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Message-ID: <17f9d4ef-9493-3fcd-65ff-beb92f99f854@nvidia.com>
Date: Wed, 10 May 2023 07:54:49 -0400
From: Feng Liu <feliu@...dia.com>
To: Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: "Michael S . Tsirkin" <mst@...hat.com>,
Simon Horman <simon.horman@...igine.com>,
Bodong Wang <bodong@...dia.com>, William Tu <witu@...dia.com>,
Parav Pandit <parav@...dia.com>,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH net v3] virtio_net: Fix error unwinding of XDP
initialization
On 2023-05-10 a.m.1:00, Jason Wang wrote:
> External email: Use caution opening links or attachments
>
>
> 在 2023/5/9 09:43, Xuan Zhuo 写道:
>> On Mon, 8 May 2023 11:00:10 -0400, Feng Liu <feliu@...dia.com> wrote:
>>>
>>> On 2023-05-07 p.m.9:45, Xuan Zhuo wrote:
>>>> External email: Use caution opening links or attachments
>>>>
>>>>
>>>> On Sat, 6 May 2023 08:08:02 -0400, Feng Liu <feliu@...dia.com> wrote:
>>>>>
>>>>> 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@...dia.com> 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@...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>
>>>>>>> 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
>>>> This is not the point, the key is whether we should handle with:
>>>>
>>>> disable_delayed_refill(vi);
>>>> cancel_delayed_work_sync(&vi->refill);
>>>>
>>>> Thanks.
>>>>
>>>>
>>> OK, get the point. Thanks for your careful review. And I check the code
>>> again.
>>>
>>> There are two points that I need to explain:
>>>
>>> 1. All refill delay work calls(vi->refill, vi->refill_enabled) are based
>>> on that the virtio interface is successfully opened, such as
>>> virtnet_receive, virtnet_rx_resize, _virtnet_set_queues, etc. If there
>>> is an error in the xdp reg here, it will not trigger these subsequent
>>> functions. There is no need to call disable_delayed_refill() and
>>> cancel_delayed_work_sync().
>> Maybe something is wrong. I think these lines may call delay work.
>>
>> static int virtnet_open(struct net_device *dev)
>> {
>> struct virtnet_info *vi = netdev_priv(dev);
>> int i, err;
>>
>> enable_delayed_refill(vi);
>>
>> for (i = 0; i < vi->max_queue_pairs; i++) {
>> if (i < vi->curr_queue_pairs)
>> /* Make sure we have some buffers: if oom use
>> wq. */
>> --> 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);
>> 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);
>> }
>>
>> return 0;
>> }
>>
>>
>> And I think, if we virtnet_open() return error, then the status of
>> virtnet
>> should like the status after virtnet_close().
>>
>> Or someone has other opinion.
>
>
> I agree, we need to disable and sync with the refill work.
>
> Thanks
>
>
OK，got it.
Thanks Jason & Xuan
>>
>> Thanks.
>>
>>> The logic here is different from that of
>>> virtnet_close. virtnet_close is based on the success of virtnet_open and
>>> the tx and rx has been carried out normally. For error unwinding, only
>>> disable qp is needed. Also encapuslated a helper function of disable qp,
>>> which is used ing error unwinding and virtnet close
>>> 2. The current error qp, which has not enabled NAPI, can only call xdp
>>> unreg, and cannot call the interface of disable NAPI, otherwise the
>>> kernel will be stuck. So for i-- the reason for calling disable qp on
>>> the previous queue
>>>
>>> Thanks
>>>
>>>>>>> +
>>>>>>> + 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)
>>>>>>>
>
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