IEEE802154_RX_MSG        = 1,
 };
 
+enum ieee802154_sdata_state_bits {
+       SDATA_STATE_RUNNING,
+};
+
 /* Slave interface definition.
  *
  * Slaves represent typical network interfaces available from userspace.
        struct net_device *dev;
 
        int type;
-       bool running;
+       unsigned long state;
 
        spinlock_t mib_lock;
 
        return netdev_priv(dev);
 }
 
+static inline bool
+ieee802154_sdata_running(struct ieee802154_sub_if_data *sdata)
+{
+       return test_bit(SDATA_STATE_RUNNING, &sdata->state);
+}
+
 extern struct ieee802154_reduced_mlme_ops mac802154_mlme_reduced;
 extern struct ieee802154_mlme_ops mac802154_mlme_wpan;
 
 
                mutex_lock(&sdata->local->iflist_mtx);
                list_for_each_entry(subif, &sdata->local->interfaces, list) {
                        if (subif != sdata && subif->type == sdata->type &&
-                           subif->running) {
+                           ieee802154_sdata_running(subif)) {
                                mutex_unlock(&sdata->local->iflist_mtx);
                                return -EBUSY;
                        }
                mutex_unlock(&sdata->local->iflist_mtx);
        }
 
-       mutex_lock(&sdata->local->iflist_mtx);
-       sdata->running = true;
-       mutex_unlock(&sdata->local->iflist_mtx);
+       set_bit(SDATA_STATE_RUNNING, &sdata->state);
 
        if (local->open_count++ == 0) {
                res = drv_start(local);
        netif_start_queue(dev);
        return 0;
 err:
+       /* might already be clear but that doesn't matter */
+       clear_bit(SDATA_STATE_RUNNING, &sdata->state);
        sdata->local->open_count--;
 
        return res;
 
        netif_stop_queue(dev);
 
-       mutex_lock(&sdata->local->iflist_mtx);
-       sdata->running = false;
-       mutex_unlock(&sdata->local->iflist_mtx);
+       clear_bit(SDATA_STATE_RUNNING, &sdata->state);
 
        if (!--local->open_count)
                drv_stop(local);