diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index 32773635a4..da3b584fb9 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -2734,84 +2734,73 @@ public class Tethering {
         }
     }
 
-    private IpServer.Callback makeControlCallback() {
-        return new IpServer.Callback() {
-            @Override
-            public void updateInterfaceState(IpServer who, int state, int lastError) {
-                notifyInterfaceStateChange(who, state, lastError);
+    private class ControlCallback extends IpServer.Callback {
+        @Override
+        public void updateInterfaceState(IpServer who, int state, int lastError) {
+            final String iface = who.interfaceName();
+            final TetherState tetherState = mTetherStates.get(iface);
+            if (tetherState != null && tetherState.ipServer.equals(who)) {
+                tetherState.lastState = state;
+                tetherState.lastError = lastError;
+            } else {
+                if (DBG) Log.d(TAG, "got notification from stale iface " + iface);
             }
 
-            @Override
-            public void updateLinkProperties(IpServer who, LinkProperties newLp) {
-                notifyLinkPropertiesChanged(who, newLp);
-            }
+            mLog.log(String.format("OBSERVED iface=%s state=%s error=%s", iface, state, lastError));
 
-            @Override
-            public void dhcpLeasesChanged() {
-                maybeDhcpLeasesChanged();
+            // If TetherMainSM is in ErrorState, TetherMainSM stays there.
+            // Thus we give a chance for TetherMainSM to recover to InitialState
+            // by sending CMD_CLEAR_ERROR
+            if (lastError == TETHER_ERROR_INTERNAL_ERROR) {
+                mTetherMainSM.sendMessage(TetherMainSM.CMD_CLEAR_ERROR, who);
             }
-
-            @Override
-            public void requestEnableTethering(int tetheringType, boolean enabled) {
-                mTetherMainSM.sendMessage(TetherMainSM.EVENT_REQUEST_CHANGE_DOWNSTREAM,
-                        tetheringType, 0, enabled ? Boolean.TRUE : Boolean.FALSE);
+            int which;
+            switch (state) {
+                case IpServer.STATE_UNAVAILABLE:
+                case IpServer.STATE_AVAILABLE:
+                    which = TetherMainSM.EVENT_IFACE_SERVING_STATE_INACTIVE;
+                    break;
+                case IpServer.STATE_TETHERED:
+                case IpServer.STATE_LOCAL_ONLY:
+                    which = TetherMainSM.EVENT_IFACE_SERVING_STATE_ACTIVE;
+                    break;
+                default:
+                    Log.wtf(TAG, "Unknown interface state: " + state);
+                    return;
             }
-        };
-    }
-
-    // TODO: Move into TetherMainSM.
-    private void notifyInterfaceStateChange(IpServer who, int state, int error) {
-        final String iface = who.interfaceName();
-        final TetherState tetherState = mTetherStates.get(iface);
-        if (tetherState != null && tetherState.ipServer.equals(who)) {
-            tetherState.lastState = state;
-            tetherState.lastError = error;
-        } else {
-            if (DBG) Log.d(TAG, "got notification from stale iface " + iface);
+            mTetherMainSM.sendMessage(which, state, 0, who);
+            sendTetherStateChangedBroadcast();
         }
 
-        mLog.log(String.format("OBSERVED iface=%s state=%s error=%s", iface, state, error));
-
-        // If TetherMainSM is in ErrorState, TetherMainSM stays there.
-        // Thus we give a chance for TetherMainSM to recover to InitialState
-        // by sending CMD_CLEAR_ERROR
-        if (error == TETHER_ERROR_INTERNAL_ERROR) {
-            mTetherMainSM.sendMessage(TetherMainSM.CMD_CLEAR_ERROR, who);
-        }
-        int which;
-        switch (state) {
-            case IpServer.STATE_UNAVAILABLE:
-            case IpServer.STATE_AVAILABLE:
-                which = TetherMainSM.EVENT_IFACE_SERVING_STATE_INACTIVE;
-                break;
-            case IpServer.STATE_TETHERED:
-            case IpServer.STATE_LOCAL_ONLY:
-                which = TetherMainSM.EVENT_IFACE_SERVING_STATE_ACTIVE;
-                break;
-            default:
-                Log.wtf(TAG, "Unknown interface state: " + state);
+        @Override
+        public void updateLinkProperties(IpServer who, LinkProperties newLp) {
+            final String iface = who.interfaceName();
+            final int state;
+            final TetherState tetherState = mTetherStates.get(iface);
+            if (tetherState != null && tetherState.ipServer.equals(who)) {
+                state = tetherState.lastState;
+            } else {
+                mLog.log("got notification from stale iface " + iface);
                 return;
-        }
-        mTetherMainSM.sendMessage(which, state, 0, who);
-        sendTetherStateChangedBroadcast();
-    }
+            }
 
-    private void notifyLinkPropertiesChanged(IpServer who, LinkProperties newLp) {
-        final String iface = who.interfaceName();
-        final int state;
-        final TetherState tetherState = mTetherStates.get(iface);
-        if (tetherState != null && tetherState.ipServer.equals(who)) {
-            state = tetherState.lastState;
-        } else {
-            mLog.log("got notification from stale iface " + iface);
-            return;
+            mLog.log(String.format(
+                    "OBSERVED LinkProperties update iface=%s state=%s lp=%s",
+                    iface, IpServer.getStateString(state), newLp));
+            final int which = TetherMainSM.EVENT_IFACE_UPDATE_LINKPROPERTIES;
+            mTetherMainSM.sendMessage(which, state, 0, newLp);
         }
 
-        mLog.log(String.format(
-                "OBSERVED LinkProperties update iface=%s state=%s lp=%s",
-                iface, IpServer.getStateString(state), newLp));
-        final int which = TetherMainSM.EVENT_IFACE_UPDATE_LINKPROPERTIES;
-        mTetherMainSM.sendMessage(which, state, 0, newLp);
+        @Override
+        public void dhcpLeasesChanged() {
+            maybeDhcpLeasesChanged();
+        }
+
+        @Override
+        public void requestEnableTethering(int tetheringType, boolean enabled) {
+            mTetherMainSM.sendMessage(TetherMainSM.EVENT_REQUEST_CHANGE_DOWNSTREAM,
+                    tetheringType, 0, enabled ? Boolean.TRUE : Boolean.FALSE);
+        }
     }
 
     private boolean hasSystemFeature(final String feature) {
@@ -2853,7 +2842,7 @@ public class Tethering {
         mLog.i("adding IpServer for: " + iface);
         final TetherState tetherState = new TetherState(
                 new IpServer(iface, mHandler, interfaceType, mLog, mNetd, mBpfCoordinator,
-                        mRoutingCoordinator, makeControlCallback(), mConfig,
+                        mRoutingCoordinator, new ControlCallback(), mConfig,
                         mPrivateAddressCoordinator, mTetheringMetrics,
                         mDeps.getIpServerDependencies()), isNcm);
         mTetherStates.put(iface, tetherState);