[PATCH AUTOSEL 5.4 6/8] net: ftgmac100: Ensure tx descriptor updates are visible

Sasha Levin
2024-09-03T20:48:30Z

From: Jacky Chou <jacky_chou@aspeedtech.com>

[ Upstream commit 4186c8d9e6af57bab0687b299df10ebd47534a0a ]

The driver must ensure TX descriptor updates are visible
before updating TX pointer and TX clear pointer.

This resolves TX hangs observed on AST2600 when running
iperf3.

Signed-off-by: Jacky Chou <jacky_chou@aspeedtech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/faraday/ftgmac100.c | 26 ++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
index 98e94d914597a..1de25a5a3f13a 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -567,7 +567,7 @@ static bool ftgmac100_rx_packet(struct ftgmac100 *priv, int *processed)
(*processed)++;
return true;

- drop:
+drop:
/* Clean rxdes0 (which resets own bit) */
rxdes->rxdes0 = cpu_to_le32(status & priv->rxdes0_edorr_mask);
priv->rx_pointer = ftgmac100_next_rx_pointer(priv, pointer);
@@ -651,6 +651,11 @@ static bool ftgmac100_tx_complete_packet(struct ftgmac100 *priv)
ftgmac100_free_tx_packet(priv, pointer, skb, txdes, ctl_stat);
txdes->txdes0 = cpu_to_le32(ctl_stat & priv->txdes0_edotr_mask);

+ /* Ensure the descriptor config is visible before setting the tx
+ * pointer.
+ */
+ smp_wmb();
+
priv->tx_clean_pointer = ftgmac100_next_tx_pointer(priv, pointer);

return true;
@@ -804,6 +809,11 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,
dma_wmb();
first->txdes0 = cpu_to_le32(f_ctl_stat);

+ /* Ensure the descriptor config is visible before setting the tx
+ * pointer.
+ */
+ smp_wmb();
+
/* Update next TX pointer */
priv->tx_pointer = pointer;

@@ -824,7 +834,7 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,

return NETDEV_TX_OK;

- dma_err:
+dma_err:
if (net_ratelimit())
netdev_err(netdev, "map tx fragment failed\n");

@@ -846,7 +856,7 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,
* last fragment, so we know ftgmac100_free_tx_packet()
* hasn't freed the skb yet.
*/
- drop:
+drop:
/* Drop the packet */
dev_kfree_skb_any(skb);
netdev->stats.tx_dropped++;
@@ -1418,7 +1428,7 @@ static void ftgmac100_reset_task(struct work_struct *work)
ftgmac100_init_all(priv, true);

netdev_dbg(netdev, "Reset done !\n");
- bail:
+bail:
if (priv->mii_bus)
mutex_unlock(&priv->mii_bus->mdio_lock);
if (netdev->phydev)
@@ -1489,15 +1499,15 @@ static int ftgmac100_open(struct net_device *netdev)

return 0;

- err_ncsi:
+err_ncsi:
napi_disable(&priv->napi);
netif_stop_queue(netdev);
- err_alloc:
+err_alloc:
ftgmac100_free_buffers(priv);
free_irq(netdev->irq, netdev);
- err_irq:
+err_irq:
netif_napi_del(&priv->napi);
- err_hw:
+err_hw:
iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);
ftgmac100_free_rings(priv);
return err;
--
2.43.0