linux-kernel - Re: [PATCH net v2] virtio_net: Fix error unwinding of XDP initialization

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Message-ID: <a4676198-87d4-7472-425b-16fb4a39704f@nvidia.com>
Date:   Tue, 2 May 2023 15:42:13 -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>,
        William Tu <witu@...dia.com>, Parav Pandit <parav@...dia.com>
Subject: Re: [PATCH net v2] virtio_net: Fix error unwinding of XDP
 initialization



On 2023-05-02 p.m.2:32, Michael S. Tsirkin wrote:
> External email: Use caution opening links or attachments
> 
> 
> On Tue, May 02, 2023 at 01:41:34PM -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 a helper function of disable queue pairs, and use newly
>> introduced helper function in error unwinding and virtnet_close;
>>
>> Fixes: 754b8a21a96d ("virtio_net: setup xdp_rxq_info")
>> Signed-off-by: Feng Liu <feliu@...dia.com>
>> Reviewed-by: William Tu <witu@...dia.com>
>> Reviewed-by: Parav Pandit <parav@...dia.com>
>> Reviewed-by: Simon Horman <simon.horman@...igine.com>
>> Acked-by: Michael S. Tsirkin <mst@...hat.com>
>> ---
>>   drivers/net/virtio_net.c | 31 +++++++++++++++++++++----------
>>   1 file changed, 21 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 8d8038538fc4..5cd78e154d14 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 +1890,27 @@ 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;
>> +
>> +     /* error unwinding of xdp init */
> 
> btw we don't really need this comment - it's how all
> error handling is done anyways.
> if you need to roll v3, you can drop it.
> 
Will do, thx

>> +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);
>> +
>> +     return err;
>>   }
>>
>>   static int virtnet_poll_tx(struct napi_struct *napi, int budget)
>> @@ -2305,11 +2319,8 @@ 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)
>