Re: [PATCH net-next] tuntap: XDP_TX can use native XDP

[Jason Wang]

On 2018å03æ14æ 11:37, Michael S. Tsirkin wrote:
> >   			return NULL;
> >   		case XDP_TX:
> > -			xdp_xmit = true;
> > -			/* fall through */
> > +			get_page(alloc_frag->page);
> > +			alloc_frag->offset += buflen;
> > +			if (tun_xdp_xmit(tun->dev, &xdp))
> > +				goto err_redirect;
> > +			tun_xdp_flush(tun->dev);
> Why do we have to flush here though?
> It might be a good idea to document the reason in a code comment.

ndo_xdp_xmit() does not touch doorbell, so we need a ndo_xdp_flush() 
here. It's the assumption of XDP API I think, so not sure it's worth to 
mention it here.

Thanks