On Tue, Dec 04, 2012 at 07:07:58PM +0800, Jason Wang wrote:
> This patch implement the ethtool_{set|get}_channels method of ethool to allow
> user to change the number of queues dymaically when the device is running. 
> This
> would let the user to configure it on demand.
> 
> Signed-off-by: Jason Wang <jasow...@redhat.com>
> ---
>  drivers/net/virtio_net.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 44 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 912f5b2..b9f9887 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1589,10 +1589,54 @@ static struct virtio_driver virtio_net_driver = {
>  #endif
>  };
>  
> +/* TODO: Eliminate OOO packets during switching */
> +static int virtnet_set_channels(struct net_device *dev,
> +                             struct ethtool_channels *channels)
> +{
> +     struct virtnet_info *vi = netdev_priv(dev);
> +     u16 queue_pairs = channels->combined_count;
> +     u16 old_queue_pairs = vi->curr_queue_pairs;
> +
> +     /* We don't support separate rx/tx channels.
> +      * We don't allow setting 'other' channels.
> +      */
> +     if (channels->rx_count || channels->tx_count || channels->other_count)
> +             return -EINVAL;
> +
> +     if (queue_pairs > vi->max_queue_pairs)
> +             return -EINVAL;
> +
> +     vi->curr_queue_pairs = queue_pairs;
> +     if (virtnet_set_queues(vi) == 0) {
> +             netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs);
> +             netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);

Just use queue_pairs - it's shorter.

> +
> +             virtnet_set_affinity(vi, true);
> +     } else
> +             vi->curr_queue_pairs = old_queue_pairs;

Should be
        ret = virtnet_set_queues(vi);
        if (ret) {
                vi->curr_queue_pairs = old_queue_pairs;
                return ret;
        }
otherwise we loose error reporting.

Also it's better if virtnet_set_queues
gets queue_pairs as parameter and set curr_queue_pairs
on success.

> +
> +     return 0;
> +}
> +
> +static void virtnet_get_channels(struct net_device *dev,
> +                              struct ethtool_channels *channels)
> +{
> +     struct virtnet_info *vi = netdev_priv(dev);
> +
> +     channels->combined_count = vi->curr_queue_pairs;
> +     channels->max_combined = vi->max_queue_pairs;
> +     channels->max_other = 0;
> +     channels->rx_count = 0;
> +     channels->tx_count = 0;
> +     channels->other_count = 0;
> +}
> +
>  static const struct ethtool_ops virtnet_ethtool_ops = {
>       .get_drvinfo = virtnet_get_drvinfo,
>       .get_link = ethtool_op_get_link,
>       .get_ringparam = virtnet_get_ringparam,
> +     .set_channels = virtnet_set_channels,
> +     .get_channels = virtnet_get_channels,
>  };
>  
>  static int __init init(void)
> -- 
> 1.7.1
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