netdev - Re: Receive issues with bonding and vlans

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Date:	Thu, 06 May 2010 10:42:30 -0700
From:	Jay Vosburgh <fubar@...ibm.com>
To:	John Fastabend <john.r.fastabend@...el.com>
cc:	"Leech, Christopher" <christopher.leech@...el.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Andy Gospodarek <andy@...yhouse.net>,
	Patrick McHardy <kaber@...sh.net>,
	"bonding-devel@...ts.sourceforge.net" 
	<bonding-devel@...ts.sourceforge.net>
Subject: Re: Receive issues with bonding and vlans

John Fastabend <john.r.fastabend@...el.com> wrote:

>Jay Vosburgh wrote:
>> John Fastabend <john.r.fastabend@...el.com> wrote:
[...]
>>> #3 bond0 --> ethx
>>>   vlanx --> -|
>>>
>>> Here is the case where adding the IFF_SLAVE bit doesn't work as I
>>> hoped. We don't want to run skb_bond_should_drop here.
>>
>>         Yes, this is tricky because the VLAN device will copy the
>> dev->flags from the device it's placed atop, so the VLAN will inherit
>> the ethx's IFF_SLAVE flag.  This happens regardless of the setup order
>> (enslave ethX, then add VLAN, or vice versa).
>>
>
>This doesn't appear to be true, adding a VLAN on ethx then enslave ethx
>doesn't set the IFF_SLAVE flag on the VLAN.  Unless I am missing
>something.

	I tried this again, and yes, the vlan device inherits the flags
of the device at the time the vlan is added.

	I think I was confused because the vlan device doesn't lose
IFF_SLAVE if the underlying ethX is taken out of the bond.  I suspect
both of these behaviors are because netdev_set_master doesn't do a
notifier call (just an rtmsg_ifinfo) when it changes dev->flags outside
of dev_set_flags.

	I don't think the vlan device should pick up IFF_SLAVE, though,
when the vlan device itself is not a slave, so that part seems correct.

	-J

---
	-Jay Vosburgh, IBM Linux Technology Center, fubar@...ibm.com
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