Re: [PATCH net-next v4 4/4] virtio-net: support rx netdim

[Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>]

在 2023/11/22 下午5:29, Yinjun Zhang 写道:
> On Mon, 20 Nov 2023 20:37:34 +0800, Heng Qi wrote:
> <...>
> > @@ -2179,6 +2220,7 @@ static void virtnet_disable_queue_pair(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);
> > +	cancel_work_sync(&vi->rq[qp_index].dim.work);
> I'm not sure, but please check if here may cause deadlock:
>   rtnl_lock held ->
>   .ndo_stop ->
>   virtnet_disable_queue_pair() ->
>   cancel_work_sync() ->
>   virtnet_rx_dim_work() ->
>   rtnl_lock()

Good catch!

I tried using cancel_work() which solves the problem. Additionally I 
tested the
scenario of ctrl cmd/.remove/.ndo_stop()/dim_work when there is a lot of 
concurrency,
and this can work very well.

Thanks!

> >   }
> >   
> >   static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
> <...>