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 3573660860; Mon, 26 Feb 2024 13:55:47 +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=1708955748; cv=none; b=F2UWW2el+PoCqZBrefTEJnzFs5nhuUuRNfQoPlGnyphIl/7/oIGIy2gRsVyAg7O1SrOPrFDWXXAX6ZaZerR0opJxuQZ0VjnfBTZFQ2x3Hm4S98VjbWiqzwQUdJD88CICzFGC29AMSZ0R474TtFVXIM5tv9px48Y2uriFwPOxaTk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708955748; c=relaxed/simple; bh=Emy8hODkmYz5l9/3gRLjcbkZM9jZtfeB+DF9ipyZg0U=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=Zrqs2cQcofsSgbMIcZ3jkyDfWe8nh9VnukPBoQOszSfz67lNDkJQkyD06UIoCy9Y9g6ZffB+e7ATbL0ppuJ7DvewXrMKAj5qOkU72QsL2hdzh/iqfLuYGkykzWb8T0uy+WwJHeiL+jVXwohFhtJaZiw49pQyFtRYr37SyZfPEEQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EJTIxIyZ; 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="EJTIxIyZ" Received: by smtp.kernel.org (Postfix) with ESMTPS id 98DD1C43390; Mon, 26 Feb 2024 13:55:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708955747; bh=Emy8hODkmYz5l9/3gRLjcbkZM9jZtfeB+DF9ipyZg0U=; h=From:Date:Subject:To:Cc:Reply-To:From; b=EJTIxIyZ5a38kRyt1gcNNyfrWkbhG9pSzFRamisGy1ygB/RnL3HU+EtHz47vjSaCA Uk9XGK8NxJm1KBIG4h8xhOw2WNjmSKLn6QuA917oB3BdESHoXDkrKQukoB77ikAyoi 83xyj5dQ97WHMoRC+AfxAHkype9cxth2h+l5Ig7aRz5bPOX5CIFIaUBtb38iUi5ANF 0GwPAwb5PE790ga34ex4UWweYG/IsIhdaQF6bRTUxKc7Ot7YmsPpyZLH9FUr4dXeQ2 2X+Y+9WOX5MgUkHydx4ISWEM54s+FpdWiu17QULzZnQXyUqhPkgoJF0YPLF7JlMPjs UJSlfsc9UQFLA== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84E58C48BF6; Mon, 26 Feb 2024 13:55:47 +0000 (UTC) From: Mathys-Gasnier via B4 Relay Date: Mon, 26 Feb 2024 14:55:47 +0100 Subject: [PATCH v4] rust: locks: Add `get_mut` method to `Lock` Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20240226-rust-locks-get-mut-v4-1-24abf57707a8@gmail.com> X-B4-Tracking: v=1; b=H4sIAGKY3GUC/23NQQ6CMBCF4auQrq3pTIugK+9hXMB0wEahpkWiM dzdohtiWP4vmW/eInJwHMUhe4vAo4vO9ynMJhN0qfqWpbOpBSo0CqCU4REHefN0jbLlQXaPQZJ BVSAosEUl0uE9cOOeX/R0Tn1xcfDh9f0xwrz+OFT7NW4ECZJY59CQtmyKY9tV7rYl34mZG3FBA K4SmIicyGpDWBeq/if0gsB1QifC6rLaNaa2rO2SmKbpAwZCFhE6AQAA To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Martin Rodriguez Reboredo , Mathys-Gasnier X-Mailer: b4 0.12.4 X-Developer-Signature: v=1; a=ed25519-sha256; t=1708955747; l=2602; i=mathys35.gasnier@gmail.com; s=20240118; h=from:subject:message-id; bh=kDDO5igmp8sHMJQ33zb3ZYMBa3AMIqzPPer9XYO98Lo=; b=2Mlo8HK/4uPZRMpwJZRxkIbJoJnJnrJpKYcLID/FnTnK1ceAVASzr1Qaij59qMg9WNpDWUIMZ 9Fn4o5lHlDdBgYl12WxZDNVSpumToeoyu3ohBzrCXGbe09RGmXfIUiI X-Developer-Key: i=mathys35.gasnier@gmail.com; a=ed25519; pk=C5tqKAA3Ua7li5s3a+q2aDelT2j98/yjGg2nEVGArXE= X-Endpoint-Received: by B4 Relay for mathys35.gasnier@gmail.com/20240118 with auth_id=129 X-Original-From: Mathys-Gasnier Reply-To: From: Mathys-Gasnier Having a mutable reference guarantees that no other threads have access to the lock, so we can take advantage of that to grant callers access to the protected data without the the cost of acquiring and releasing the locks. Since the lifetime of the data is tied to the mutable reference, the borrow checker guarantees that the usage is safe. Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Mathys-Gasnier --- Changes in v4: - Improved documentation - Link to v3: https://lore.kernel.org/r/20240222-rust-locks-get-mut-v3-1-d38a6f4bde3d@gmail.com Changes in v3: - Changing the function to take a `Pin<&mut self>` instead of a `&mut self` - Removed reviewed-by's since big changes were made. Please take another look. - Link to v2: https://lore.kernel.org/r/20240212-rust-locks-get-mut-v2-1-5ccd34c2b70b@gmail.com Changes in v2: - Improved doc comment. - Link to v1: https://lore.kernel.org/r/20240209-rust-locks-get-mut-v1-1-ce351fc3de47@gmail.com --- rust/kernel/sync/lock.rs | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index f12a684bc957..a563991bf851 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -7,7 +7,11 @@ use super::LockClassKey; use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque, types::ScopeGuard}; -use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; +use core::{ + cell::UnsafeCell, + marker::{PhantomData, PhantomPinned}, + pin::Pin, +}; use macros::pin_data; pub mod mutex; @@ -121,6 +125,17 @@ pub fn lock(&self) -> Guard<'_, T, B> { // SAFETY: The lock was just acquired. unsafe { Guard::new(self, state) } } + + /// Gets the data contained in the lock. + /// + /// Having a mutable reference to the lock guarantees that no other threads have access to the lock. + /// And because `data` is not structurally pinned, + /// it is safe to get a mutable reference to the lock content. + pub fn get_mut(self: Pin<&mut Self>) -> &mut T { + // SAFETY: The lock will only be used to get a reference to the data, therefore self won't get moved + let lock = unsafe { self.get_unchecked_mut() }; + lock.data.get_mut() + } } /// A lock guard. --- base-commit: 711cbfc717650532624ca9f56fbaf191bed56e67 change-id: 20240118-rust-locks-get-mut-c42072101d7a Best regards, -- Mathys-Gasnier