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Date: Wed, 3 Sep 2014 11:52:08 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20140903085208.GA6781@redhat.com>
References: <1409725530-1425-1-git-send-email-jasowang@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] vhost_net: initialize acked_features to a
 safe value during ack
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To: Jason Wang <jasowang@redhat.com>
Cc: qemu-stable@nongnu.org, Andrey Korolyov <andrey@xdel.ru>, qemu-devel@nongnu.org, Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>, Michael Roth <mdroth@linux.vnet.ibm.com>

On Wed, Sep 03, 2014 at 02:25:30PM +0800, Jason Wang wrote:
> commit 2e6d46d77ed328d34a94688da8371bcbe243479b (vhost: add
> vhost_get_features and vhost_ack_features) removes the step that
> initializes the acked_features to backend_features. This will result an
> unexpected value of acked_features which may fail the features setting of
> vhost. This patch fixes it by recover this step.
> 
> Cc: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
> Cc: Andrey Korolyov <andrey@xdel.ru>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Jason Wang <jasowang@redhat.com>

OK I get it and it's correct, but I think it's better to
put the initialization in core vhost code.
Patch sent, could you confirm that it works for you please?

> ---
>  hw/net/vhost_net.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index f87c798..b1d4b1f 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -115,6 +115,7 @@ unsigned vhost_net_get_features(struct vhost_net *net, unsigned features)
>  
>  void vhost_net_ack_features(struct vhost_net *net, unsigned features)
>  {
> +    net->dev.acked_features = net->dev.backend_features;
>      vhost_ack_features(&net->dev, vhost_net_get_feature_bits(net), features);
>  }
>  
> -- 
> 1.8.3.1