[PATCH AUTOSEL 5.4 01/15] net: lantiq: Add locking for TX DMA channel

[Sasha Levin]

From: Hauke Mehrtens <ha...@hauke-m.de>

[ Upstream commit f9317ae5523f99999fb54c513ebabbb2bc887ddf ]

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 <ha...@hauke-m.de>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 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 96948276b2bc3..4e44a39267eb3 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);
 
-- 
2.25.1