From 41e44c8df66acdd4d0237205192314ae42f0e5cc Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Mon, 5 Jul 2021 17:10:07 +0100
Subject: [PATCH 1/2] Provide MutexGuard::mutex()

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 tokio/src/sync/mutex.rs | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tokio/src/sync/mutex.rs b/tokio/src/sync/mutex.rs
index 9fd7c912b6d..34eba1386d3 100644
--- a/tokio/src/sync/mutex.rs
+++ b/tokio/src/sync/mutex.rs
@@ -561,6 +561,32 @@ impl<'a, T: ?Sized> MutexGuard<'a, T> {
             marker: marker::PhantomData,
         })
     }
+
+    /// Returns a reference to the original `Mutex`.
+    ///
+    /// ```
+    /// use tokio::sync::{Mutex, MutexGuard};
+    ///
+    /// async fn unlock_and_relock<'l>(guard: MutexGuard<'l, u32>) -> MutexGuard<'l, u32> {
+    ///     println!("1. contains: {:?}", *guard);
+    ///     let mutex = MutexGuard::mutex(&guard);
+    ///     drop(guard);
+    ///     let guard = mutex.lock().await;
+    ///     println!("2. contains: {:?}", *guard);
+    ///     guard
+    /// }
+    /// #
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// #     let mutex = Mutex::new(0u32);
+    /// #     let guard = mutex.lock().await;
+    /// #     unlock_and_relock(guard).await;
+    /// # }
+    /// ```
+    #[inline]
+    pub fn mutex(this: &Self) -> &'a Mutex<T> {
+        this.lock
+    }
 }
 
 impl<T: ?Sized> Drop for MutexGuard<'_, T> {

From 5aa6958b38d4c88cf69cf942590ee885d5791596 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Mon, 5 Jul 2021 17:32:26 +0100
Subject: [PATCH 2/2] Provide OwnedMutexGuard::mutex()

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 tokio/src/sync/mutex.rs | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/tokio/src/sync/mutex.rs b/tokio/src/sync/mutex.rs
index 34eba1386d3..e5ccf7145e6 100644
--- a/tokio/src/sync/mutex.rs
+++ b/tokio/src/sync/mutex.rs
@@ -622,6 +622,35 @@ impl<T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'_, T> {
 
 // === impl OwnedMutexGuard ===
 
+impl<T: ?Sized> OwnedMutexGuard<T> {
+    /// Returns a reference to the original `Arc<Mutex>`.
+    ///
+    /// ```
+    /// use std::sync::Arc;
+    /// use tokio::sync::{Mutex, OwnedMutexGuard};
+    ///
+    /// async fn unlock_and_relock(guard: OwnedMutexGuard<u32>) -> OwnedMutexGuard<u32> {
+    ///     println!("1. contains: {:?}", *guard);
+    ///     let mutex: Arc<Mutex<u32>> = OwnedMutexGuard::mutex(&guard).clone();
+    ///     drop(guard);
+    ///     let guard = mutex.lock_owned().await;
+    ///     println!("2. contains: {:?}", *guard);
+    ///     guard
+    /// }
+    /// #
+    /// # #[tokio::main]
+    /// # async fn main() {
+    /// #     let mutex = Arc::new(Mutex::new(0u32));
+    /// #     let guard = mutex.lock_owned().await;
+    /// #     unlock_and_relock(guard).await;
+    /// # }
+    /// ```
+    #[inline]
+    pub fn mutex(this: &Self) -> &Arc<Mutex<T>> {
+        &this.lock
+    }
+}
+
 impl<T: ?Sized> Drop for OwnedMutexGuard<T> {
     fn drop(&mut self) {
         self.lock.s.release(1)