netdev - Re: [PATCH net-2.6] bonding: drop frames received with master's source MAC

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Message-ID: <20110301023525.GK11864@gospo.rdu.redhat.com>
Date:	Mon, 28 Feb 2011 21:35:25 -0500
From:	Andy Gospodarek <andy@...yhouse.net>
To:	Nicolas de Pesloüan 
	<nicolas.2p.debian@...il.com>
Cc:	Andy Gospodarek <andy@...yhouse.net>, netdev@...r.kernel.org,
	David Miller <davem@...emloft.net>,
	Herbert Xu <herbert@...dor.hengli.com.au>,
	Jay Vosburgh <fubar@...ibm.com>, Jiri Pirko <jpirko@...hat.com>
Subject: Re: [PATCH net-2.6] bonding: drop frames received with master's
	source MAC

On Mon, Feb 28, 2011 at 10:45:08PM +0100, Nicolas de Pesloüan wrote:
> Le 28/02/2011 17:32, Andy Gospodarek a écrit :
>> On Sat, Feb 26, 2011 at 12:08:03AM +0100, Nicolas de Pesloüan wrote:
>>> Le 25/02/2011 23:24, Andy Gospodarek a écrit :
>> [...]
>>>>
>>>> I confirmed your suspicion, this breaks ARP monitoring.  I would still
>>>> welcome other opinions though as I think it would be nice to fix this as
>>>> low as possible.
>>>
>>> Why do you want to fix it earlier that in ndisc_recv_ns drop? Your
>>> original idea of silently dropping the frame there seems perfect to me.
>>>
>>
>> Maybe it's just me, but I cannot understand why we want a bunch of extra
>> packets floating up into the stack when they may only create issues for
>> the recipients of these duplicate frames.
>>
>> Clearly my original patch needs to be refined so ARP monitoring still
>> works, but I would rather fix the issue there than in a higher layer.
>
> Jay explained that the current implementation should already trap those 
> frames, on inactive slaves, in modes where inactive slaves exist. I agree 
> with him.
>
> What mode are you seeing this problem in? If the current "should drop" 
> logic is leaking, then yes, we should fix it. But we currently don't see 
> where it is leaking.
>

Use round-robin.  To reproduce just take the interface down and bring it
back up.  You should see the messages right away.

I've been doing some more testing on a new patch and should have
something ready tomorrow.  My latest patch actually replaces the final
'return 0' with a call to a function that will return true if the sender
was the device that received it.  This will hopefully prevent some of
the failures with the first patch I posted.  I'll know a bit more
tomorrow if this approach seems reasonable.

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