Merge tag 'ib-mfd-gpio-input-pwm-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd into next

Merge an immutable branch between MFD, GPIO, Input and PWM to resolve
conflicts for the merge window pull request.

1 files changed, 28 insertions, 0 deletions

diff --git a/rust/kernel/revocable.rs b/rust/kernel/revocable.rs
index 1e5a9d25c21b..db4aa46bb121 100644
--- a/rust/kernel/revocable.rs
+++ b/rust/kernel/revocable.rs
@@ -123,6 +123,34 @@ impl<T> Revocable<T> {
         }
     }
 
+    /// Tries to access the wrapped object and run a closure on it while the guard is held.
+    ///
+    /// This is a convenience method to run short non-sleepable code blocks while ensuring the
+    /// guard is dropped afterwards. [`Self::try_access`] carries the risk that the caller will
+    /// forget to explicitly drop that returned guard before calling sleepable code; this method
+    /// adds an extra safety to make sure it doesn't happen.
+    ///
+    /// Returns [`None`] if the object has been revoked and is therefore no longer accessible, or
+    /// the result of the closure wrapped in [`Some`]. If the closure returns a [`Result`] then the
+    /// return type becomes `Option<Result<>>`, which can be inconvenient. Users are encouraged to
+    /// define their own macro that turns the [`Option`] into a proper error code and flattens the
+    /// inner result into it if it makes sense within their subsystem.
+    pub fn try_access_with<R, F: FnOnce(&T) -> R>(&self, f: F) -> Option<R> {
+        self.try_access().map(|t| f(&*t))
+    }
+
+    /// Directly access the revocable wrapped object.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure this [`Revocable`] instance hasn't been revoked and won't be revoked
+    /// as long as the returned `&T` lives.
+    pub unsafe fn access(&self) -> &T {
+        // SAFETY: By the safety requirement of this function it is guaranteed that
+        // `self.data.get()` is a valid pointer to an instance of `T`.
+        unsafe { &*self.data.get() }
+    }
+
     /// # Safety
     ///
     /// Callers must ensure that there are no more concurrent users of the revocable object.