Re: [PATCH v3] virtio_net: avoid using netif_tx_disable() for serializing tx routine
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2018-10-17 15:09:24
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On Wed, Oct 17, 2018 at 07:44:12PM +0900, Ake Koomsin wrote:
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 <redacted>Acked-by: Michael S. Tsirkin <mst@redhat.com> Thanks a lot for debugging! Seems like stable material to me, right?
quoted hunk ↗ jump to hunk
--- 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 3f5aa59c37b7..3e2c041d76ac 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c@@ -2267,8 +2267,9 @@ 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)) {@@ -2304,7 +2305,9 @@ 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; }-- 2.19.1