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Feng Liu

2023-May-08 15:00 UTC

[PATCH net v3] virtio_net: Fix error unwinding of XDP initialization

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 at nvidia.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 at
nvidia.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 at nvidia.com>
>>>> Reviewed-by: William Tu <witu at nvidia.com>
>>>> Reviewed-by: Parav Pandit <parav at nvidia.com>
>>>> Reviewed-by: Simon Horman <simon.horman at corigine.com>
>>>> Acked-by: Michael S. Tsirkin <mst at redhat.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(). 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)
>>>>

Xuan Zhuo

2023-May-09 01:43 UTC

head link

[PATCH net v3] virtio_net: Fix error unwinding of XDP initialization

On Mon, 8 May 2023 11:00:10 -0400, Feng Liu <feliu at nvidia.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 at
nvidia.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 at
nvidia.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 at nvidia.com>
> >>>> Reviewed-by: William Tu <witu at nvidia.com>
> >>>> Reviewed-by: Parav Pandit <parav at nvidia.com>
> >>>> Reviewed-by: Simon Horman <simon.horman at
corigine.com>
> >>>> Acked-by: Michael S. Tsirkin <mst at redhat.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.

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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