[Xen-devel] Re: [PATCH] net: xen-netback: correctly restart Tx after a VM restore/migrate

[David Miller <davem@xxxxxxxxxxxxx>]

From: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Date: Fri, 30 Sep 2011 17:45:05 +0100

> 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@xxxxxxxxxx>
> 
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Applied, thanks.

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