Subject: Re: Question regarding failure utilizing bonding mode 5 (balance-tlb)

From: Veaceslav Falico <[email-masked]>
Date: Tue, 1 Oct 2013 14:58:44 +0200

On Tue, Oct 01, 2013 at 12:56:43PM +0000, Yuval Mintz wrote:
>> On Mon, Sep 30, 2013 at 11:30:40AM +0000, Yuval Mintz wrote:
>> >> > >Again, I think the permanent address is restored only when the bond
>> >> > >releases the slave, which I don't think happens when the slave is
>> unloaded.
>> >> >
>> >> > 	Given a bond0 with two slaves, eth0 and eth1, in tlb mode, eth0
>> >> > being the active,
>> >> >
>> >> > 	1) "ip link set dev eth0 down" which will fail over to eth1
>> >> > 		(swapping the contents of their dev_addr fields).
>> >> >
>> >> > 	2) "ip link set dev eth0 up" eth0 comes back up, reprograms its
>> >> > 		MAC to the wrong thing (what was in dev_addr).
>> >> >
>> >> > 	3) repeat steps 1 and 2 for eth1
>> >> >
>> >> > 	Is this correct?
>> >> >
>> >>
>> >> Yes, sorry for the earlier confusion.
>> >> I think in the case described `alb_swap_mac_addr()' will be called,
>> >> replacing eth0 and eth1's dev_addr, causing eth0 to have dev_addr
>> >> which defers from  the bond device's. Once eth0 reloads, it will use
>> >> the different MAC address for configuring FW/HW.
>> >
>> >Hi,
>> >
>> >Did you by any chance had the time to look at this issue?
>>
>> Hi Yuval,
>>
>> Sorry for getting into the discussion - but I've tried to understand the
>> problem and, possibly, find a fix.
>>
>> I'm not sure that I completely understand it, and I don't have currently
>> hardware on which to test it (though I might have it in the nearest
>> future), so, again, I really am not sure that I won't suggest something
>> completely stupid.
>>
>> Anyway, that being said, I hope that the following patch might fix the
>> problem. I've described the bug and the fix in the changelog, and the code
>> is pretty self-explanitory.
>>
>> And even if the patch fixes the issue - I'm not sure that it's the proper
>> and correct way to do it. But it's definitely worth a try... So, if it's
>> possible, could you please test this patch and see if it fixes it?
>>
>> Warning: I've just compile-tested it.
>>
>> So, FWIW...
>>
>
>Like you, I don't know if yours is the proper way of fixing the issue - but it did
>seem to fix it (the scenario that was described, at least)
>
>Tested-by: Yuval Mintz <[email-masked]>

Thank you!

I'll then try now to dig it a big futher, and if it happens that this fix is
really the one we need - I'll use your Tested-by, hope that you're ok with
that. Otherwise I'll send a new patch(set) with you in the CC.

Thanks again!

>
>Thanks,
>Yuval
>
>>  From 87e6c584b0ae0f0261610d60cf83778feb9c1edb Mon Sep 17
>> 00:00:00 2001
>> From: Veaceslav Falico <[email-masked]>
>> Date: Mon, 30 Sep 2013 23:14:23 +0200
>> Subject: [PATCH] bonding: ensure that TLB mode's active slave has correct
>> mac filter
>>
>> Currently, in TLB mode we change mac addresses only by memcpy-ing the to
>> net_device->dev_addr, without actually setting them via
>> dev_set_mac_address(). This permits us to receive all the traffic always on
>> one mac address.
>>
>> However, in case the interface flips, some drivers might enforce the
>> mac filtering for its FW/HW based on current ->dev_addr, and thus we won't
>> be able to receive traffic on that interface, in case it will be selected
>> as active in TLB mode.
>>
>> Fix it by setting the mac address forcefully on every new active slave that
>> we select in TLB mode.
>>
>> CC: Jay Vosburgh <[email-masked]>
>> CC: Andy Gospodarek <[email-masked]>
>> Signed-off-by: Veaceslav Falico <[email-masked]>
>> ---
>>   drivers/net/bonding/bond_alb.c | 17 +++++++++++++++++
>>   1 file changed, 17 insertions(+)
>>
>> diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
>> index e960418..576ccea 100644
>> --- a/drivers/net/bonding/bond_alb.c
>> +++ b/drivers/net/bonding/bond_alb.c
>> @@ -1699,6 +1699,23 @@ void bond_alb_handle_active_change(struct
>> bonding *bond, struct slave *new_slave
>>
>>   	ASSERT_RTNL();
>>
>> +	/* in TLB mode, the slave might flip down/up with the old dev_addr,
>> +	 * and thus filter bond->dev_addr's packets, so force bond's mac
>> +	 */
>> +	if (bond->params.mode == BOND_MODE_TLB) {
>> +		struct sockaddr sa;
>> +		u8 tmp_addr[ETH_ALEN];
>> +
>> +		memcpy(tmp_addr, new_slave->dev->dev_addr, ETH_ALEN);
>> +
>> +		memcpy(sa.sa_data, bond->dev->dev_addr, bond->dev-
>> >addr_len);
>> +		sa.sa_family = bond->dev->type;
>> +		/* we don't care if it can't change its mac, best effort */
>> +		dev_set_mac_address(new_slave->dev, &sa);
>> +
>> +		memcpy(new_slave->dev->dev_addr, tmp_addr, ETH_ALEN);
>> +	}
>> +
>>   	/* curr_active_slave must be set before calling alb_swap_mac_addr
>> */
>>   	if (swap_slave) {
>>   		/* swap mac address */
>> --
>> 1.8.4
>>
>>
>> >
>> >Thanks,
>> >Yuval
>> >
>> >--
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>
>