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)
> +{
> + 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)
> +{
> + 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);
Is it really necessary to call 'xdp_rxq_info_unreg()' from here?
It seems there is a risk of calling that function twice if 'xdp_rxq_info_reg_mem_model()" fails.
For example in the following scenario:
1. We call 'virtnet_enable_qp()' from 'virtnet_open()'
2. 'xdp_rxq_info_reg()' succeeds.
3. 'xdp_rxq_info_reg_mem_model()' fails, so we go to the label "err_xdp_info_reg_mem_model".
4. 'xdp_rxq_info_unreg()' is called.
5. Register state of 'xdp_rxq' changes to 'REG_STATE_UNREGISTERED'.
6. 'virtnet_enable_qp()' returns an error.
7. In 'virtnet_open()' we go to the "err_enable_qp" label.
8. 'virtnet_disable_qp()' is called.
9. 'xdp_rxq_info_unreg()' is called for the second time on the xdp_rxq which is already
in state 'REG_STATE_UNREGISTERED'.
10. The following warning from 'xdp_rxq_info_unreg_mem_model' can be displayed:
if (xdp_rxq->reg_state != REG_STATE_REGISTERED)
{
WARN(1, "Missing register, driver bug");
return;
}
I think the 'xdp_rxq_info_unreg()' can be called only once for the same 'xdp_rxq'.
I believe we should either:
- remove that call from 'virtnet_enable_qp()',
- or use the following API in 'virtnet_disable_qp()':
'xdp_rxq_info_is_reg()'
to check if the xdp_rxq is actually registered.
Thanks,
Michal
> + 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)
>
>
