netdev - Re: [PATCH net-next v4 4/8] bridge: mrp: Extend br_mrp

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Date:   Wed, 17 Feb 2021 17:02:56 +0100
From:   Horatiu Vultur <horatiu.vultur@...rochip.com>
To:     Vladimir Oltean <vladimir.oltean@....com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "jiri@...nulli.us" <jiri@...nulli.us>,
        "ivecera@...hat.com" <ivecera@...hat.com>,
        "nikolay@...dia.com" <nikolay@...dia.com>,
        "roopa@...dia.com" <roopa@...dia.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "vivien.didelot@...il.com" <vivien.didelot@...il.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "rasmus.villemoes@...vas.dk" <rasmus.villemoes@...vas.dk>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bridge@...ts.linux-foundation.org" 
        <bridge@...ts.linux-foundation.org>
Subject: Re: [PATCH net-next v4 4/8] bridge: mrp: Extend br_mrp_switchdev to
 detect better the errors

The 02/17/2021 10:56, Vladimir Oltean wrote:
> 
> On Tue, Feb 16, 2021 at 10:42:01PM +0100, Horatiu Vultur wrote:
> > This patch extends the br_mrp_switchdev functions to be able to have a
> > better understanding what cause the issue and if the SW needs to be used
> > as a backup.
> >
> > There are the following cases:
> > - when the code is compiled without CONFIG_NET_SWITCHDEV. In this case
> >   return success so the SW can continue with the protocol. Depending
> >   on the function, it returns 0 or BR_MRP_SW.
> > - when code is compiled with CONFIG_NET_SWITCHDEV and the driver doesn't
> >   implement any MRP callbacks. In this case the HW can't run MRP so it
> >   just returns -EOPNOTSUPP. So the SW will stop further to configure the
> >   node.
> > - when code is compiled with CONFIG_NET_SWITCHDEV and the driver fully
> >   supports any MRP functionality. In this case the SW doesn't need to do
> >   anything. The functions will return 0 or BR_MRP_HW.
> > - when code is compiled with CONFIG_NET_SWITCHDEV and the HW can't run
> >   completely the protocol but it can help the SW to run it. For
> >   example, the HW can't support completely MRM role(can't detect when it
> >   stops receiving MRP Test frames) but it can redirect these frames to
> >   CPU. In this case it is possible to have a SW fallback. The SW will
> >   try initially to call the driver with sw_backup set to false, meaning
> >   that the HW should implement completely the role. If the driver returns
> >   -EOPNOTSUPP, the SW will try again with sw_backup set to false,
> >   meaning that the SW will detect when it stops receiving the frames but
> >   it needs HW support to redirect the frames to CPU. In case the driver
> >   returns 0 then the SW will continue to configure the node accordingly.
> >
> > Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> > ---
> >  net/bridge/br_mrp_switchdev.c | 171 +++++++++++++++++++++-------------
> >  net/bridge/br_private_mrp.h   |  24 +++--
> >  2 files changed, 118 insertions(+), 77 deletions(-)
> >
> > diff --git a/net/bridge/br_mrp_switchdev.c b/net/bridge/br_mrp_switchdev.c
> > index 3c9a4abcf4ee..cb54b324fa8c 100644
> > --- a/net/bridge/br_mrp_switchdev.c
> > +++ b/net/bridge/br_mrp_switchdev.c
> > @@ -4,6 +4,30 @@
> >
> >  #include "br_private_mrp.h"
> >
> > +static enum br_mrp_hw_support
> > +br_mrp_switchdev_port_obj(struct net_bridge *br,
> > +                       const struct switchdev_obj *obj, bool add)
> > +{
> > +     int err;
> > +
> 
> Looks like you could have added this check here and simplified all the
> callers:
> 
>         if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
>                 return BR_MRP_SW;

Yes, good catch!

> 
> > +     if (add)
> > +             err = switchdev_port_obj_add(br->dev, obj, NULL);
> > +     else
> > +             err = switchdev_port_obj_del(br->dev, obj);
> > +
> > +     /* In case of success just return and notify the SW that doesn't need
> > +      * to do anything
> > +      */
> > +     if (!err)
> > +             return BR_MRP_HW;
> > +
> > +     if (err != -EOPNOTSUPP)
> > +             return BR_MRP_NONE;
> > +
> > +     /* Continue with SW backup */
> > +     return BR_MRP_SW;
> > +}
> > +

-- 
/Horatiu