netdev - [PATCH v2] net: lantiq: Add locking for TX DMA channel

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Date:   Tue, 22 Sep 2020 23:41:12 +0200
From:   Hauke Mehrtens <hauke@...ke-m.de>
To:     davem@...emloft.net
Cc:     kuba@...nel.org, netdev@...r.kernel.org,
        martin.blumenstingl@...glemail.com,
        Hauke Mehrtens <hauke@...ke-m.de>
Subject: [PATCH v2] net: lantiq: Add locking for TX DMA channel

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@...ke-m.de>
---
 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 affec78cc0f5..36847ff93918 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -239,6 +239,7 @@ 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];
 
@@ -262,6 +263,7 @@ 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);
 
-- 
2.20.1