netdev - Re: [PATCH net-next v2 4/4] net: marvell: prestera: Offload FLOW_ACTION

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Date:   Tue, 3 Aug 2021 19:46:44 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     "Volodymyr Mytnyk [C]" <vmytnyk@...vell.com>
Cc:     Vadym Kochan <vadym.kochan@...ision.eu>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vladimir Oltean <olteanv@...il.com>,
        Serhiy Boiko <serhiy.boiko@...ision.eu>,
        Volodymyr Mytnyk <volodymyr.mytnyk@...ision.eu>,
        Taras Chornyi <taras.chornyi@...ision.eu>,
        "Taras Chornyi [C]" <tchornyi@...vell.com>,
        Mickey Rachamim <mickeyr@...vell.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Vadym Kochan [C]" <vkochan@...vell.com>
Subject: Re: [PATCH net-next v2 4/4] net: marvell: prestera: Offload
 FLOW_ACTION_POLICE

On Tue, Aug 03, 2021 at 04:19:03PM +0000, Volodymyr Mytnyk [C] wrote:
> > On Mon, Aug 02, 2021 at 05:08:49PM +0300, Vadym Kochan wrote:
> > It seems the implementation assumes that each rule has a different
> > policer, so an error should be returned in case the same policer is
> > shared between different rules.
> 
> Each rule has a different policer assigned by HW. Do you mean the police.index should be checked here ?

Yes. Checked to make sure each rule uses a different policer.

> 
> >
> > > +                     break;
> > >                default:
> > >                        NL_SET_ERR_MSG_MOD(extack, "Unsupported action");
> > >                        pr_err("Unsupported action\n");
> > > @@ -110,6 +117,17 @@ static int prestera_flower_parse(struct prestera_flow_block *block,
> > >                return -EOPNOTSUPP;
> > >        }
> > >
> > > +     if (f->classid) {
> > > +             int hw_tc = __tc_classid_to_hwtc(PRESTERA_HW_TC_NUM, f->classid);
> > > +
> > > +             if (hw_tc < 0) {
> > > +                     NL_SET_ERR_MSG_MOD(f->common.extack, "Unsupported HW TC");
> > > +                     return hw_tc;
> > > +             }
> > > +
> > > +             prestera_acl_rule_hw_tc_set(rule, hw_tc);
> > > +     }
> >
> > Not sure what this is. Can you show a command line example of how this
> > is used?
> 
> This is HW traffic class used for packets that are trapped to CPU port. The usage is as the following:
> 
> tc qdisc add dev DEV clsact
> tc filter add dev DEV ingress flower skip_sw dst_mac 00:AA:AA:AA:AA:00 hw_tc 1 action trap

You are not using any police action in this example and the changelogs
do not say anything about trap / CPU port so I fail to understand how
this hunk is related to the submission.

> 
> >
> > What about visibility regarding number of packets that were dropped by
> > the policer?
> 
> This is not support at this moment by the driver, so it is always zero now.

You plan to support it? I imagine the hardware policer is able to report
the number of packets it dropped.