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Message-ID: <20241101060237.1185533-13-boqun.feng@gmail.com>
Date: Thu, 31 Oct 2024 23:02:35 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: rust-for-linux@...r.kernel.org,
rcu@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-arch@...r.kernel.org,
llvm@...ts.linux.dev,
lkmm@...ts.linux.dev
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
Wedson Almeida Filho <wedsonaf@...il.com>,
Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...sung.com>,
Alice Ryhl <aliceryhl@...gle.com>,
Alan Stern <stern@...land.harvard.edu>,
Andrea Parri <parri.andrea@...il.com>, Will Deacon <will@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Nicholas Piggin <npiggin@...il.com>, David Howells <dhowells@...hat.com>,
Jade Alglave <j.alglave@....ac.uk>, Luc Maranget <luc.maranget@...ia.fr>,
"Paul E. McKenney" <paulmck@...nel.org>,
Akira Yokosawa <akiyks@...il.com>, Daniel Lustig <dlustig@...dia.com>,
Joel Fernandes <joel@...lfernandes.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>, kent.overstreet@...il.com,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>, elver@...gle.com,
Mark Rutland <mark.rutland@....com>,
Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Catalin Marinas <catalin.marinas@....com>, torvalds@...ux-foundation.org,
linux-arm-kernel@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
Trevor Gross <tmgross@...ch.edu>, dakr@...hat.com,
Frederic Weisbecker <frederic@...nel.org>,
Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
Josh Triplett <josh@...htriplett.org>,
Uladzislau Rezki <urezki@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Lai Jiangshan <jiangshanlai@...il.com>,
Zqiang <qiang.zhang1211@...il.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
linux-riscv@...ts.infradead.org, Danilo Krummrich <dakr@...nel.org>
Subject: [RFC v2 12/13] rust: add rcu abstraction
From: Wedson Almeida Filho <wedsonaf@...il.com>
Add a simple abstraction to guard critical code sections with an rcu
read lock.
Signed-off-by: Wedson Almeida Filho <wedsonaf@...il.com>
Signed-off-by: Danilo Krummrich <dakr@...nel.org>
---
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 f4a94833b29d..65951245879f 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -18,6 +18,7 @@
#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 <linux/rcupdate.h>
+
+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 0d0b19441ae8..f5a413e1ce30 100644
--- a/rust/kernel/sync.rs
+++ b/rust/kernel/sync.rs
@@ -13,6 +13,7 @@
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()
+}
--
2.45.2
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