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Date: Wed, 10 May 2023 13:00:08 +0800
From: Jason Wang <jasowang@...hat.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Feng Liu <feliu@...dia.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
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
>
> 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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