From patchwork Tue Oct 22 21:31:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Danilo Krummrich X-Patchwork-Id: 13846174 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 9E4CC1CC144; Tue, 22 Oct 2024 21:33:05 +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=1729632785; cv=none; b=RcX7CQ1T9cU/GE3H3Y47U65QPoWWdaONn12muBQkGerZjGo+Dez9U9xkPPyLgFj9As0U2LCdf8YOyX8AZS0vs4DY0Cm0lC7fWoBK5qgccyXzqM/C5Teuov1zoPy7uoV964NrULkfOMX3V/sWipZrEiaYQd9fVkZT6P28xkpVb7g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729632785; c=relaxed/simple; bh=Noe35AjzbyfXRcjkYKVDR0W06ecTf78zYPGz7+D0E1s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Pwyt88Ps80x5XlQFfO5IyJ/kA/wGyDnINX8xInHYQ0ATm2hWhLjXhWomZeCAyC0Nm/jLJnQ2smW3qPbnY+Yth3uncbmVKjTUfR0LkuvMXLffsM8/u0+zcqoxmtD/izAMb4R/w/kcgExw2I+tTdHhAPME+gXaeq48HYlK46njJ4A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mqr1DSmU; 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="mqr1DSmU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E28B0C4CEC3; Tue, 22 Oct 2024 21:32:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729632785; bh=Noe35AjzbyfXRcjkYKVDR0W06ecTf78zYPGz7+D0E1s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mqr1DSmUdTNhts/5YZyeQ9TYBo7V4UHbDjOAzKDQbubGiTEesY0Q5qsnyMQt/aq17 Ne0CR/z/I66/PClKt7DFvDr8bb2xsMI0zyktDzPtolMYo3yGsL4WjGnbhbyIYqMUR8 rOkvM4E+7AHHDZx0JSUSg6ppAn2gu74mJG8XU5ncWGME9ij0PrgCmjCYn+tlaanCnV IRnnvFSw/YIjLvHWepkQHUqoIes9wlQPiFGcsKETDqFjuabLWlY/LFI1G5mZqU0uzR YDNpoT4k1U/FYxPY3n9jkPqgPy52QHwK6IlgroUueefdP/v7he0mzBK+3XWo8rKyYE QSC2KRxF7UWHA== From: Danilo Krummrich To: gregkh@linuxfoundation.org, rafael@kernel.org, bhelgaas@google.com, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, tmgross@umich.edu, a.hindborg@samsung.com, aliceryhl@google.com, airlied@gmail.com, fujita.tomonori@gmail.com, lina@asahilina.net, pstanner@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, robh@kernel.org, daniel.almeida@collabora.com, saravanak@google.com Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, Wedson Almeida Filho , Danilo Krummrich Subject: [PATCH v3 06/16] rust: add rcu abstraction Date: Tue, 22 Oct 2024 23:31:43 +0200 Message-ID: <20241022213221.2383-7-dakr@kernel.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241022213221.2383-1-dakr@kernel.org> References: <20241022213221.2383-1-dakr@kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Wedson Almeida Filho Add a simple abstraction to guard critical code sections with an rcu read lock. Signed-off-by: Wedson Almeida Filho Signed-off-by: Danilo Krummrich --- rust/helpers/helpers.c | 1 + rust/helpers/rcu.c | 13 +++++++++++ rust/kernel/sync.rs | 1 + rust/kernel/sync/rcu.rs | 52 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 67 insertions(+) create mode 100644 rust/helpers/rcu.c create mode 100644 rust/kernel/sync/rcu.rs diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 20a0c69d5cc7..0720debccdd4 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -16,6 +16,7 @@ #include "mutex.c" #include "page.c" #include "rbtree.c" +#include "rcu.c" #include "refcount.c" #include "signal.c" #include "slab.c" diff --git a/rust/helpers/rcu.c b/rust/helpers/rcu.c new file mode 100644 index 000000000000..f1cec6583513 --- /dev/null +++ b/rust/helpers/rcu.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +void rust_helper_rcu_read_lock(void) +{ + rcu_read_lock(); +} + +void rust_helper_rcu_read_unlock(void) +{ + rcu_read_unlock(); +} diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 0ab20975a3b5..1806767359fe 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -11,6 +11,7 @@ mod condvar; pub mod lock; mod locked_by; +pub mod rcu; pub use arc::{Arc, ArcBorrow, UniqueArc}; pub use condvar::{new_condvar, CondVar, CondVarTimeoutResult}; diff --git a/rust/kernel/sync/rcu.rs b/rust/kernel/sync/rcu.rs new file mode 100644 index 000000000000..5a35495f69a4 --- /dev/null +++ b/rust/kernel/sync/rcu.rs @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! RCU support. +//! +//! C header: [`include/linux/rcupdate.h`](srctree/include/linux/rcupdate.h) + +use crate::bindings; +use core::marker::PhantomData; + +/// Evidence that the RCU read side lock is held on the current thread/CPU. +/// +/// The type is explicitly not `Send` because this property is per-thread/CPU. +/// +/// # Invariants +/// +/// The RCU read side lock is actually held while instances of this guard exist. +pub struct Guard { + _not_send: PhantomData<*mut ()>, +} + +impl Guard { + /// Acquires the RCU read side lock and returns a guard. + pub fn new() -> Self { + // SAFETY: An FFI call with no additional requirements. + unsafe { bindings::rcu_read_lock() }; + // INVARIANT: The RCU read side lock was just acquired above. + Self { + _not_send: PhantomData, + } + } + + /// Explicitly releases the RCU read side lock. + pub fn unlock(self) {} +} + +impl Default for Guard { + fn default() -> Self { + Self::new() + } +} + +impl Drop for Guard { + fn drop(&mut self) { + // SAFETY: By the type invariants, the rcu read side is locked, so it is ok to unlock it. + unsafe { bindings::rcu_read_unlock() }; + } +} + +/// Acquires the RCU read side lock. +pub fn read_lock() -> Guard { + Guard::new() +}