Add exclusion for Reference.clear and reference processing

Prevents race conditions like unclearing cleared references or
calling IsMarkedHeapReference on null references.

Bug: 33389022

Test: test-art-host

Change-Id: Iee83b76d84453e929172f1a83f284aa4910e126c

1 files changed, 7 insertions, 0 deletions

diff --git a/runtime/gc/reference_processor.h b/runtime/gc/reference_processor.h
index 759b7e129c..b15544d549 100644
--- a/runtime/gc/reference_processor.h
+++ b/runtime/gc/reference_processor.h
@@ -73,6 +73,9 @@ class ReferenceProcessor {
       REQUIRES_SHARED(Locks::mutator_lock_)
       REQUIRES(!Locks::reference_processor_lock_,
                !Locks::reference_queue_finalizer_references_lock_);
+  void ClearReferent(ObjPtr<mirror::Reference> ref)
+      REQUIRES_SHARED(Locks::mutator_lock_)
+      REQUIRES(!Locks::reference_processor_lock_);
 
  private:
   bool SlowPathEnabled() REQUIRES_SHARED(Locks::mutator_lock_);
@@ -84,6 +87,10 @@ class ReferenceProcessor {
   // referents.
   void StartPreservingReferences(Thread* self) REQUIRES(!Locks::reference_processor_lock_);
   void StopPreservingReferences(Thread* self) REQUIRES(!Locks::reference_processor_lock_);
+  // Wait until reference processing is done.
+  void WaitUntilDoneProcessingReferences(Thread* self)
+      REQUIRES_SHARED(Locks::mutator_lock_)
+      REQUIRES(Locks::reference_processor_lock_);
   // Collector which is clearing references, used by the GetReferent to return referents which are
   // already marked.
   collector::GarbageCollector* collector_ GUARDED_BY(Locks::reference_processor_lock_);