netdev - Re: [Bridge] [PATCH net-next v2 2/2] net: bridge: add per-port multicast flood flag

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Message-ID: <13f464c2-e8f4-b813-0023-634e899ca245@cumulusnetworks.com>
Date:   Wed, 31 Aug 2016 08:14:46 +0200
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Linus Lüssing <linus.luessing@...3.blue>
Cc:     netdev@...r.kernel.org, roopa@...ulusnetworks.com,
        bridge@...ts.linux-foundation.org, davem@...emloft.net
Subject: Re: [Bridge] [PATCH net-next v2 2/2] net: bridge: add per-port
 multicast flood flag

On 31/08/16 08:02, Nikolay Aleksandrov wrote:
> On 31/08/16 03:37, Linus Lüssing wrote:
>> On Tue, Aug 30, 2016 at 05:23:08PM +0200, Nikolay Aleksandrov via Bridge wrote:
>>> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
>>> index 1da3221845f1..ed0dd3340084 100644
>>> --- a/net/bridge/br_if.c
>>> +++ b/net/bridge/br_if.c
>>> @@ -362,7 +362,7 @@ static struct net_bridge_port *new_nbp(struct net_bridge *br,
>>>  	p->path_cost = port_cost(dev);
>>>  	p->priority = 0x8000 >> BR_PORT_BITS;
>>>  	p->port_no = index;
>>> -	p->flags = BR_LEARNING | BR_FLOOD;
>>> +	p->flags = BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD;
>>
>> I'm discontent with this new flag becoming the default.
>>
>> Could you elaborate a little more on your use-case, when/why do
>> you want/need this flag?
>>
> 
> The use case is the current default behaviour if we don't make this flag on by default
> then we'll change user-visible default behaviour. Right now we flood unregistered mcast
> traffic by default (if there's no querier and router port, which continues to function
> as before). Also we have the port flags equal to BR_AUTO_MASK by default.
> 
> Cheers,
>  Nik
> 

Actually there is one potential issue with br_auto_mask. I shouldn't change it because that
changes the requirement for a br_auto_port and it may change user-visible behaviour (e.g.
having to disable both unicast flood and multicast flood to get the same config for
auto ports).
I will drop that part of the patch later in v3, will wait for feedback until then.

Thanks