qtnfmac: lock access to h/w in tx path

Fix tx path regression. Lock should be held when queuing packets
to h/w fifos in order to properly handle configurations with
multiple enabled interfaces.
Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/quantenna/qtnfmac/pearl/pcie.c

@@ -661,14 +661,18 @@ static int qtnf_pcie_data_tx(struct qtnf_bus *bus, struct sk_buff *skb)
 	struct qtnf_pcie_bus_priv *priv = (void *)get_bus_priv(bus);
 	dma_addr_t txbd_paddr, skb_paddr;
 	struct qtnf_tx_bd *txbd;
+	unsigned long flags;
 	int len, i;
 	u32 info;
 	int ret = 0;
 
+	spin_lock_irqsave(&priv->tx0_lock, flags);
+
 	if (!qtnf_tx_queue_ready(priv)) {
 		if (skb->dev)
 			netif_stop_queue(skb->dev);
 
+		spin_unlock_irqrestore(&priv->tx0_lock, flags);
 		return NETDEV_TX_BUSY;
 	}
 
@@ -717,8 +721,10 @@ static int qtnf_pcie_data_tx(struct qtnf_bus *bus, struct sk_buff *skb)
 		dev_kfree_skb_any(skb);
 	}
 
-	qtnf_pcie_data_tx_reclaim(priv);
 	priv->tx_done_count++;
+	spin_unlock_irqrestore(&priv->tx0_lock, flags);
+
+	qtnf_pcie_data_tx_reclaim(priv);
 
 	return NETDEV_TX_OK;
 }
@@ -1247,6 +1253,7 @@ static int qtnf_pcie_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	strcpy(bus->fwname, QTN_PCI_PEARL_FW_NAME);
 	init_completion(&bus->request_firmware_complete);
 	mutex_init(&bus->bus_lock);
+	spin_lock_init(&pcie_priv->tx0_lock);
 	spin_lock_init(&pcie_priv->irq_lock);
 	spin_lock_init(&pcie_priv->tx_reclaim_lock);
 

drivers/net/wireless/quantenna/qtnfmac/pearl/pcie_bus_priv.h

@@ -34,6 +34,8 @@ struct qtnf_pcie_bus_priv {
 
 	/* lock for tx reclaim operations */
 	spinlock_t tx_reclaim_lock;
+	/* lock for tx0 operations */
+	spinlock_t tx0_lock;
 	u8 msi_enabled;
 	int mps;