6.15-stable review patch. If anyone has any objections, please let me know.
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From: Danilo Krummrich dakr@kernel.org
commit 20c96ed278e362ae4e324ed7d8c69fb48c508d3c upstream.
We can't expose direct access to the internal Revocable, since this allows users to directly revoke the internal Revocable without Devres having the chance to synchronize with the devres callback -- we have to guarantee that the internal Revocable has been fully revoked before the device is fully unbound.
Hence, remove the corresponding Deref implementation and, instead, provide indirect accessors for the internal Revocable.
Note that we can still support Devres::revoke() by implementing the required synchronization (which would be almost identical to the synchronization in Devres::drop()).
Fixes: 76c01ded724b ("rust: add devres abstraction") Reviewed-by: Benno Lossin lossin@kernel.org Link: https://lore.kernel.org/r/20250611174827.380555-1-dakr@kernel.org Signed-off-by: Danilo Krummrich dakr@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- rust/kernel/devres.rs | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)
--- a/rust/kernel/devres.rs +++ b/rust/kernel/devres.rs @@ -12,13 +12,11 @@ use crate::{ error::{Error, Result}, ffi::c_void, prelude::*, - revocable::Revocable, - sync::{Arc, Completion}, + revocable::{Revocable, RevocableGuard}, + sync::{rcu, Arc, Completion}, types::ARef, };
-use core::ops::Deref; - #[pin_data] struct DevresInner<T> { dev: ARef<Device>, @@ -196,13 +194,15 @@ impl<T> Devres<T> {
Ok(()) } -}
-impl<T> Deref for Devres<T> { - type Target = Revocable<T>; + /// [`Devres`] accessor for [`Revocable::try_access`]. + pub fn try_access(&self) -> Option<RevocableGuard<'_, T>> { + self.0.data.try_access() + }
- fn deref(&self) -> &Self::Target { - &self.0.data + /// [`Devres`] accessor for [`Revocable::try_access_with_guard`]. + pub fn try_access_with_guard<'a>(&'a self, guard: &'a rcu::Guard) -> Option<&'a T> { + self.0.data.try_access_with_guard(guard) } }
@@ -210,7 +210,7 @@ impl<T> Drop for Devres<T> { fn drop(&mut self) { // SAFETY: When `drop` runs, it is guaranteed that nobody is accessing the revocable data // anymore, hence it is safe not to wait for the grace period to finish. - if unsafe { self.revoke_nosync() } { + if unsafe { self.0.data.revoke_nosync() } { // We revoked `self.0.data` before the devres action did, hence try to remove it. if !DevresInner::remove_action(&self.0) { // We could not remove the devres action, which means that it now runs concurrently,