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List: xen-devel
Subject: [Xen-devel] Re: [PATCH] net: xen-netback: correctly restart Tx
From: Ian Campbell <Ian.Campbell () eu ! citrix ! com>
Date: 2011-09-30 16:45:05
Message-ID: 1317401105.26672.319.camel () zakaz ! uk ! xensource ! com
[Download RAW message or body]
On Fri, 2011-09-30 at 17:37 +0100, David Vrabel wrote:
> If a VM is saved and restored (or migrated) the netback driver will no
> longer process any Tx packets from the frontend. xenvif_up() does not
> schedule the processing of any pending Tx requests from the front end
> because the carrier is off. Without this initial kick the frontend
> just adds Tx requests to the ring without raising an event (until the
> ring is full).
>
> This was caused by 47103041e91794acdbc6165da0ae288d844c820b (net:
> xen-netback: convert to hw_features) which reordered the calls to
> xenvif_up() and netif_carrier_on() in xenvif_connect().
Ah, so the bit of that patch which moved "netif_carrier_on(vif->dev);"
should have actually moved the entire block
netif_carrier_on(vif->dev);
if (netif_running(vif->dev))
xenvif_up(vif);
Since it it is logically a single thing. Make sense. Thanks!
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Ian.
> ---
> drivers/net/xen-netback/interface.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index 0ca86f9..1825629 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -327,12 +327,12 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
> xenvif_get(vif);
>
> rtnl_lock();
> - if (netif_running(vif->dev))
> - xenvif_up(vif);
> if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
> dev_set_mtu(vif->dev, ETH_DATA_LEN);
> netdev_update_features(vif->dev);
> netif_carrier_on(vif->dev);
> + if (netif_running(vif->dev))
> + xenvif_up(vif);
> rtnl_unlock();
>
> return 0;
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