From patchwork Tue Dec 10 22:46:31 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Danilo Krummrich X-Patchwork-Id: 13902397 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 4F936211277; Tue, 10 Dec 2024 22:50:25 +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=1733871025; cv=none; b=bz/DUb+UAFq7Y1iMJcQuvv0PWSFaZaNbmVVbWLfiMk4daD57+6DsB0kHvpttQbFJs/O2fGiAbjxOVNovwi4IhT0VXbcj3fIUcndQ107atvGKL2sKtKEw5ADdpClamufkXY619WolP9nL48gpN3Iq+vtg0zWj3Wlu9PGicBaTFaI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733871025; c=relaxed/simple; bh=e8fdtrnJQD4e+C55I6bdwSGwqVTXC5F9OkgGcKeaTSw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QczoYa0AaxRI+TacMd1zHW0SqP4hjfFzqPfghjKeklfiW1fKVc2aJXAQkAAVlzeWkjV2fzcg4lSMiDJfQhPHh6k1eHTdsdFNxMWxq8o9jnDkkwguDj+vKSzQnDWvIcFAxchDDrl2ryvJS3Ja8SAJHO73DoWV2+5n5g+f0QAeO5A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rtkD9aXC; 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="rtkD9aXC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFCC6C4CEDF; Tue, 10 Dec 2024 22:50:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733871024; bh=e8fdtrnJQD4e+C55I6bdwSGwqVTXC5F9OkgGcKeaTSw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rtkD9aXCa5pE8XnawaWoQt5/oJxrAbmwanrlOpmLdP8aa7THMZwwCBioMNcpnkSUN soXFil2j3pPN+PCRbc1nvo8LcRSxn3Uwjk/GXgmYLPj5CSIE2G4rkcsF9Qdfa0/Zlb L8D1g89GQpzRCPJ0xjThS3Rbg0K6MC4LIyd4JtD/gllS3/Gg7ifKXVeRB+AZrrxGFT 4vuzVvHTglIr99ahVLdE6nTpn+4/s/ZVvVPC6Z7NN53y/85rAheYaTk2T/+AEdzmHA ufh7Uu4JoafJao7eCojqrtcULfe0PnWK5gpwZ7+MgjR+6FR2ptrWYG9NGUyR2FFvaG Yf888l4c2QxUQ== 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, dirk.behme@de.bosch.com, j@jannau.net, fabien.parent@linaro.org, chrisi.schrefl@gmail.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 v5 04/16] rust: add rcu abstraction Date: Tue, 10 Dec 2024 23:46:31 +0100 Message-ID: <20241210224947.23804-5-dakr@kernel.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241210224947.23804-1-dakr@kernel.org> References: <20241210224947.23804-1-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 Co-developed-by: Danilo Krummrich Signed-off-by: Danilo Krummrich Reviewed-by: Boqun Feng --- rust/helpers/helpers.c | 1 + rust/helpers/rcu.c | 13 ++++++++++++ rust/kernel/sync.rs | 1 + rust/kernel/sync/rcu.rs | 47 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 62 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 dcf827a61b52..060750af6524 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -20,6 +20,7 @@ #include "page.c" #include "pid_namespace.c" #include "rbtree.c" +#include "rcu.c" #include "refcount.c" #include "security.c" #include "signal.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 1eab7ebf25fd..0654008198b2 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -12,6 +12,7 @@ pub mod lock; mod locked_by; pub mod poll; +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..3beef70d5f34 --- /dev/null +++ b/rust/kernel/sync/rcu.rs @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! RCU support. +//! +//! C header: [`include/linux/rcupdate.h`](srctree/include/linux/rcupdate.h) + +use crate::{bindings, types::NotThreadSafe}; + +/// 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(NotThreadSafe); + +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(NotThreadSafe) + } + + /// 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() +}