Date: Tue, 9 May 2023 10:08:14 -0400
From: Feng Liu <feliu@...dia.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
 Jason Wang <jasowang@...hat.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
 Simon Horman <simon.horman@...igine.com>, Bodong Wang <bodong@...dia.com>,
 Jiri Pirko <jiri@...dia.com>
Subject: Re: [PATCH net v4] virtio_net: Fix error unwinding of XDP
 initialization



On 2023-05-09 a.m.12:42, Michael S. Tsirkin wrote:
> External email: Use caution opening links or attachments
> 
> 
> 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@...dia.com>
>> Reviewed-by: Jiri Pirko <jiri@...dia.com>
>> ---
>>
>> 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)
> 

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