: `nbits <= NO_ALLOC_MAX_LEN`, so an inline bitmap is the right repr.
+        BitmapVec {
+            repr: BitmapRepr { bitmap: 0 },
+            nbits: BitmapVec::NO_ALLOC_MAX_LEN,
+        }
+    }
+
     /// Constructs a new [`BitmapVec`].
     ///
     /// Fails with [`AllocError`] when the [`BitmapVec`] could not be allocated. This

-- 
2.51.2.1041.gc1ab5b90ca-goog