Add exclusion between instrumentation and GC
Instrumentation calls VisitClasses while exclusive holding the
mutator lock. This can cause deadlocks since VisitClasses needs to
decode JNI weak globals. If the system weak slow path flag is set,
then we wait holding locks while exclusive holding the mutator lock.
This causes a deadlock since the GC cannot acquire the mutator lock
to sweep system weaks.
This fixes a deadlock seen in one of the tracing tests.
Change-Id: I580152118e068a70f309dcc19df4144afec835dd
diff --git a/runtime/gc/scoped_gc_critical_section.h b/runtime/gc/scoped_gc_critical_section.h
new file mode 100644
index 0000000..ec93bca
--- /dev/null
+++ b/runtime/gc/scoped_gc_critical_section.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_GC_SCOPED_GC_CRITICAL_SECTION_H_
+#define ART_RUNTIME_GC_SCOPED_GC_CRITICAL_SECTION_H_
+
+#include "base/mutex.h"
+#include "collector_type.h"
+#include "gc_cause.h"
+
+namespace art {
+
+class Thread;
+
+namespace gc {
+
+// Wait until the GC is finished and then prevent GC from starting until the destructor. Used
+// to prevent deadlocks in places where we call ClassLinker::VisitClass with all th threads
+// suspended.
+class ScopedGCCriticalSection {
+ public:
+ ScopedGCCriticalSection(Thread* self, GcCause cause, CollectorType collector_type)
+ ACQUIRE(Roles::uninterruptible_);
+ ~ScopedGCCriticalSection() RELEASE(Roles::uninterruptible_);
+
+ private:
+ Thread* const self_;
+ const char* old_cause_;
+};
+
+} // namespace gc
+} // namespace art
+
+#endif // ART_RUNTIME_GC_SCOPED_GC_CRITICAL_SECTION_H_