Re: [PATCH] net: ftgmac100: Ensure tx descriptor updates are visible

[Joel Stanley]

On Thu, 22 Aug 2024 at 17:00, Jacky Chou <jacky_chou@xxxxxxxxxxxxxx> wrote:
>
> 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.

Thanks for re-submitting my patch and getting it merged. In the
future, it would be best if you left the authorship, and preserved my
commit message.

 https://lore.kernel.org/all/20201020220639.130696-1-joel@xxxxxxxxx/

Cheers,

Joel

>
> Signed-off-by: Jacky Chou <jacky_chou@xxxxxxxxxxxxxx>
> ---
>  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 93862b027be0..9c521d0af7ac 100644
> --- a/drivers/net/ethernet/faraday/ftgmac100.c
> +++ b/drivers/net/ethernet/faraday/ftgmac100.c
> @@ -582,7 +582,7 @@ 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);
> @@ -666,6 +666,11 @@ 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;
> @@ -819,6 +824,11 @@ 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;
>
> @@ -839,7 +849,7 @@ 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");
>
> @@ -861,7 +871,7 @@ 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++;
> @@ -1354,7 +1364,7 @@ static void ftgmac100_reset(struct ftgmac100 *priv)
>         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)
> @@ -1554,15 +1564,15 @@ 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;
> --
> 2.25.1
>
>