linux-kernel - Re: [PATCH V3 net-next 1/4] net: bridge: add fdb flag to extent locked port feature

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Message-ID: <86sfonjroi.fsf@gmail.com>
Date:   Thu, 02 Jun 2022 12:17:01 +0200
From:   Hans Schultz <schultz.hans@...il.com>
To:     Nikolay Aleksandrov <razor@...ckwall.org>,
        Hans Schultz <schultz.hans@...il.com>,
        Ido Schimmel <idosch@...dia.com>
Cc:     Ido Schimmel <idosch@...sch.org>, davem@...emloft.net,
        kuba@...nel.org, netdev@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>, Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>, Shuah Khan <shuah@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        linux-kernel@...r.kernel.org, bridge@...ts.linux-foundation.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH V3 net-next 1/4] net: bridge: add fdb flag to extent
 locked port feature

On tor, jun 02, 2022 at 12:33, Nikolay Aleksandrov <razor@...ckwall.org> wrote:
> On 02/06/2022 12:17, Hans Schultz wrote:
>> On tis, maj 31, 2022 at 17:23, Ido Schimmel <idosch@...dia.com> wrote:
>>> On Tue, May 31, 2022 at 11:34:21AM +0200, Hans Schultz wrote:

>> Another issue is that
>> bridge fdb add MAC dev DEV master static
>> seems to add the entry with the SELF flag set, which I don't think is
>> what we would want it to do or?
>
> I don't see such thing (hacked iproute2 to print the flags before cmd):
> $ bridge fdb add 00:11:22:33:44:55 dev vnet110 master static
> flags 0x4
>
> 0x4 = NTF_MASTER only
>

I also get 0x4 from iproute2, but I still get SELF entries when I look
with:
bridge fdb show dev DEV

>> Also the replace command is not really supported properly as it is. I
>> have made a fix for that which looks something like this:
>> 
>> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
>> index 6cbb27e3b976..f43aa204f375 100644
>> --- a/net/bridge/br_fdb.c
>> +++ b/net/bridge/br_fdb.c
>> @@ -917,6 +917,9 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
>>                 if (flags & NLM_F_EXCL)
>>                         return -EEXIST;
>>  
>> +               if (flags & NLM_F_REPLACE)
>> +                       modified = true;
>> +
>>                 if (READ_ONCE(fdb->dst) != source) {
>>                         WRITE_ONCE(fdb->dst, source);
>>                         modified = true;
>> 
>> The argument for always sending notifications to the driver in the case
>> of replace is that a replace command will refresh the entries timeout if
>> the entry is the same. Any thoughts on this?
>
> I don't think so. It always updates its "used" timer, not its "updated" timer which is the one
> for expire. A replace that doesn't actually change anything on the entry shouldn't generate
> a notification.

Okay, so then there is missing checks on flags as the issue arose from
replacing locked entries with dynamic entries. I will do another fix
based on flags as modified needs to be true for the driver to get notified.