Re: [PATCH net v4] virtio_net: Fix error unwinding of XDP initialization

[Feng Liu]

On 2023-05-09 a.m.12:42, Michael S. Tsirkin wrote:
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>
>
> On Mon, May 08, 2023 at 06:27:08PM -0400, Feng Liu 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 helper functions of disable and enable queue pairs.
> > Use newly introduced disable helper function in error unwinding and
> > virtnet_close. Use enable helper function in virtnet_open.
> >
> > Fixes: 754b8a21a96d ("virtio_net: setup xdp_rxq_info")
> > Signed-off-by: Feng Liu <feliu@xxxxxxxxxx>
> > Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
> > ---
> >
> > v3 -> v4
> > feedbacks from Jiri Pirko
> > - Add symmetric helper function virtnet_enable_qp to enable queues.
> > - Error handle:  cleanup current queue pair in virtnet_enable_qp,
> >    and complete the reset queue pairs cleanup in virtnet_open.
> > - Fix coding style.
> > feedbacks from Parav Pandit
> > - Remove redundant debug message and white space.
> >
> > v2 -> v3
> > feedbacks from Michael S. Tsirkin
> > - Remove redundant comment.
> >
> > v1 -> v2
> > feedbacks from Michael S. Tsirkin
> > - squash two patches together.
> >
> > ---
> >   drivers/net/virtio_net.c | 58 ++++++++++++++++++++++++++++------------
> >   1 file changed, 41 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 8d8038538fc4..df7c08048fa7 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1868,6 +1868,38 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
> >        return received;
> >   }
> >
> > +static void virtnet_disable_qp(struct virtnet_info *vi, int qp_index)
>
>
> I am guessing _qp stands for queue pair? Let's call it
> virtnet_disable_queue_pair please, consistently with max_queue_pairs.
Yes, qp stands for queue pair
will do, thanks

> > +{
> > +     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_enable_qp(struct virtnet_info *vi, int qp_index)
>
> Similarly, virtnet_enable_queue_pair
will do, thanks

> > +{
> > +     struct net_device *dev = vi->dev;
> > +     int err;
> > +
> > +     err = xdp_rxq_info_reg(&vi->rq[qp_index].xdp_rxq, dev, qp_index,
> > +                            vi->rq[qp_index].napi.napi_id);
> > +     if (err < 0)
> > +             return err;
> > +
> > +     err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
> > +                                      MEM_TYPE_PAGE_SHARED, NULL);
> > +     if (err < 0)
> > +             goto err_xdp_reg_mem_model;
> > +
> > +     virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
> > +     virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);
> > +
> > +     return 0;
> > +
> > +err_xdp_reg_mem_model:
> > +     xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
> > +     return err;
> > +}
> > +
> >   static int virtnet_open(struct net_device *dev)
> >   {
> >        struct virtnet_info *vi = netdev_priv(dev);
> > @@ -1881,22 +1913,17 @@ static int virtnet_open(struct net_device *dev)
> >                        if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
> >                                schedule_delayed_work(&vi->refill, 0);
> >
> > -             err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev, i, vi->rq[i].napi.napi_id);
> > +             err = virtnet_enable_qp(vi, i);
> >                if (err < 0)
> > -                     return err;
> > -
> > -             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;
> > -             }
> > -
> > -             virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
> > -             virtnet_napi_tx_enable(vi, vi->sq[i].vq, &vi->sq[i].napi);
> > +                     goto err_enable_qp;
> >        }
> >
> >        return 0;
> > +
> > +err_enable_qp:
> > +     for (i--; i >= 0; i--)
> > +             virtnet_disable_qp(vi, i);
> > +     return err;
> >   }
> >
> >   static int virtnet_poll_tx(struct napi_struct *napi, int budget)
> > @@ -2305,11 +2332,8 @@ 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)