From nobody Sat Feb 7 23:24:16 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5462C30E830; Fri, 6 Feb 2026 21:11:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770412311; cv=none; b=k6C31KaBK+YDTbWJzixwdf1nIX2el7vJYkvGa0ghkV2tKr2wbUMBOjCTtldMc1fdGMCM4LaqVzPbPqjoW/BlIOgcBHqtDzMZYED9UI+FyrU923/449OEk5PnzgdIBPYD8pdWWJXA0WqZiP5X0CYnnhlePxdq/lWekyiwg6YXjBo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770412311; c=relaxed/simple; bh=2aA6TsP5TqOXxamqOrEM+ulf/tg/RPrxh0tZsqKQ8Qk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Mih86/LOBONYRoE5RZ3zbcul7fUDBLmqJgXrh58wPzsnsJ7DzxM06Qkt4DmdXdo0XddQtkfrAQ2WS4ZVTwPO1rF1vyRKWBZ84c8ekum3RAIJysLGJTueHYh45rP9SEXB2S2EXBu7f+RJKHEcQ3Jjbp3V5k8PP85wtokzD0BJxeY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rhBEKlTs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rhBEKlTs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7702FC116C6; Fri, 6 Feb 2026 21:11:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770412311; bh=2aA6TsP5TqOXxamqOrEM+ulf/tg/RPrxh0tZsqKQ8Qk=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=rhBEKlTsP62RAZDNXL4f6dTWS2K126rDj/IyPLRJ9fZW85Dhc0DG7jYthxD5w0iMs azv0CWMNz2OaTIjSVyKOPoZn6wHpdz8xmO5Tfm0uGZD+9Jkddc2azvX+jFgX0fJ1ap DMaQ5S2sebc4qRDD7FAfwPSIzixaAwphXH27Otk7KqchRQ5LGWaB92agMNmjW2EnRS xJXG7gzfAJdjKjVBiGs8Y9o2LgbJJyuEUN9BrA5aQY9U86ITgX7eTMKW4AfIqFLPEj +EK6tFG44dEQhQPqjuADRRkbk3zMWlPylpJsQrOGn0M9dSzxBA8BrRl0KKh/3o8ypb 1GBrfia7yZKPA== From: Andreas Hindborg Date: Fri, 06 Feb 2026 22:10:50 +0100 Subject: [PATCH v2 04/11] rust: xarray: add `XArrayState` Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260206-xarray-entry-send-v2-4-91c41673fd30@kernel.org> References: <20260206-xarray-entry-send-v2-0-91c41673fd30@kernel.org> In-Reply-To: <20260206-xarray-entry-send-v2-0-91c41673fd30@kernel.org> To: Tamir Duberstein , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Alice Ryhl , Trevor Gross , Danilo Krummrich , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo Cc: Daniel Gomez , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andreas Hindborg X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=3142; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=2aA6TsP5TqOXxamqOrEM+ulf/tg/RPrxh0tZsqKQ8Qk=; b=owEBbQKS/ZANAwAKAeG4Gj55KGN3AcsmYgBphljkR6yFU74Qctxwfi+Hjmm+uCS+oAhwJVObd 03DdYekpUGJAjMEAAEKAB0WIQQSwflHVr98KhXWwBLhuBo+eShjdwUCaYZY5AAKCRDhuBo+eShj d7NJEACUN4BBgh5y31PGzMdcKchA+Aw6rT5w2nYg1DwlVMsSRzL7BZOOsYX0BrXCfJtsmRg91dM dLzCLv7Ar7zwcI80iJnrAG8sr+wg5wtepKUfDrTMbSyi6vJp4u+XfwqB4QS8iP36nQTIZ/ostYU 7xwkrXbTLtNr++3c+mo0tU1yUB9cFSYFHcfOR+KU4OI+OaV0agbPhkCur+W+yFgaE+yXzsJfuj+ /faayPfcGoTSrap9G3p78GaKxMKDiYTSVko8qtgbqoBvamPr7ZAokSztOfM/wLhu7lJD2CMAN5H f6FfU4KMs+gZXuHR3iyhDOVBXqpW60wdbvE4+etEFbY7FkY4SAUpXtLdgRb4YwW2M3lOOMUgFzz H5jeeUQhUFkib5dWWmahTU7iCe8BMDctvKP/BaK0M9y0g5FdyW2OVS75nG57V6rO/jsMUeM4b2Y ew/cD84r8n7LV1J5W/A5oiiPHXbSKQ+fHIJNSWxZ/zh+TrdED5Moo1ul2gBXJKJ2kguc1+Yx2+0 