Subject: Re: [PATCH net] bonding: Avoid possible de-sync with arp_validate

From: Marcelo Ricardo Leitner <[email-masked]>
Date: Fri, 06 Sep 2013 15:13:06 -0300

Em 06-09-2013 14:56, Jay Vosburgh escreveu:
> Marcelo Ricardo Leitner <[email-masked]> wrote:
>
>> Hi Dave,
>>
>> Please queue this one for -stable trees too.
>>
>> Thanks.
>>
>> ---8<---
>>
>> As bond_store_arp_validation and bond_store_arp_interval doesn't
>> deal with each other, we can't chain both at bond_open, otherwise
>> we are open to this de-sync state, steps in sequence:
>> - bond is down
>> - arp_interval = 0
>> - arp_validate = 1 or 2
>> - bond is up
>> - arp_interval = 1
>>
>> This would lead to bond issuing ARP requests but never listening
>> to the replies, because the tap wasn't attached. After reaching
>> this state, while bond is up, setting arp_validate won't help
>> as it only acts if needed.
>
> 	You need to sign off you patch.

My bad, sorry

>> drivers/net/bonding/bond_main.c | 7 +++----
>> 1 file changed, 3 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 39e5b1c..805d098 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -3180,11 +3180,10 @@ static int bond_open(struct net_device *bond_dev)
>> 	if (bond->params.miimon)  /* link check interval, in milliseconds. */
>> 		queue_delayed_work(bond->wq, &bond->mii_work, 0);
>>
>> -	if (bond->params.arp_interval) {  /* arp interval, in milliseconds. */
>> +	if (bond->params.arp_interval)    /* arp interval, in milliseconds. */
>> 		queue_delayed_work(bond->wq, &bond->arp_work, 0);
>> -		if (bond->params.arp_validate)
>> -			bond->recv_probe = bond_arp_rcv;
>> -	}
>> +	if (bond->params.arp_validate)
>> +		bond->recv_probe = bond_arp_rcv;
>
> 	Won't this set the recv_probe when arp_interval is 0 (disabled)?
> That's going to make bonding look at a bunch of traffic it's not going
> to do anything with.

Yes.

> 	Why is this better than having bonding_store_arp_interval set
> recv_probe if arp_validate is set when it queues the arp_work?  And,
> presumably, clear the recv_probe if arp_interval is being cleared.
>
> 	-J

Yeah, no good. You're right.

Self-NACK here. Nikolay will submit a better patch later.

Thanks,
Marcelo

>> 	if (bond->params.mode == BOND_MODE_8023AD) {
>> 		queue_delayed_work(bond->wq, &bond->ad_work, 0);
>> --
>> 1.8.3.1
>>
>
> ---
> 	-Jay Vosburgh, IBM Linux Technology Center, [email-masked]
>
>
>