From fd7194acb3e20a00f2d51ac890a7ac6ad93828d8 Mon Sep 17 00:00:00 2001
From: Tomasz Wasilczyk <twasilczyk@google.com>
Date: Thu, 7 Sep 2017 14:44:40 -0700
Subject: [PATCH] Fix NativeCallbackThread race condition.

Bug: b/65286959
Test: instrumentation
Change-Id: I0086a362b9b916d87118ed478aa8222874df19b1
---
 .../radio/tests/functional/RadioTunerTest.java   | 15 +++++++++++++++
 .../jni/BroadcastRadio/NativeCallbackThread.cpp  | 16 +++++++++++-----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/core/tests/BroadcastRadioTests/src/android/hardware/radio/tests/functional/RadioTunerTest.java b/core/tests/BroadcastRadioTests/src/android/hardware/radio/tests/functional/RadioTunerTest.java
index c70724019edb1..a8d516405ea2a 100644
--- a/core/tests/BroadcastRadioTests/src/android/hardware/radio/tests/functional/RadioTunerTest.java
+++ b/core/tests/BroadcastRadioTests/src/android/hardware/radio/tests/functional/RadioTunerTest.java
@@ -274,6 +274,21 @@ public class RadioTunerTest {
         verify(mCallback, timeout(kTuneCallbackTimeoutMs)).onProgramInfoChanged(any());
     }
 
+    @Test
+    public void testStepLoop() {
+        openTuner();
+
+        for (int i = 0; i < 10; i++) {
+            Log.d(TAG, "step loop iteration " + (i + 1));
+
+            int ret = mRadioTuner.step(RadioTuner.DIRECTION_DOWN, true);
+            assertEquals(RadioManager.STATUS_OK, ret);
+            verify(mCallback, timeout(kTuneCallbackTimeoutMs)).onProgramInfoChanged(any());
+
+            resetCallback();
+        }
+    }
+
     @Test
     public void testTuneAndGetPI() {
         openTuner();
diff --git a/services/core/jni/BroadcastRadio/NativeCallbackThread.cpp b/services/core/jni/BroadcastRadio/NativeCallbackThread.cpp
index 85ec9e07e39e3..81d46f39d84ac 100644
--- a/services/core/jni/BroadcastRadio/NativeCallbackThread.cpp
+++ b/services/core/jni/BroadcastRadio/NativeCallbackThread.cpp
@@ -48,15 +48,19 @@ void NativeCallbackThread::threadLoop() {
         return;
     }
 
-    while (!mExiting) {
-        ALOGV("Waiting for task...");
+    while (true) {
         Task task;
         {
             unique_lock<mutex> lk(mQueueMutex);
-            mQueueCond.wait(lk);
-            if (mExiting) break;
 
-            if (mQueue.empty()) continue;
+            if (mExiting) break;
+            if (mQueue.empty()) {
+                ALOGV("Waiting for task...");
+                mQueueCond.wait(lk);
+                if (mExiting) break;
+                if (mQueue.empty()) continue;
+            }
+
             task = mQueue.front();
             mQueue.pop();
         }
@@ -74,6 +78,7 @@ void NativeCallbackThread::threadLoop() {
     ALOGE_IF(res != JNI_OK, "Couldn't detach thread");
 
     ALOGV("Native callback thread %p finished", this);
+    ALOGD_IF(!mQueue.empty(), "Skipped execution of %zu tasks", mQueue.size());
 }
 
 void NativeCallbackThread::enqueue(const Task &task) {
@@ -84,6 +89,7 @@ void NativeCallbackThread::enqueue(const Task &task) {
         return;
     }
 
+    ALOGV("Adding task to the queue...");
     mQueue.push(task);
     mQueueCond.notify_one();
 }