Commit 05c998b7 authored Oct 17, 2018 by Ake Koomsin Committed by David S. Miller Oct 17, 2018

virtio_net: avoid using netif_tx_disable() for serializing tx routine



Commit 713a98d9 ("virtio-net: serialize tx routine during reset")
introduces netif_tx_disable() after netif_device_detach() in order to
avoid use-after-free of tx queues. However, there are two issues.

1) Its operation is redundant with netif_device_detach() in case the
   interface is running.
2) In case of the interface is not running before suspending and
   resuming, the tx does not get resumed by netif_device_attach().
   This results in losing network connectivity.

It is better to use netif_tx_lock_bh()/netif_tx_unlock_bh() instead for
serializing tx routine during reset. This also preserves the symmetry
of netif_device_detach() and netif_device_attach().

Fixes commit 713a98d9 ("virtio-net: serialize tx routine during reset")
Signed-off-by: Ake Koomsin <ake@igel.co.jp>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 84dad559

drivers/net/virtio_net.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -2218,8 +2218,9 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
		/* Make sure no work handler is accessing the device */
		flush_work(&vi->config_work);

		netif_tx_lock_bh(vi->dev);
		netif_device_detach(vi->dev);
		netif_tx_disable(vi->dev);
		netif_tx_unlock_bh(vi->dev);
		cancel_delayed_work_sync(&vi->refill);

		if (netif_running(vi->dev)) {
		@@ -2255,7 +2256,9 @@ static int virtnet_restore_up(struct virtio_device *vdev)
		}
		}

		netif_tx_lock_bh(vi->dev);
		netif_device_attach(vi->dev);
		netif_tx_unlock_bh(vi->dev);
		return err;
		}

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