Merge "Simplify the return condition in stop()"

service/src/com/android/server/connectivity/KeepaliveTracker.java

@@ -373,12 +373,10 @@ public class KeepaliveTracker {
                     Log.e(TAG, "Cannot stop unowned keepalive " + mSlot + " on " + mNai.network);
                 }
             }
-            // Ignore the case when the network disconnects immediately after stop() has been
-            // called and the keepalive code is waiting for the response from the modem. This
-            // might happen when the caller listens for a lower-layer network disconnect
-            // callback and stop the keepalive at that time. But the stop() races with the
-            // stop() generated in ConnectivityService network disconnection code path.
-            if (mStartedState == STOPPING && reason == ERROR_INVALID_NETWORK) return;
+            // To prevent races from re-entrance of stop(), return if the state is already stopping.
+            // This might happen if multiple event sources stop keepalive in a short time. Such as
+            // network disconnect after user calls stop(), or tear down socket after binder died.
+            if (mStartedState == STOPPING) return;
 
             // Store the reason of stopping, and report it after the keepalive is fully stopped.
             if (mStopReason != ERROR_STOP_REASON_UNINITIALIZED) {

tests/unit/java/com/android/server/ConnectivityServiceTest.java

@@ -5450,6 +5450,8 @@ public class ConnectivityServiceTest {
             // the follow-up network disconnection will be processed first.
             mWiFiNetworkAgent.setKeepaliveResponseDelay(3 * TIMEOUT_MS);
             ka.stop();
+            // Call stop() twice shouldn't result in crash, b/182586681.
+            ka.stop();
 
             // Make sure the stop has been processed. Wait for executor idle is needed to prevent
             // flaky since the actual stop call to the service is delegated to executor thread.