merge new embassy changes

1 files changed, 18 insertions, 0 deletions

diff --git a/embassy-sync/src/blocking_mutex/mod.rs b/embassy-sync/src/blocking_mutex/mod.rs
index 8a4a4c642..a41bc3569 100644
--- a/embassy-sync/src/blocking_mutex/mod.rs
+++ b/embassy-sync/src/blocking_mutex/mod.rs
@@ -50,6 +50,23 @@ impl<R: RawMutex, T> Mutex<R, T> {
             f(inner)
         })
     }
+
+    /// Creates a critical section and grants temporary mutable access to the protected data.
+    ///
+    /// # Safety
+    ///
+    /// This method is marked unsafe because calling this method re-entrantly, i.e. within
+    /// another `lock_mut` or `lock` closure, violates Rust's aliasing rules. Calling this
+    /// method at the same time from different tasks is safe. For a safe alternative with
+    /// mutable access that never causes UB, use a `RefCell` in a `Mutex`.
+    pub unsafe fn lock_mut<U>(&self, f: impl FnOnce(&mut T) -> U) -> U {
+        self.raw.lock(|| {
+            let ptr = self.data.get() as *mut T;
+            // Safety: we have exclusive access to the data, as long as this mutex is not locked re-entrantly
+            let inner = unsafe { &mut *ptr };
+            f(inner)
+        })
+    }
 }
 
 impl<R, T> Mutex<R, T> {
@@ -104,6 +121,7 @@ impl<T> Mutex<raw::CriticalSectionRawMutex, T> {
 
 impl<T> Mutex<raw::NoopRawMutex, T> {
     /// Borrows the data
+    #[allow(clippy::should_implement_trait)]
     pub fn borrow(&self) -> &T {
         let ptr = self.data.get() as *const T;
         unsafe { &*ptr }