Re: [PATCH net-next] virito-net: set queues after reset during xdp_set

[Jason Wang]

On 2017å02æ19æ 13:08, Michael S. Tsirkin wrote:
> > > > -	oxdp_qp = vi->xdp_queue_pairs;
> > > > -
> > > >    	/* Changing the headroom in buffers is a disruptive operation because
> > > >    	 * existing buffers must be flushed and reallocated. This will happen
> > > >    	 * when a xdp program is initially added or xdp is disabled by removing
> > > >    	 * the xdp program resulting in number of XDP queues changing.
> > > >    	 */
> > > >    	if (vi->xdp_queue_pairs != xdp_qp) {
> > > > -		vi->xdp_queue_pairs = xdp_qp;
> > > >    		err = virtnet_reset(vi);
> > > > -		if (err)
> > > > +		if (err) {
> > > > +			dev_warn(&dev->dev, "XDP reset failure.\n");
> > > >    			goto virtio_reset_err;
> > > > +		}
> > > > +		vi->xdp_queue_pairs = xdp_qp;
> > > But xdp_queue_pairs is being used to detect if we should allocate the XDP
> > > headroom. If we move it here do we have a set of buffers in the ring without
> > > the proper headroom when we assign the xdp program below?
> > Right, so how about passing xdp_queue_pairs as a parameter to
> > virtnet_reset(). Then virtnet_reset() can set it after _remove_vq_common()
> > but before virtnet_restore_up()?
> >
> > Thanks
> Jason, wouldn't you say it's cleaner to avoid resets?
> Would you be interested in completing this work:
>
> 20170207053455-mutt-send-email-mst@xxxxxxxxxx

Yes, but this seems still need drop packets, is this acceptable?

Thanks