Add thread safety analysis annotations.

Enable thread safety analysis annotations for clang.
See https://clang.llvm.org/docs/ThreadSafetyAnalysis.html
for instructions on using these in the source code.

Bug: 28094863
Test: annotated
frameworks/native/services/inputflinger/InputDispatcher.cpp
and enabled '-Werror' and '-Wthread-safety' clang
compiler flags in Android.bp for inputflinger.
Observed compiler errors when accessing
instance attributes without holding a lock. Also added
a compile test Mutex_test.cpp, which can be build using
m libutils_tests and run using
/data/nativetest64/libutils_tests/libutils_tests

Change-Id: I24ce111241cc339901bc45dda8b446df5299af4a

1 files changed, 32 insertions, 0 deletions

diff --git a/libutils/tests/Mutex_test.cpp b/libutils/tests/Mutex_test.cpp
new file mode 100644
index 000000000..8a1805f51
--- /dev/null
+++ b/libutils/tests/Mutex_test.cpp
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#include <utils/Mutex.h>
+
+#include <gtest/gtest.h>
+
+static android::Mutex mLock;
+static int i GUARDED_BY(mLock);
+
+void modifyLockedVariable() REQUIRES(mLock) {
+    i = 1;
+}
+
+TEST(Mutex, compile) {
+    android::Mutex::Autolock _l(mLock);
+    i = 0;
+    modifyLockedVariable();
+}
\ No newline at end of file