From 84ac360445004127c3869ad8a0f0e292030be4f6 Mon Sep 17 00:00:00 2001
From: Matthew Parkinson <mattpark@microsoft.com>
Date: Fri, 17 Dec 2021 12:12:32 +0000
Subject: [PATCH] Make MPSCQ invariant thread-safe

---
 src/mem/remoteallocator.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mem/remoteallocator.h b/src/mem/remoteallocator.h
index b9b1ff6..3c060e6 100644
--- a/src/mem/remoteallocator.h
+++ b/src/mem/remoteallocator.h
@@ -63,7 +63,6 @@ namespace snmalloc
     void invariant()
     {
       SNMALLOC_ASSERT(back != nullptr);
-      SNMALLOC_ASSERT(front != nullptr);
     }
 
     void init(freelist::HeadPtr stub)
@@ -140,6 +139,7 @@ namespace snmalloc
       Cb cb)
     {
       invariant();
+      SNMALLOC_ASSERT(front != nullptr);
 
       // Use back to bound, so we don't handle new entries.
       auto b = back.load(std::memory_order_relaxed);