Unpoison CrossThreadPersistents

third_party/WebKit/Source/platform/heap/PersistentNode.cpp

Index: third_party/WebKit/Source/platform/heap/PersistentNode.cpp
diff --git a/third_party/WebKit/Source/platform/heap/PersistentNode.cpp b/third_party/WebKit/Source/platform/heap/PersistentNode.cpp
index cb47bcf10b39766b61a1f4f99d3d733d0381e78f..eed3b9ac39f136e44721de494d00f6d15ccae111 100644
--- a/third_party/WebKit/Source/platform/heap/PersistentNode.cpp
+++ b/third_party/WebKit/Source/platform/heap/PersistentNode.cpp
@@ -117,7 +117,7 @@ void PersistentRegion::tracePersistentNodes(Visitor* visitor,
       slots = slots->m_next;
     }
   }
-  ASSERT(persistentCount == m_persistentCount);
+  DCHECK_EQ(persistentCount, m_persistentCount);
 }
 
 bool CrossThreadPersistentRegion::shouldTracePersistentNode(
@@ -173,4 +173,23 @@ void CrossThreadPersistentRegion::prepareForThreadStateTermination(
   }
 }
 
+#if defined(ADDRESS_SANITIZER)
+void CrossThreadPersistentRegion::unpoisonCrossThreadPersistents() {
+  MutexLocker lock(m_mutex);
+  int persistentCount = 0;
+  for (PersistentNodeSlots* slots = m_persistentRegion->m_slots; slots;
+       slots = slots->m_next) {
+    for (int i = 0; i < PersistentNodeSlots::slotCount; ++i) {

[haraken, 2016/10/17 07:32:40]

Maybe can you simply unpoison m_slot[0 : slotCount] in one call, regardless of
whether the slots are unused or not?

[keishi, 2016/10/17 07:43:00]

We are unpoisoning the persistents, not the persistent nodes, so we cannot do it
in one call. We need to call isUnused because if it is true, m_self points to a
PersistentNode instead of a persistent.

[haraken, 2016/10/17 07:49:04]

Ah, thanks, makes sense.

+      const PersistentNode& node = slots->m_slot[i];
+      if (!node.isUnused()) {
+        ASAN_UNPOISON_MEMORY_REGION(node.self(),
+                                    sizeof(CrossThreadPersistent<void*>));
+        ++persistentCount;
+      }
+    }
+  }
+  DCHECK_EQ(persistentCount, m_persistentRegion->m_persistentCount);
+}
+#endif
+
 }  // namespace blink