mt76: add rcu locking in tid reorder function

Avoids having the tid or station entry disappear prematurely.
Also cancel the reorder work earlier to avoid further processing delayed
by waiting for the lock to be released

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt76/agg-rx.c

@@ -103,6 +103,7 @@ mt76_rx_aggr_reorder_work(struct work_struct *work)
 	__skb_queue_head_init(&frames);
 
 	local_bh_disable();
+	rcu_read_lock();
 
 	spin_lock(&tid->lock);
 	mt76_rx_aggr_check_release(tid, &frames);
@@ -114,6 +115,7 @@ mt76_rx_aggr_reorder_work(struct work_struct *work)
 					     REORDER_TIMEOUT);
 	mt76_rx_complete(dev, &frames, -1);
 
+	rcu_read_unlock();
 	local_bh_enable();
 }
 
@@ -266,6 +268,8 @@ static void mt76_rx_aggr_shutdown(struct mt76_dev *dev, struct mt76_rx_tid *tid)
 	u8 size = tid->size;
 	int i;
 
+	cancel_delayed_work(&tid->reorder_work);
+
 	spin_lock_bh(&tid->lock);
 
 	tid->stopped = true;
@@ -280,8 +284,6 @@ static void mt76_rx_aggr_shutdown(struct mt76_dev *dev, struct mt76_rx_tid *tid)
 	}
 
 	spin_unlock_bh(&tid->lock);
-
-	cancel_delayed_work(&tid->reorder_work);
 }
 
 void mt76_rx_aggr_stop(struct mt76_dev *dev, struct mt76_wcid *wcid, u8 tidno)