netdev - [PATCH AUTOSEL 5.8 01/24] net: lantiq: Add locking for TX DMA channel

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Message-Id: <20201012190239.3279198-1-sashal@kernel.org>
Date:   Mon, 12 Oct 2020 15:02:16 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Hauke Mehrtens <hauke@...ke-m.de>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.8 01/24] net: lantiq: Add locking for TX DMA channel

From: Hauke Mehrtens <hauke@...ke-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 <hauke@...ke-m.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.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 635ff3a5dcfb3..51ed8a54d3801 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