netdev - RE: [PATCH net-next 1/9] net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC

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Date:   Wed, 14 Jun 2017 08:04:17 +0000
From:   "Mintz, Yuval" <Yuval.Mintz@...ium.com>
To:     Salil Mehta <salil.mehta@...wei.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "Zhuangyuzeng (Yisen)" <yisen.zhuang@...wei.com>,
        huangdaode <huangdaode@...ilicon.com>,
        "lipeng (Y)" <lipeng321@...wei.com>,
        "mehta.salil.lnk@...il.com" <mehta.salil.lnk@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>
Subject: RE: [PATCH net-next 1/9] net: hns3: Add support of HNS3 Ethernet
 Driver for hip08 SoC

> > > +static void hns3_nic_net_down(struct net_device *ndev) {
> > > +	struct hns3_nic_priv *priv = netdev_priv(ndev);
> > > +	struct hnae3_ae_ops *ops;
> > > +	int i;
> > > +
> > > +	netif_tx_stop_all_queues(ndev);
> > > +	netif_carrier_off(ndev);
> > > +	netif_tx_disable(ndev);
> > > +
> > > +	ops = priv->ae_handle->ae_algo->ops;
> > > +
> > > +	if (ops->stop)
> > > +		ops->stop(priv->ae_handle);
> > > +
> > > +	netif_tx_stop_all_queues(ndev);
> >
> > Looks a bit excessive. Why do you need all these
> > netif_tx_stop_all_queues()?
> If we are disabling the netdev. We need to stop scheduling the queues
> associated with that netdev for TX, so we need this code. Why do you think
> it is excessive?

Why do you need both netif_tx_disable() and netif_tx_stop_all_queues()?
And why would you need to re-do netif_tx_stop_all_queues() after
calling ops->stop()?

> > Isn't mqprio going to override your priority2tc mapping with the one
> > provided by user?
> I guess you are referring to below code in the mqprio_init() - right?
> 
> static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
> {
>   [...]
> 	/* Always use supplied priority mappings */
> 	for (i = 0; i < TC_BITMASK + 1; i++)
> 		netdev_set_prio_tc_map(dev, i, qopt->prio_tc_map[i]);
>   [...]
> }
> 
> In this case yes, you are right below code seems to be redundant:
> 
>  +	/* Assign UP2TC map for the VSI */
>  +	for (i = 0; i < HNAE3_MAX_TC; i++) {
>  +		netdev_set_prio_tc_map(ndev,
>  +				       kinfo->tc_info[i].up,
>  +				       kinfo->tc_info[i].tc);
> 
> Hope I am not missing anything here?
You're not; That's what I meant.