From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Wang <jasowang@redhat.com>
Subject: Re: [PATCH v4 net] virtio-net: validate features during probe
Date: Thu, 20 Nov 2014 16:57:16 +0800
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On 11/20/2014 04:27 PM, Jason Wang wrote:
> We currently trigger BUG when VIRTIO_NET_F_CTRL_VQ
> is not set but one of features depending on it is.
> That's not a friendly way to report errors to
> hypervisors.
> Let's check, and fail probe instead.
>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Wanlong Gao <gaowanlong@cn.fujitsu.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> Changes from V1:
> - Drop NETIF_F_*_UFO from checklist
> Changes from V2:
> - only check the features for ctrl vq (this fix the real bug)
> - better error message and simplify API
> Changes from V3:
> - pass dbit directly and even better error message
> - typo fix
> ---
>  drivers/net/virtio_net.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ec2a8b4..cc53ff1 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1673,6 +1673,40 @@ static const struct attribute_group virtio_net_mrg_rx_group = {
>  };
>  #endif
>  
> +static bool virtnet_fail_on_feature(struct virtio_device *vdev,
> +				    unsigned int fbit,
> +				    const char *fname, const char *dname)
> +{
> +	if (!virtio_has_feature(vdev, fbit))
> +		return false;
> +
> +	dev_err(&vdev->dev, "advertise feature %s but not %s",
> +		fname, dname);
> +
> +	return true;
> +}
> +

Michael suggest adding "device" before "advertise", will post V5