From d0f50c7aff4be2fe9d3da8df49b0e80c4150a47b Mon Sep 17 00:00:00 2001
From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Tue, 22 Sep 2020 23:41:12 +0200
Subject: [PATCH 6/6] net: lantiq: Add locking for TX DMA channel
Git-commit: f9317ae5523f99999fb54c513ebabbb2bc887ddf
References: git-fixes
Patch-mainline: v5.9

The TX DMA channel data is accessed by the xrx200_start_xmit() and the
xrx200_tx_housekeeping() function from different threads. Make sure the
accesses are synchronized by acquiring the netif_tx_lock() in the
xrx200_tx_housekeeping() function too. This lock is acquired by the
kernel before calling xrx200_start_xmit().

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/ethernet/lantiq_xrx200.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c
index 96948276b2bc..4e44a39267eb 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -245,6 +245,7 @@ static int xrx200_tx_housekeeping(struct napi_struct *napi, int budget)
 	int pkts = 0;
 	int bytes = 0;
 
+	netif_tx_lock(net_dev);
 	while (pkts < budget) {
 		struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->tx_free];
 
@@ -268,6 +269,7 @@ static int xrx200_tx_housekeeping(struct napi_struct *napi, int budget)
 	net_dev->stats.tx_bytes += bytes;
 	netdev_completed_queue(ch->priv->net_dev, pkts, bytes);
 
+	netif_tx_unlock(net_dev);
 	if (netif_queue_stopped(net_dev))
 		netif_wake_queue(net_dev);
 
-- 
2.16.4