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

Jason Wang
2022-07-18T08:56:49Z

On Fri, Jul 15, 2022 at 4:37 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> On Fri, 8 Jul 2022 14:20:52 +0800, Jason Wang <jasowang@redhat.com> wrote:
> > On Tue, Jul 5, 2022 at 10:00 AM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
> > >
> > > On Mon, 4 Jul 2022 11:44:12 +0800, Jason Wang <jasowang@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@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
> >
> > ?
>
> Yes, but I don't think there are any negative effects.

An infinite wait on the napi_disable()?

Thanks

>
> Thanks.
>
> >
> > 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
> > > >
> > >
> >
>