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

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Date:   Tue, 3 Aug 2021 16:19:03 +0000
From:   "Volodymyr Mytnyk [C]" <vmytnyk@...vell.com>
To:     Ido Schimmel <idosch@...sch.org>,
        Vadym Kochan <vadym.kochan@...ision.eu>
CC:     "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

Hi Ido,

Thanks for the review. Pls see the comments inline.

> On Mon, Aug 02, 2021 at 05:08:49PM +0300, Vadym Kochan wrote:
> > diff --git a/drivers/net/ethernet/marvell/prestera/prestera_flower.c b/drivers/net/ethernet/marvell/prestera/prestera_flower.c
> > index e571ba09ec08..76f30856ac98 100644
> > --- a/drivers/net/ethernet/marvell/prestera/prestera_flower.c
> > +++ b/drivers/net/ethernet/marvell/prestera/prestera_flower.c
> > @@ -5,6 +5,8 @@
> >  #include "prestera_acl.h"
> >  #include "prestera_flower.h"
> >
> > +#define PRESTERA_HW_TC_NUM   8
> > +
> >  static int prestera_flower_parse_actions(struct prestera_flow_block *block,
> >                                         struct prestera_acl_rule *rule,
> >                                         struct flow_action *flow_action,
> > @@ -30,6 +32,11 @@ static int prestera_flower_parse_actions(struct prestera_flow_block *block,
> >                case FLOW_ACTION_TRAP:
> >                        a_entry.id = PRESTERA_ACL_RULE_ACTION_TRAP;
> >                        break;
> > +             case FLOW_ACTION_POLICE:
> > +                     a_entry.id = PRESTERA_ACL_RULE_ACTION_POLICE;
> > +                     a_entry.police.rate = act->police.rate_bytes_ps;
> > +                     a_entry.police.burst = act->police.burst;
>
> If packet rate based policing is not supported, an error should be
> returned here with extack.

Agree, it makes sense.

>
> 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 ?

>
> > +                     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

>
> 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.