Commit d3d9e484 authored by Auke Kok's avatar Auke Kok Committed by Auke Kok
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e1000: Redo netpoll fix to address community concerns 



The original suggested fix for netpoll was found to be racy on SMP
kernels. While it is highly unlikely that this race would ever be seen
in the real world due to current netpoll usage models, we implemented
this updated fix to address concerns.

Signed-off-by: default avatarMitch Williams <mitch.a.williams@intel.com>
Signed-off-by: default avatarAuke Kok <auke-jan.h.kok@intel.com>
parent 22e11703

drivers/net/e1000/e1000_main.c

+15 −22
Original line number Diff line number Diff line
@@ -3387,8 +3387,8 @@ e1000_intr(int irq, void *data, struct pt_regs *regs) 
		E1000_WRITE_REG(hw, IMC, ~0);

		E1000_WRITE_FLUSH(hw);

	}

	if (likely(netif_rx_schedule_prep(&adapter->polling_netdev[0])))

		__netif_rx_schedule(&adapter->polling_netdev[0]);

	if (likely(netif_rx_schedule_prep(netdev)))

		__netif_rx_schedule(netdev);

	else

		e1000_irq_enable(adapter);

#else
@@ -3431,21 +3431,15 @@ e1000_clean(struct net_device *poll_dev, int *budget) 
{

	struct e1000_adapter *adapter;

	int work_to_do = min(*budget, poll_dev->quota);

	int tx_cleaned = 0, i = 0, work_done = 0;

	int tx_cleaned = 0, work_done = 0;



	/* Must NOT use netdev_priv macro here. */

	adapter = poll_dev->priv;



	/* Keep link state information with original netdev */

	if (!netif_carrier_ok(adapter->netdev))

	if (!netif_carrier_ok(poll_dev))

		goto quit_polling;



	while (poll_dev != &adapter->polling_netdev[i]) {

		i++;

		BUG_ON(i == adapter->num_rx_queues);

	}



	if (likely(adapter->num_tx_queues == 1)) {

	/* e1000_clean is called per-cpu.  This lock protects

	 * tx_ring[0] from being cleaned by multiple cpus

	 * simultaneously.  A failure obtaining the lock means
@@ -3455,10 +3449,8 @@ e1000_clean(struct net_device *poll_dev, int *budget) 
		                                &adapter->tx_ring[0]);

		spin_unlock(&adapter->tx_queue_lock);

	}

	} else

		tx_cleaned = e1000_clean_tx_irq(adapter, &adapter->tx_ring[i]);



	adapter->clean_rx(adapter, &adapter->rx_ring[i],

	adapter->clean_rx(adapter, &adapter->rx_ring[0],

	                  &work_done, work_to_do);



	*budget -= work_done;
@@ -3466,7 +3458,7 @@ e1000_clean(struct net_device *poll_dev, int *budget) 


	/* If no Tx and not enough Rx work done, exit the polling mode */

	if ((!tx_cleaned && (work_done == 0)) ||

	   !netif_running(adapter->netdev)) {

	   !netif_running(poll_dev)) {

quit_polling:

		netif_rx_complete(poll_dev);

		e1000_irq_enable(adapter);
@@ -4752,6 +4744,7 @@ static void 
e1000_netpoll(struct net_device *netdev)

{

	struct e1000_adapter *adapter = netdev_priv(netdev);



	disable_irq(adapter->pdev->irq);

	e1000_intr(adapter->pdev->irq, netdev, NULL);

	e1000_clean_tx_irq(adapter, adapter->tx_ring);

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