netdev - Re: [PATCH v8 net-next 11/12] net: dsa: mv88e6xxx: add blackhole ATU entries

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Date:   Thu, 20 Oct 2022 16:11:01 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     "Hans J. Schultz" <netdev@...io-technology.com>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Kurt Kanzenbach <kurt@...utronix.de>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Shuah Khan <shuah@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Christian Marangi <ansuelsmth@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yuwei Wang <wangyuweihx@...il.com>,
        Petr Machata <petrm@...dia.com>,
        Ido Schimmel <idosch@...dia.com>,
        Florent Fourcot <florent.fourcot@...irst.fr>,
        Hans Schultz <schultz.hans@...il.com>,
        Joachim Wiberg <troglobit@...il.com>,
        Amit Cohen <amcohen@...dia.com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        bridge@...ts.linux-foundation.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v8 net-next 11/12] net: dsa: mv88e6xxx: add blackhole ATU
 entries

On Tue, Oct 18, 2022 at 06:56:18PM +0200, Hans J. Schultz wrote:
> Blackhole FDB entries can now be added, deleted or replaced in the
> driver ATU.

Why is this necessary, why is it useful?

> 
> Signed-off-by: Hans J. Schultz <netdev@...io-technology.com>
> ---
>  static int mv88e6xxx_port_fdb_add(struct dsa_switch *ds, int port,
>  				  const unsigned char *addr, u16 vid,
>  				  u16 fdb_flags, struct dsa_db db)
> @@ -2742,9 +2794,10 @@ static int mv88e6xxx_port_fdb_add(struct dsa_switch *ds, int port,
>  	struct mv88e6xxx_chip *chip = ds->priv;
>  	int err;
>  
> -	/* Ignore entries with flags set */
> -	if (fdb_flags)
> +	if (fdb_flags & DSA_FDB_FLAG_LOCKED)
>  		return 0;

I don't understand this. If no driver looks at DSA_FDB_FLAG_LOCKED
(not even mv88e6xxx, up until the end of the series), then why was it
propagated all the way in the first place?

> +	if (fdb_flags & DSA_FDB_FLAG_BLACKHOLE)
> +		return mv88e6xxx_blackhole_fdb_add(ds, addr, vid);
>  
>  	if (mv88e6xxx_port_is_locked(chip, port))
>  		mv88e6xxx_atu_locked_entry_find_purge(ds, port, addr, vid);
> @@ -2765,9 +2818,10 @@ static int mv88e6xxx_port_fdb_del(struct dsa_switch *ds, int port,
>  	bool locked_found = false;
>  	int err = 0;
>  
> -	/* Ignore entries with flags set */
> -	if (fdb_flags)
> +	if (fdb_flags & DSA_FDB_FLAG_LOCKED)
>  		return 0;
> +	if (fdb_flags & DSA_FDB_FLAG_BLACKHOLE)
> +		return mv88e6xxx_blackhole_fdb_del(ds, addr, vid);
>  
>  	if (mv88e6xxx_port_is_locked(chip, port))
>  		locked_found = mv88e6xxx_atu_locked_entry_find_purge(ds, port, addr, vid);
> -- 
> 2.34.1
>