netdev - Re: [PATCH v8 net-next 02/12] net: bridge: add blackhole fdb entry flag

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Date:   Thu, 20 Oct 2022 21:34:05 +0200
From:   netdev@...io-technology.com
To:     Ido Schimmel <idosch@...dia.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>,
        Vladimir Oltean <olteanv@...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>,
        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 02/12] net: bridge: add blackhole fdb entry
 flag

On 2022-10-20 15:06, Ido Schimmel wrote:
> On Tue, Oct 18, 2022 at 06:56:09PM +0200, Hans J. Schultz wrote:
>> Add a 'blackhole' fdb flag, ensuring that no forwarding from any port
>> to a destination MAC that has a FDB entry with this flag on will 
>> occur.
>> The packets will thus be dropped.
>> 
>> When the blackhole fdb flag is set, the 'local' flag will also be 
>> enabled
>> as blackhole entries are not associated with any port.
> 
> It reads as if the kernel will enable the 'local' flag automatically,
> which is not true anymore. The bridge driver enforces that
> 'NUD_PERMANENT' is set if 'NTF_EXT_BLACKHOLE' is specified.
> 
>> 
>> Thus the command will be alike to:
>> bridge fdb add MAC dev br0 local blackhole
>> 
>> Signed-off-by: Hans J. Schultz <netdev@...io-technology.com>
> 
> Looks OK to me. See one comment below.
> 
> Reviewed-by: Ido Schimmel <idosch@...dia.com>
> 
> [...]
> 
>> @@ -1140,7 +1148,7 @@ static int __br_fdb_add(struct ndmsg *ndm, 
>> struct net_bridge *br,
>>  		err = br_fdb_external_learn_add(br, p, addr, vid, true);
>>  	} else {
>>  		spin_lock_bh(&br->hash_lock);
>> -		err = fdb_add_entry(br, p, addr, ndm, nlh_flags, vid, nfea_tb);
>> +		err = fdb_add_entry(br, p, addr, ndm, nlh_flags, vid, ext_flags, 
>> nfea_tb);
> 
> I believe the preference is to wrap to 80 columns when possible.

Ok, I only have knowledge of 100 columns as a limit.