Merge tag 'driver-core-6.16-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

Pull driver core fixes from Danilo Krummrich:

 - Fix a race condition in Devres::drop(). This depends on two other
   patches:
     - (Minimal) Rust abstractions for struct completion
     - Let Revocable indicate whether its data is already being revoked

 - Fix Devres to avoid exposing the internal Revocable

 - Add .mailmap entry for Danilo Krummrich

 - Add Madhavan Srinivasan to embargoed-hardware-issues.rst

* tag 'driver-core-6.16-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core:
  Documentation: embargoed-hardware-issues.rst: Add myself for Power
  mailmap: add entry for Danilo Krummrich
  rust: devres: do not dereference to the internal Revocable
  rust: devres: fix race in Devres::drop()
  rust: revocable: indicate whether `data` has been revoked already
  rust: completion: implement initial abstraction

1 files changed, 14 insertions, 4 deletions

diff --git a/rust/kernel/revocable.rs b/rust/kernel/revocable.rs
index db4aa46bb121..06a3cdfce344 100644
--- a/rust/kernel/revocable.rs
+++ b/rust/kernel/revocable.rs
@@ -154,8 +154,10 @@ impl<T> Revocable<T> {
     /// # Safety
     ///
     /// Callers must ensure that there are no more concurrent users of the revocable object.
-    unsafe fn revoke_internal<const SYNC: bool>(&self) {
-        if self.is_available.swap(false, Ordering::Relaxed) {
+    unsafe fn revoke_internal<const SYNC: bool>(&self) -> bool {
+        let revoke = self.is_available.swap(false, Ordering::Relaxed);
+
+        if revoke {
             if SYNC {
                 // SAFETY: Just an FFI call, there are no further requirements.
                 unsafe { bindings::synchronize_rcu() };
@@ -165,6 +167,8 @@ impl<T> Revocable<T> {
             // `compare_exchange` above that takes `is_available` from `true` to `false`.
             unsafe { drop_in_place(self.data.get()) };
         }
+
+        revoke
     }
 
     /// Revokes access to and drops the wrapped object.
@@ -172,10 +176,13 @@ impl<T> Revocable<T> {
     /// Access to the object is revoked immediately to new callers of [`Revocable::try_access`],
     /// expecting that there are no concurrent users of the object.
     ///
+    /// Returns `true` if `&self` has been revoked with this call, `false` if it was revoked
+    /// already.
+    ///
     /// # Safety
     ///
     /// Callers must ensure that there are no more concurrent users of the revocable object.
-    pub unsafe fn revoke_nosync(&self) {
+    pub unsafe fn revoke_nosync(&self) -> bool {
         // SAFETY: By the safety requirement of this function, the caller ensures that nobody is
         // accessing the data anymore and hence we don't have to wait for the grace period to
         // finish.
@@ -189,7 +196,10 @@ impl<T> Revocable<T> {
     /// If there are concurrent users of the object (i.e., ones that called
     /// [`Revocable::try_access`] beforehand and still haven't dropped the returned guard), this
     /// function waits for the concurrent access to complete before dropping the wrapped object.
-    pub fn revoke(&self) {
+    ///
+    /// Returns `true` if `&self` has been revoked with this call, `false` if it was revoked
+    /// already.
+    pub fn revoke(&self) -> bool {
         // SAFETY: By passing `true` we ask `revoke_internal` to wait for the grace period to
         // finish.
         unsafe { self.revoke_internal::<true>() }