Re: [PATCH net v3] virtio_net: Fix error unwinding of XDP initialization

[Feng Liu]

On 2023-05-05 p.m.10:33, Xuan Zhuo wrote:
> External email: Use caution opening links or attachments
>
>
> On Tue, 2 May 2023 20:35:25 -0400, Feng Liu <feliu@xxxxxxxxxx> wrote:
> > When initializing XDP in virtnet_open(), some rq xdp initialization
> > may hit an error causing net device open failed. However, previous
> > rqs have already initialized XDP and enabled NAPI, which is not the
> > expected behavior. Need to roll back the previous rq initialization
> > to avoid leaks in error unwinding of init code.
> >
> > Also extract a helper function of disable queue pairs, and use newly
> > introduced helper function in error unwinding and virtnet_close;
> >
> > Issue: 3383038
> > Fixes: 754b8a21a96d ("virtio_net: setup xdp_rxq_info")
> > Signed-off-by: Feng Liu <feliu@xxxxxxxxxx>
> > Reviewed-by: William Tu <witu@xxxxxxxxxx>
> > Reviewed-by: Parav Pandit <parav@xxxxxxxxxx>
> > Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
> > Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > Change-Id: Ib4c6a97cb7b837cfa484c593dd43a435c47ea68f
> > ---
> >   drivers/net/virtio_net.c | 30 ++++++++++++++++++++----------
> >   1 file changed, 20 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 8d8038538fc4..3737cf120cb7 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1868,6 +1868,13 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
> >        return received;
> >   }
> >
> > +static void virtnet_disable_qp(struct virtnet_info *vi, int qp_index)
> > +{
> > +     virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
> > +     napi_disable(&vi->rq[qp_index].napi);
> > +     xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
> > +}
> > +
> >   static int virtnet_open(struct net_device *dev)
> >   {
> >        struct virtnet_info *vi = netdev_priv(dev);
> > @@ -1883,20 +1890,26 @@ static int virtnet_open(struct net_device *dev)
> >
> >                err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev, i, vi->rq[i].napi.napi_id);
> >                if (err < 0)
> > -                     return err;
> > +                     goto err_xdp_info_reg;
> >
> >                err = xdp_rxq_info_reg_mem_model(&vi->rq[i].xdp_rxq,
> >                                                 MEM_TYPE_PAGE_SHARED, NULL);
> > -             if (err < 0) {
> > -                     xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
> > -                     return err;
> > -             }
> > +             if (err < 0)
> > +                     goto err_xdp_reg_mem_model;
> >
> >                virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
> >                virtnet_napi_tx_enable(vi, vi->sq[i].vq, &vi->sq[i].napi);
> >        }
> >
> >        return 0;
> > +
> > +err_xdp_reg_mem_model:
> > +     xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
> > +err_xdp_info_reg:
> > +     for (i = i - 1; i >= 0; i--)
> > +             virtnet_disable_qp(vi, i);
>
>
> I would to know should we handle for these:
>
>          disable_delayed_refill(vi);
>          cancel_delayed_work_sync(&vi->refill);
>
>
> Maybe we should call virtnet_close() with "i" directly.
>
> Thanks.
Can’t use i directly here, because if xdp_rxq_info_reg fails, napi has 
not been enabled for current qp yet, I should roll back from the queue 
pairs where napi was enabled before(i--), otherwise it will hang at napi 
disable api

> > +
> > +     return err;
> >   }
> >
> >   static int virtnet_poll_tx(struct napi_struct *napi, int budget)
> > @@ -2305,11 +2318,8 @@ static int virtnet_close(struct net_device *dev)
> >        /* Make sure refill_work doesn't re-enable napi! */
> >        cancel_delayed_work_sync(&vi->refill);
> >
> > -     for (i = 0; i < vi->max_queue_pairs; i++) {
> > -             virtnet_napi_tx_disable(&vi->sq[i].napi);
> > -             napi_disable(&vi->rq[i].napi);
> > -             xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
> > -     }
> > +     for (i = 0; i < vi->max_queue_pairs; i++)
> > +             virtnet_disable_qp(vi, i);
> >
> >        return 0;
> >   }
> > --
> > 2.37.1 (Apple Git-137.1)