mac80211: Use queue_lock() in ieee80211_ht_agg_queue_remove().

qdisc_root_lock() is only %100 safe to use when the RTNL
semaphore is held.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/mac80211/wme.c

@@ -241,12 +241,14 @@ void ieee80211_ht_agg_queue_remove(struct ieee80211_local *local,
 	} else {
 		struct netdev_queue *txq;
 		spinlock_t *root_lock;
+		struct Qdisc *q;
 
 		txq = netdev_get_tx_queue(local->mdev, agg_queue);
-		root_lock = qdisc_root_lock(txq->qdisc);
+		q = rcu_dereference(txq->qdisc);
+		root_lock = qdisc_lock(q);
 
 		spin_lock_bh(root_lock);
-		qdisc_reset(txq->qdisc);
+		qdisc_reset(q);
 		spin_unlock_bh(root_lock);
 	}
 }