net: ll_temac: Avoid ndo_start_xmit returning NETDEV_TX_BUSY

As documented in Documentation/networking/driver.rst, the ndo_start_xmit
method must not return NETDEV_TX_BUSY under any normal circumstances, and
as recommended, we simply stop the tx queue in advance, when there is a
risk that the next xmit would cause a NETDEV_TX_BUSY return.

Signed-off-by: Esben Haabendal <esben@geanix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
index cc482ee..9a13953 100644 (file)
--- a/drivers/net/ethernet/xilinx/ll_temac_main.c
+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
@@ -942,6 +942,11 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
        wmb();
        lp->dma_out(lp, TX_TAILDESC_PTR, tail_p); /* DMA start */
 
+       if (temac_check_tx_bd_space(lp, MAX_SKB_FRAGS + 1)) {
+               netdev_info(ndev, "%s -> netif_stop_queue\n", __func__);
+               netif_stop_queue(ndev);
+       }
+
        return NETDEV_TX_OK;
 }