Merge "Quick fix for possible deadlock in LMS" into rvc-dev

location/java/android/location/LocationManager.java

@@ -2562,7 +2562,9 @@ public class LocationManager {
             mRemoteCancellationSignal = remoteCancellationSignal;
         }
 
-        public synchronized void cancel() {
+        public void cancel() {
+            ICancellationSignal cancellationSignal;
+            synchronized (this) {
                 mExecutor = null;
                 mConsumer = null;
 
@@ -2571,13 +2573,17 @@ public class LocationManager {
                     mAlarmManager = null;
                 }
 
-            if (mRemoteCancellationSignal != null) {
+                // ensure only one cancel event will go through
+                cancellationSignal = mRemoteCancellationSignal;
+                mRemoteCancellationSignal = null;
+            }
+
+            if (cancellationSignal != null) {
                 try {
-                    mRemoteCancellationSignal.cancel();
+                    cancellationSignal.cancel();
                 } catch (RemoteException e) {
                     // ignore
                 }
-                mRemoteCancellationSignal = null;
             }
         }