Re: [PATCH v2 net-next] net: core: use listified Rx for GRO_NORMAL in napi_gro_receive()

[Alexander Lobakin]

Edward Cree wrote 25.11.2019 16:21:
> On 25/11/2019 12:02, Alexander Lobakin wrote:
> > I'm not very familiar with iwlwifi, but as a work around manual
> > napi_gro_flush() you can also manually flush napi->rx_list to
> > prevent packets from stalling:
> >
> > diff -Naur a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c 
> > b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
> > --- a/drivers/net/wireless/intel/iwlwifi/pcie/rx.cÂÂÂ 2019-11-25 
> > 14:55:03.610355230 +0300
> > +++ b/drivers/net/wireless/intel/iwlwifi/pcie/rx.cÂÂÂ 2019-11-25 
> > 14:57:29.399556868 +0300
> > @@ -1526,8 +1526,16 @@
> > ÂÂÂÂ if (unlikely(emergency && count))
> > ÂÂÂÂÂÂÂÂ iwl_pcie_rxq_alloc_rbs(trans, GFP_ATOMIC, rxq);
> >
> > -ÂÂÂ if (rxq->napi.poll)
> > +ÂÂÂ if (rxq->napi.poll) {
> > +ÂÂÂÂÂÂÂ if (rxq->napi.rx_count) {
> > +ÂÂÂÂÂÂÂÂÂÂÂ netif_receive_skb_list(&rxq->napi.rx_list);
> > +
> > +ÂÂÂÂÂÂÂÂÂÂÂ INIT_LIST_HEAD(&rxq->napi.rx_list);
> > +ÂÂÂÂÂÂÂÂÂÂÂ rxq->napi.rx_count = 0;
> > +ÂÂÂÂÂÂÂ }
> > +
> > ÂÂÂÂÂÂÂÂ napi_gro_flush(&rxq->napi, false);
> > +ÂÂÂ }
> >
> > ÂÂÂÂ iwl_pcie_rxq_restock(trans, rxq);
> > Â}
> ... or we could export gro_normal_list(), instead of open-coding it
> Âin the driver?

I thought about this too, but don't like it. This patch is proposed as
a *very* temporary solution until iwlwifi will get more straightforward
logic. I wish we could make napi_gro_flush() static in the future and
keep gro_normal_list() private to:

- prevent them from using in any new drivers;
- give more opportunity to CC to optimize the core code.

> -Ed

Regards,
á á á á á á