Merge "Allow WiFi components to manage interface up state"

core/java/android/net/InterfaceConfiguration.java

@@ -80,6 +80,14 @@ public class InterfaceConfiguration implements Parcelable {
         mFlags.add(FLAG_DOWN);
     }
 
+    /**
+     * Set flags so that no changes will be made to the up/down status.
+     */
+    public void ignoreInterfaceUpDownStatus() {
+        mFlags.remove(FLAG_UP);
+        mFlags.remove(FLAG_DOWN);
+    }
+
     public LinkAddress getLinkAddress() {
         return mAddr;
     }

services/core/java/com/android/server/connectivity/tethering/TetherInterfaceStateMachine.java

@@ -136,10 +136,17 @@ public class TetherInterfaceStateMachine extends StateMachine {
             if (ifcg != null) {
                 InetAddress addr = NetworkUtils.numericToInetAddress(ipAsString);
                 ifcg.setLinkAddress(new LinkAddress(addr, prefixLen));
-                if (enabled) {
-                    ifcg.setInterfaceUp();
+                if (mInterfaceType == ConnectivityManager.TETHERING_WIFI) {
+                    // The WiFi stack has ownership of the interface up/down state.
+                    // It is unclear whether the bluetooth or USB stacks will manage their own
+                    // state.
+                    ifcg.ignoreInterfaceUpDownStatus();
                 } else {
-                    ifcg.setInterfaceDown();
+                    if (enabled) {
+                        ifcg.setInterfaceUp();
+                    } else {
+                        ifcg.setInterfaceDown();
+                    }
                 }
                 ifcg.clearFlag("running");
                 mNMService.setInterfaceConfig(mIfaceName, ifcg);