Re: [PATCH 1/2] Revert "e1000e: fix cyclic resets at link up with active tx"

[Oleksandr Natalenko]

On Wed, Apr 17, 2019 at 11:13:16AM +0300, Konstantin Khlebnikov wrote:
> This reverts commit 0f9e980bf5ee1a97e2e401c846b2af989eb21c61.
> 
> That change cased false-positive warning about hardware hang:
> 
> e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
> IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
> e1000e 0000:00:1f.6 eth0: Detected Hardware Unit Hang:
>    TDH                  <0>
>    TDT                  <1>
>    next_to_use          <1>
>    next_to_clean        <0>
> buffer_info[next_to_clean]:
>    time_stamp           <fffba7a7>
>    next_to_watch        <0>
>    jiffies              <fffbb140>
>    next_to_watch.status <0>
> MAC Status             <40080080>
> PHY Status             <7949>
> PHY 1000BASE-T Status  <0>
> PHY Extended Status    <3000>
> PCI Status             <10>
> e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
> 
> Besides warning everything works fine.
> Original issue will be fixed property in following patch.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
> Reported-by: Joseph Yasi <joe.yasi@xxxxxxxxx>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=203175
> ---
>  drivers/net/ethernet/intel/e1000e/netdev.c |   15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
> index 7acc61e4f645..ba96e52aa8d1 100644
> --- a/drivers/net/ethernet/intel/e1000e/netdev.c
> +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
> @@ -5309,13 +5309,8 @@ static void e1000_watchdog_task(struct work_struct *work)
>  			/* 8000ES2LAN requires a Rx packet buffer work-around
>  			 * on link down event; reset the controller to flush
>  			 * the Rx packet buffer.
> -			 *
> -			 * If the link is lost the controller stops DMA, but
> -			 * if there is queued Tx work it cannot be done.  So
> -			 * reset the controller to flush the Tx packet buffers.
>  			 */
> -			if ((adapter->flags & FLAG_RX_NEEDS_RESTART) ||
> -			    e1000_desc_unused(tx_ring) + 1 < tx_ring->count)
> +			if (adapter->flags & FLAG_RX_NEEDS_RESTART)
>  				adapter->flags |= FLAG_RESTART_NOW;
>  			else
>  				pm_schedule_suspend(netdev->dev.parent,
> @@ -5338,6 +5333,14 @@ static void e1000_watchdog_task(struct work_struct *work)
>  	adapter->gotc_old = adapter->stats.gotc;
>  	spin_unlock(&adapter->stats64_lock);
>  
> +	/* If the link is lost the controller stops DMA, but
> +	 * if there is queued Tx work it cannot be done.  So
> +	 * reset the controller to flush the Tx packet buffers.
> +	 */
> +	if (!netif_carrier_ok(netdev) &&
> +	    (e1000_desc_unused(tx_ring) + 1 < tx_ring->count))
> +		adapter->flags |= FLAG_RESTART_NOW;
> +
>  	/* If reset is necessary, do it outside of interrupt context. */
>  	if (adapter->flags & FLAG_RESTART_NOW) {
>  		schedule_work(&adapter->reset_task);
> 

Tested-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxx>

-- 
  Best regards,
    Oleksandr Natalenko (post-factum)
    Senior Software Maintenance Engineer