From 4c7d8b2a14de81ace4d8e61cfaeb8eca26f6f68c Mon Sep 17 00:00:00 2001
From: Alice Ryhl <aliceryhl@google.com>
Date: Fri, 10 Apr 2026 09:05:18 +0200
Subject: [PATCH] runtime: use `compare_exchange_weak()` in worker queue
 (#8028)

---
 .../src/runtime/scheduler/multi_thread/queue.rs  | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/tokio/src/runtime/scheduler/multi_thread/queue.rs b/tokio/src/runtime/scheduler/multi_thread/queue.rs
index 39e50eddc..44a66c3a1 100644
--- a/tokio/src/runtime/scheduler/multi_thread/queue.rs
+++ b/tokio/src/runtime/scheduler/multi_thread/queue.rs
@@ -298,7 +298,7 @@ impl<T> Local<T> {
         if self
             .inner
             .head
-            .compare_exchange(
+            .compare_exchange_weak(
                 prev,
                 pack(
                     head.wrapping_add(NUM_TASKS_TAKEN),
@@ -387,7 +387,7 @@ impl<T> Local<T> {
             let res = self
                 .inner
                 .head
-                .compare_exchange(head, next, AcqRel, Acquire);
+                .compare_exchange_weak(head, next, AcqRel, Acquire);
 
             match res {
                 Ok(_) => break real as usize & MASK,
@@ -523,7 +523,7 @@ impl<T> Steal<T> {
             let res = self
                 .0
                 .head
-                .compare_exchange(prev_packed, next_packed, AcqRel, Acquire);
+                .compare_exchange_weak(prev_packed, next_packed, AcqRel, Acquire);
 
             match res {
                 Ok(_) => break n,
@@ -572,17 +572,11 @@ impl<T> Steal<T> {
             let res = self
                 .0
                 .head
-                .compare_exchange(prev_packed, next_packed, AcqRel, Acquire);
+                .compare_exchange_weak(prev_packed, next_packed, AcqRel, Acquire);
 
             match res {
                 Ok(_) => return n,
-                Err(actual) => {
-                    let (actual_steal, actual_real) = unpack(actual);
-
-                    assert_ne!(actual_steal, actual_real);
-
-                    prev_packed = actual;
-                }
+                Err(actual) => prev_packed = actual,
             }
         }
     }