| Message ID | 20241022213221.2383-7-dakr@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | Device / Driver PCI / Platform Rust abstractions | expand |
On Tue, Oct 22, 2024 at 11:33 PM Danilo Krummrich <dakr@kernel.org> wrote: > > From: Wedson Almeida Filho <wedsonaf@gmail.com> > > Add a simple abstraction to guard critical code sections with an rcu > read lock. > > Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com> > Signed-off-by: Danilo Krummrich <dakr@kernel.org> Reviewed-by: Alice Ryhl <aliceryhl@google.com> > 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 <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 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 ()>, Once 6.13 is released, you'll want to use NotThreadSafe here instead of PhantomData. It's landing upstream through vfs.rust.file. Alice
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 <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 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() +}