Commit 51158207 authored by Wedson Almeida Filho's avatar Wedson Almeida Filho Committed by Greg Kroah-Hartman
Browse files

rust: add rcu abstraction 



Add a simple abstraction to guard critical code sections with an rcu
read lock.

Reviewed-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarWedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: default avatarDanilo Krummrich <dakr@kernel.org>
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
Tested-by: default avatarDirk Behme <dirk.behme@de.bosch.com>
Tested-by: default avatarFabien Parent <fabien.parent@linaro.org>
Link: https://lore.kernel.org/r/20241219170425.12036-5-dakr@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9b90864b

MAINTAINERS

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@@ -19691,6 +19691,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev 
F:	Documentation/RCU/

F:	include/linux/rcu*

F:	kernel/rcu/

F:	rust/kernel/sync/rcu.rs

X:	Documentation/RCU/torture.rst

X:	include/linux/srcu*.h

X:	kernel/rcu/srcu*.c

rust/helpers/helpers.c

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@@ -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"

rust/helpers/rcu.c

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// 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();

}

rust/kernel/sync.rs

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@@ -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};

rust/kernel/sync/rcu.rs

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// 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()

}