Re: [PATCH net-next 1/2] virtio-net: correctly update XDP_TX counters

[Jason Wang]

On 2018å07æ31æ 17:57, Toshiaki Makita wrote:
> On 2018/07/31 18:43, Jason Wang wrote:
> > Commit 5b8f3c8d30a6 ("virtio_net: Add XDP related stats") tries to
> > count TX XDP stats in virtnet_receive(). This will cause several
> > issues:
> >
> > - virtnet_xdp_sq() was called without checking whether or not XDP is
> >    set. This may cause out of bound access when there's no enough txq
> >    for XDP.
> > - Stats were updated even if there's no XDP/XDP_TX.>
> > Fixing this by reusing virtnet_xdp_xmit() for XDP_TX which can counts
> > TX XDP counter itself and remove the unnecessary tx stats embedded in
> > rx stats.
> Thanks for fixing this.
> I wanted to avoid calling u64_stats_update_begin() (i.e. smp_wmb() in 32
> bit systems) for every packet. So I'd like to keep sq stats in
> virtnet_rx_stats.

We can optimize this by adding batching on top. (virtnet_xdp_xmit() 
accepts an array of xdp frames). If you like, please send a patch for this.

Thanks