mt76: fix concurrent rx calls on A-MPDU release

Add a spinlock in mt76_rx_complete. Without this, multiple stats updates
could happen in parallel, which can lead to deadlocks. There are
probably more corner cases fixed by this change.

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

drivers/net/wireless/mediatek/mt76/mac80211.c

@@ -561,6 +561,7 @@ void mt76_rx_complete(struct mt76_dev *dev, struct sk_buff_head *frames,
 	if (queue >= 0)
 	    napi = &dev->napi[queue];
 
+	spin_lock(&dev->rx_lock);
 	while ((skb = __skb_dequeue(frames)) != NULL) {
 		if (mt76_check_ccmp_pn(skb)) {
 			dev_kfree_skb(skb);
@@ -570,6 +571,7 @@ void mt76_rx_complete(struct mt76_dev *dev, struct sk_buff_head *frames,
 		sta = mt76_rx_convert(skb);
 		ieee80211_rx_napi(dev->hw, sta, skb, napi);
 	}
+	spin_unlock(&dev->rx_lock);
 }
 
 void mt76_rx_poll_complete(struct mt76_dev *dev, enum mt76_rxq_id q)

drivers/net/wireless/mediatek/mt76/mt76.h

@@ -241,6 +241,7 @@ struct mt76_dev {
 	struct device *dev;
 
 	struct net_device napi_dev;
+	spinlock_t rx_lock;
 	struct napi_struct napi[__MT_RXQ_MAX];
 	struct sk_buff_head rx_skb[__MT_RXQ_MAX];
 

drivers/net/wireless/mediatek/mt76/mt76x2_init.c

@@ -645,6 +645,7 @@ struct mt76x2_dev *mt76x2_alloc_device(struct device *pdev)
 	dev->mt76.drv = &drv_ops;
 	mutex_init(&dev->mutex);
 	spin_lock_init(&dev->irq_lock);
+	spin_lock_init(&dev->mt76.rx_lock);
 
 	return dev;
 }