netdev - Re: [PATCH 1/3] net: bridge: Implement bridge flag local

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Date:   Mon, 14 Mar 2022 17:48:58 +0100
From:   Mattias Forsblad <mattias.forsblad@...il.com>
To:     Ido Schimmel <idosch@...sch.org>, mattias.forsblad+netdev@...il.com
Cc:     Nikolay Aleksandrov <razor@...ckwall.org>, netdev@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Roopa Prabhu <roopa@...dia.com>
Subject: Re: [PATCH 1/3] net: bridge: Implement bridge flag local_receive

On 2022-03-14 17:29, Ido Schimmel wrote:
> On Wed, Mar 02, 2022 at 07:27:25AM +0100, Mattias Forsblad wrote:
>> On 2022-03-01 23:36, Nikolay Aleksandrov wrote:
>>> On 1 March 2022 17:43:27 CET, Ido Schimmel <idosch@...sch.org> wrote:
>>>> On Tue, Mar 01, 2022 at 01:31:02PM +0100, Mattias Forsblad wrote:
>>>>> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
>>>>> index e0c13fcc50ed..5864b61157d3 100644
>>>>> --- a/net/bridge/br_input.c
>>>>> +++ b/net/bridge/br_input.c
>>>>> @@ -163,6 +163,9 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>>>>>  		break;
>>>>>  	}
>>>>>  
>>>>> +	if (local_rcv && !br_opt_get(br, BROPT_LOCAL_RECEIVE))
>>>>> +		local_rcv = false;
>>>>> +
>>>>
>>>> I don't think the description in the commit message is accurate:
>>>> "packets received on bridge ports will not be forwarded up". From the
>>>> code it seems that if packets hit a local FDB entry, then they will be
>>>> "forwarded up". Instead, it seems that packets will not be flooded
>>>> towards the bridge. In which case, why not maintain the same granularity
>>>> we have for the rest of the ports and split this into unicast /
>>>> multicast / broadcast?
>>>>
>>>
>>> Exactly my first thought - why not implement the same control for the bridge?
>>> Also try to minimize the fast-path hit, you can keep the needed changes 
>>> localized only to the cases where they are needed.
>>> I'll send a few more comments in a reply to the patch.
>>>
>>
>> Soo, if I understand you correctly, you want to have three different options?
>> local_receive_unicast
>> local_receive_multicast
>> local_receive_broadcast
> 
> My understanding of the feature is that you want to prevent flooding
> towards the bridge. In which case, it makes sense to keep the same
> granularity as for regular bridge ports and also name the options
> similarly. We already have several options that are applicable to both
> the bridge and bridge ports (e.g., 'mcast_router').
> 
> I suggest:
> 
> $ ip link help bridge
> Usage: ... bridge [ fdb_flush ]
>                   ...
>                   [ flood {on | off} ]
>                   [ mcast_flood {on | off} ]
>                   [ bcast_flood {on | off} ]
> 
> This is consistent with "bridge_slave".

Many thanks for your input. I'll have a go at a V2.

BR
Mattias Forsblad