[PATCH v11 38/40] virtio_net: support rx queue resize

[Jason Wang]

On Tue, Jul 5, 2022 at 10:00 AM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:
>
> On Mon, 4 Jul 2022 11:44:12 +0800, Jason Wang <jasowang at redhat.com> wrote:
> >
> > 在 2022/6/29 14:56, Xuan Zhuo 写道:
> > > This patch implements the resize function of the rx queues.
> > > Based on this function, it is possible to modify the ring num of the
> > > queue.
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> > > ---
> > >   drivers/net/virtio_net.c | 22 ++++++++++++++++++++++
> > >   1 file changed, 22 insertions(+)
> > >
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index 9fe222a3663a..6ab16fd193e5 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -278,6 +278,8 @@ struct padded_vnet_hdr {
> > >     char padding[12];
> > >   };
> > >
> > > +static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
> > > +
> > >   static bool is_xdp_frame(void *ptr)
> > >   {
> > >     return (unsigned long)ptr & VIRTIO_XDP_FLAG;
> > > @@ -1846,6 +1848,26 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
> > >     return NETDEV_TX_OK;
> > >   }
> > >
> > > +static int virtnet_rx_resize(struct virtnet_info *vi,
> > > +                        struct receive_queue *rq, u32 ring_num)
> > > +{
> > > +   int err, qindex;
> > > +
> > > +   qindex = rq - vi->rq;
> > > +
> > > +   napi_disable(&rq->napi);
> >
> >
> > Do we need to cancel the refill work here?
>
>
> I think no, napi_disable is mutually exclusive, which ensures that there will be
> no conflicts between them.

So this sounds similar to what I've fixed recently.

1) NAPI schedule delayed work.
2) we disable NAPI here
3) delayed work get schedule and call NAPI again

?

Thanks

>
> Thanks.
>
> >
> > Thanks
> >
> >
> > > +
> > > +   err = virtqueue_resize(rq->vq, ring_num, virtnet_rq_free_unused_buf);
> > > +   if (err)
> > > +           netdev_err(vi->dev, "resize rx fail: rx queue index: %d err: %d\n", qindex, err);
> > > +
> > > +   if (!try_fill_recv(vi, rq, GFP_KERNEL))
> > > +           schedule_delayed_work(&vi->refill, 0);
> > > +
> > > +   virtnet_napi_enable(rq->vq, &rq->napi);
> > > +   return err;
> > > +}
> > > +
> > >   /*
> > >    * Send command via the control virtqueue and check status.  Commands
> > >    * supported by the hypervisor, as indicated by feature bits, should
> >
>