Additional attempts to fix Oops on disconnect, that appear to be successful.
However, some may be extraneous.
The cancel_delayed_work call is probably the most necessary.  The
device_unplugged check may not be necessary.  del_timer_sync may not
be necessary either, but the Oops I was receiving was related to
timers.  Hence the addition.
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
                                              work_set_promisc);
        int ret = 0;
 
+       if (priv->device_unplugged)
+               return;
+
        mutex_lock(&priv->mtx);
 
        priv->mib_buf.type = MIB_LOCAL;
        tasklet_kill(&priv->rx_tasklet);
 
        if (priv->mac80211_registered) {
+               cancel_delayed_work(&priv->dwork_hw_scan);
                flush_workqueue(priv->hw->workqueue);
                ieee80211_unregister_hw(priv->hw);
        }
 
        kfree(priv->bulk_out_buffer);
 
+       del_timer_sync(&ledtrig_tx_timer);
+
        if (priv->rx_skb)
                kfree_skb(priv->rx_skb);