From mboxrd@z Thu Jan 1 00:00:00 1970 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 1EA781AE875; Tue, 20 May 2025 23:17:23 +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=1747783044; cv=none; b=BbGnWwmm+p4ACgM65mzjSUDtizIOEBsTCD/4n0bfRXMHDL8ArdULZvD3AHfvd+odsS3sZ4tXSBcm7JSG1qenWY0Fl+/gXxJlWO44CNFZPNESbzfR7z0PGSYo0BbXJ7KvHk9HUuwksA0ZSRkhT7UYkxPmiEsjlm6+1FKtP4h3Mck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747783044; c=relaxed/simple; bh=OLpprT4B3y/fOlPuThMEFMFgQ6AyOwL8XDRCThzZ/Hg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=nIy/XdkU8kDwG2CMeLS4b3NX8iyGU8SvtLzDIYkBPtXHCdOyxVMF/ped17k9j8WSPDKRTSnkoqp44qetWX8ewK23GM6Wf4jko0pCe/arFP5XEwfs95kQXEd+mewlfD8lGjU286x1Q8otEJsY4tGav8/Xr8KrqNwLYNQA3m8T2v0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RBIgW6i1; 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="RBIgW6i1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48449C4CEE9; Tue, 20 May 2025 23:17:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747783043; bh=OLpprT4B3y/fOlPuThMEFMFgQ6AyOwL8XDRCThzZ/Hg=; h=From:To:Cc:Subject:Date:From; b=RBIgW6i1K3c1FdJtmZllKzNnVbuHxGvJDyo+eBY+jRulc7Xqcx9GFeKBfI39Drqcc 3/o+RJE0uqyj+ZbdWY1yRGAbH6I60p9BO6UmiiBwi2Vfw/tnggbYDuUQuZEyFb2cZO Vvo61GDHFpedAuDXaXxWP8eW1jMgMLJEZThyNC4DjNLy9YdVD18OPiqNH34cVSx29c j5vRBR26eg2LeYrZls1sMGl7YhArhu3cfr3QhKoYFBdErvFdgW3WiuF/OK8aY1/qBp SyT0BoEz+vrd5mV9Vf3TxXYJ2F7uOwDGPhMctQEgT/aGmrxVot0vnHuzz/JPdJ4W7f KMigoXPqyNTtg== From: Benno Lossin To: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Lyude Paul , Mitchell Levy , Wedson Almeida Filho Cc: Benno Lossin , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] rust: sync: fix safety comment for `static_lock_class` Date: Wed, 21 May 2025 01:17:13 +0200 Message-ID: <20250520231714.323931-1-lossin@kernel.org> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The safety comment mentions lockdep -- which from a Rust perspective isn't important -- and doesn't mention the real reason for why it's sound to create `LockClassKey` as uninitialized memory. Signed-off-by: Benno Lossin --- I don't think we need to backport this. --- rust/kernel/sync.rs | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 36a719015583..a10c812d8777 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -93,8 +93,11 @@ fn drop(self: Pin<&mut Self>) { macro_rules! static_lock_class { () => {{ static CLASS: $crate::sync::LockClassKey = - // SAFETY: lockdep expects uninitialized memory when it's handed a statically allocated - // lock_class_key + // Lockdep expects uninitialized memory when it's handed a statically allocated `struct + // lock_class_key`. + // + // SAFETY: `LockClassKey` transparently wraps `Opaque` which permits uninitialized + // memory. unsafe { ::core::mem::MaybeUninit::uninit().assume_init() }; $crate::prelude::Pin::static_ref(&CLASS) }}; base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21 -- 2.49.0