Linux Virtualization - Apr 2014 - [PATCH] virtio_net: return error when there is no virtqueue or MQ isn't support

Currently ethtool returns zero if there is no virtqueue or MQ isn't
support, we should return -ENOTSUPP to notice user.

Signed-off-by: Amos Kong <akong at redhat.com>
---
 drivers/net/virtio_net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8a852b5..eaf8266 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1053,7 +1053,7 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16
queue_pairs)
 	struct net_device *dev = vi->dev;
 
 	if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))
-		return 0;
+		return -ENOTSUPP;
 
 	s.virtqueue_pairs = queue_pairs;
 	sg_init_one(&sg, &s, sizeof(s));
-- 
1.9.0

On 04/21/2014 11:11 PM, Amos Kong wrote:
> Currently ethtool returns zero if there is no virtqueue or MQ isn't
> support, we should return -ENOTSUPP to notice user.
>
> Signed-off-by: Amos Kong <akong at redhat.com>
> ---
>  drivers/net/virtio_net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 8a852b5..eaf8266 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1053,7 +1053,7 @@ static int virtnet_set_queues(struct virtnet_info
*vi, u16 queue_pairs)
>  	struct net_device *dev = vi->dev;
>  
>  	if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))
> -		return 0;
> +		return -ENOTSUPP;
>  
>  	s.virtqueue_pairs = queue_pairs;
>  	sg_init_one(&sg, &s, sizeof(s));
How about check the return value of virtnet_set_queues() in
virtnet_restore() also?

On Tue, Apr 22, 2014 at 11:11:50AM +0800, Jason Wang
wrote:
> On 04/21/2014 11:11 PM, Amos Kong wrote:
> > Currently ethtool returns zero if there is no virtqueue or MQ
isn't
> > support, we should return -ENOTSUPP to notice user.
> >
> > Signed-off-by: Amos Kong <akong at redhat.com>
> > ---
> >  drivers/net/virtio_net.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 8a852b5..eaf8266 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1053,7 +1053,7 @@ static int virtnet_set_queues(struct
virtnet_info *vi, u16 queue_pairs)
> >  	struct net_device *dev = vi->dev;
> >  
> >  	if (!vi->has_cvq || !virtio_has_feature(vi->vdev,
VIRTIO_NET_F_MQ))
> > -		return 0;
> > +		return -ENOTSUPP;
> >  
> >  	s.virtqueue_pairs = queue_pairs;
> >  	sg_init_one(&sg, &s, sizeof(s));
> 
> How about check the return value of virtnet_set_queues() in
> virtnet_restore() also?
If we migrate a guest from MQ supported side to MQ non-supported side,
virtnet_restore() will not return error right now.

If we return error when no vq or no mq support, and check return value
of virtnet_set_queues() in virtnet_restore(), migration will fail. 
Is it expected?


-- 
			Amos.