commit 057d977aed600843dd4a617dca7098555d79110b
author Hiroshi Yamauchi <yamauchi@google.com> Fri Feb 17 15:33:23 2017 -0800
committer Hiroshi Yamauchi <yamauchi@google.com> Tue Feb 21 13:50:11 2017 -0800
tree 1af506ef9e3ae36d44c355b0baa49b362d976f83
parent 6a669aac63ffc17b5e903aa4a1f285fe338eadcf

Always mark reference referents in transaction mode.

Fix a to-space invariant check failure in EnqueueFinalizerReferences.

Reference processing can be a problem and useless during transaction
because it's not easy to roll back what reference processing does and
there's no daemon threads running (in the unstarted runtime). To avoid
issues, always mark reference referents.

Add a do_atomic_update parameter to MarkHeapReference.

Bug: 35417063
Test: test-art-host with CC/CMS/SS.
Change-Id: If32eba8fca19ef86e5d13f7925d179c8aecb9e27

runtime/gc/reference_queue.cc

diff --git a/runtime/gc/reference_queue.cc b/runtime/gc/reference_queue.cc
index 734caea..fd5dcf9 100644
--- a/runtime/gc/reference_queue.cc
+++ b/runtime/gc/reference_queue.cc
@@ -67,6 +67,11 @@
     list_->SetPendingNext(next);
   }
   ref->SetPendingNext(nullptr);
+  return ref;
+}
+
+// This must be called whenever DequeuePendingReference is called.
+void ReferenceQueue::DisableReadBarrierForReference(ObjPtr<mirror::Reference> ref) {
   Heap* heap = Runtime::Current()->GetHeap();
   if (kUseBakerOrBrooksReadBarrier && heap->CurrentCollectorType() == kCollectorTypeCC &&
       heap->ConcurrentCopyingCollector()->IsActive()) {
@@ -92,7 +97,6 @@
       }
     }
   }
-  return ref;
 }
 
 void ReferenceQueue::Dump(std::ostream& os) const {
@@ -140,6 +144,9 @@
       }
       cleared_references->EnqueueReference(ref);
     }
+    // Delay disabling the read barrier until here so that the ClearReferent call above in
+    // transaction mode will trigger the read barrier.
+    DisableReadBarrierForReference(ref);
   }
 }
 
@@ -162,6 +169,9 @@
       }
       cleared_references->EnqueueReference(ref);
     }
+    // Delay disabling the read barrier until here so that the ClearReferent call above in
+    // transaction mode will trigger the read barrier.
+    DisableReadBarrierForReference(ref->AsReference());
   }
 }
 
@@ -174,7 +184,9 @@
   do {
     mirror::HeapReference<mirror::Object>* referent_addr = ref->GetReferentReferenceAddr();
     if (referent_addr->AsMirrorPtr() != nullptr) {
-      visitor->MarkHeapReference(referent_addr);
+      // do_atomic_update is false because mutators can't access the referent due to the weak ref
+      // access blocking.
+      visitor->MarkHeapReference(referent_addr, /*do_atomic_update*/ false);
     }
     ref = ref->GetPendingNext();
   } while (LIKELY(ref != head));