xVBGydN2BIb8KXmQbJr5gL1gSGnuuk0iJCKmDKYCW5baQhMbYwxTc4yXO4hNY548Xc+BepwqoH0 +Ujvysi8N7EqQPhESEe2AHlSXKCrLA/HEUHWrtdJlujsGqNVdWiTk+ZSXyZPETCnTzfxXLHjaT2 O0AcmXow/xyhDvA== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 Add `XArrayState` as internal state for XArray iteration and entry operations. This struct wraps the C `xa_state` structure and holds a reference to a `Guard` to ensure exclusive access to the XArray for the lifetime of the state object. The `XAS_RESTART` constant is also exposed through the bindings helper to properly initialize the `xa_node` field. The struct and its constructor are marked with `#[expect(dead_code)]` as there are no users yet. We will remove this annotation in a later patch. Signed-off-by: Andreas Hindborg --- rust/bindings/bindings_helper.h | 1 + rust/kernel/xarray.rs | 41 +++++++++++++++++++++++++++++++++++++= +++- 2 files changed, 41 insertions(+), 1 deletion(-) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index a067038b4b422..58605c32e8102 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -117,6 +117,7 @@ const xa_mark_t RUST_CONST_HELPER_XA_PRESENT =3D XA_PRE= SENT; =20 const gfp_t RUST_CONST_HELPER_XA_FLAGS_ALLOC =3D XA_FLAGS_ALLOC; const gfp_t RUST_CONST_HELPER_XA_FLAGS_ALLOC1 =3D XA_FLAGS_ALLOC1; +const size_t RUST_CONST_HELPER_XAS_RESTART =3D (size_t)XAS_RESTART; =20 const vm_flags_t RUST_CONST_HELPER_VM_MERGEABLE =3D VM_MERGEABLE; const vm_flags_t RUST_CONST_HELPER_VM_READ =3D VM_READ; diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs index ede48b5e1dba3..d1246ec114898 100644 --- a/rust/kernel/xarray.rs +++ b/rust/kernel/xarray.rs @@ -8,7 +8,10 @@ iter, marker::PhantomData, pin::Pin, - ptr::NonNull, // + ptr::{ + null_mut, + NonNull, // + }, }; use kernel::{ alloc, @@ -319,6 +322,42 @@ pub fn store( } } =20 +/// Internal state for XArray iteration and entry operations. +/// +/// # Invariants +/// +/// - `state` is always a valid `bindings::xa_state`. +#[expect(dead_code)] +pub(crate) struct XArrayState<'a, 'b, T: ForeignOwnable> { + /// Holds a reference to the lock guard to ensure the lock is not drop= ped + /// while `Self` is live. + _access: PhantomData<&'b Guard<'a, T>>, + state: bindings::xa_state, +} + +impl<'a, 'b, T: ForeignOwnable> XArrayState<'a, 'b, T> { + #[expect(dead_code)] + fn new(access: &'b Guard<'a, T>, index: usize) -> Self { + let ptr =3D access.xa.xa.get(); + // INVARIANT: We initialize `self.state` to a valid value below. + Self { + _access: PhantomData, + state: bindings::xa_state { + xa: ptr, + xa_index: index, + xa_shift: 0, + xa_sibs: 0, + xa_offset: 0, + xa_pad: 0, + xa_node: bindings::XAS_RESTART as *mut bindings::xa_node, + xa_alloc: null_mut(), + xa_update: None, + xa_lru: null_mut(), + }, + } + } +} + // SAFETY: `XArray` has no shared mutable state so it is `Send` iff `T`= is `Send`. unsafe impl Send for XArray {} =20 --=20 2.51.2