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

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Date:   Tue, 5 Jul 2022 09:59:35 +0800
From:   Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Johannes Berg <johannes@...solutions.net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        Vadim Pasternak <vadimp@...dia.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Cornelia Huck <cohuck@...hat.com>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Eric Farman <farman@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        linux-um@...ts.infradead.org, netdev@...r.kernel.org,
        platform-driver-x86@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, bpf@...r.kernel.org,
        kangjie.xu@...ux.alibaba.com,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v11 38/40] virtio_net: support rx queue resize

On Mon, 4 Jul 2022 11:44:12 +0800, Jason Wang <jasowang@...hat.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@...ux.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.

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
>