Re: [PATCH 2/2] e1000e: start network tx queue only when link is up

From: Joseph Yasi
Date: Mon Apr 22 2019 - 20:51:08 EST


On Wed, Apr 17, 2019 at 4:13 AM Konstantin Khlebnikov
<khlebnikov@xxxxxxxxxxxxxx> wrote:
>
> Driver does not want to keep packets in tx queue when link is lost.
> But present code only reset NIC to flush them, but does not prevent
> queuing new packets. Moreover reset sequence itself could generate
> new packets via netconsole and NIC falls into endless reset loop.
>
> This patch wakes tx queue only when NIC is ready to send packets.
>
> This is proper fix for problem addressed by commit 0f9e980bf5ee
> ("e1000e: fix cyclic resets at link up with active tx").
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
> Suggested-by: Alexander Duyck <alexander.duyck@xxxxxxxxx>
Tested-by: Joseph Yasi <joe.yasi@xxxxxxxxx>
> ---
> drivers/net/ethernet/intel/e1000e/netdev.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
> index ba96e52aa8d1..fe643d66aa10 100644
> --- a/drivers/net/ethernet/intel/e1000e/netdev.c
> +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
> @@ -4209,7 +4209,7 @@ void e1000e_up(struct e1000_adapter *adapter)
> e1000_configure_msix(adapter);
> e1000_irq_enable(adapter);
>
> - netif_start_queue(adapter->netdev);
> + /* tx queue started by watchdog timer when link is up */
>
> e1000e_trigger_lsc(adapter);
> }
> @@ -4607,6 +4607,7 @@ int e1000e_open(struct net_device *netdev)
> pm_runtime_get_sync(&pdev->dev);
>
> netif_carrier_off(netdev);
> + netif_stop_queue(netdev);
>
> /* allocate transmit descriptors */
> err = e1000e_setup_tx_resources(adapter->tx_ring);
> @@ -4667,7 +4668,6 @@ int e1000e_open(struct net_device *netdev)
> e1000_irq_enable(adapter);
>
> adapter->tx_hang_recheck = false;
> - netif_start_queue(netdev);
>
> hw->mac.get_link_status = true;
> pm_runtime_put(&pdev->dev);
> @@ -5289,6 +5289,7 @@ static void e1000_watchdog_task(struct work_struct *work)
> if (phy->ops.cfg_on_link_up)
> phy->ops.cfg_on_link_up(hw);
>
> + netif_wake_queue(netdev);
> netif_carrier_on(netdev);
>
> if (!test_bit(__E1000_DOWN, &adapter->state))
> @@ -5302,6 +5303,7 @@ static void e1000_watchdog_task(struct work_struct *work)
> /* Link status message must follow this format */
> pr_info("%s NIC Link is Down\n", adapter->netdev->name);
> netif_carrier_off(netdev);
> + netif_stop_queue(netdev);
> if (!test_bit(__E1000_DOWN, &adapter->state))
> mod_timer(&adapter->phy_info_timer,
> round_jiffies(jiffies + 2 * HZ));
>