[PATCH AUTOSEL 4.14 15/19] virtio_net: avoid using netif_tx_disable() for serializing tx routine

Sasha Levin
2018-10-30T13:29:17Z

From: Ake Koomsin <ake@igel.co.jp>

[ Upstream commit 05c998b738fdd3e5d6a257bcacc8f34b6284d795 ]

Commit 713a98d90c5e ("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 713a98d90c5e ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/virtio_net.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 910c46b47769..f528e9ac3413 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1872,8 +1872,9 @@ 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)) {
@@ -1909,7 +1910,9 @@ 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;
}

--
2.17.1