Subject: Re: [PATCH v4 net-next 02/12] bonding: permit using arp_validate with non-ab modes

From: Veaceslav Falico <[email-masked]>
Date: Tue, 18 Feb 2014 07:39:13 +0100

On Mon, Feb 17, 2014 at 04:22:21PM +0100, Nikolay Aleksandrov wrote:
>On 02/17/2014 03:41 PM, Veaceslav Falico wrote:
>> Currently it's disabled because it's sometimes hard, in typical configs, to
>> make it work - because of the nature how the loadbalance modes work - as
>> it's hard to deliver valid arp replies to correct slaves by the switch.
>>
>> However we still can use arp_validation in loadbalance with several other
>> configs, per example with arp_validate == 2 for backup with one broadcast
>> domain, without the switch(es) doing any balancing - this way we'd be (a
>> bit more) sure that the slave is up.
>>
>> So, enable it to let users decide which one works/suits them best. Also
>> remove the mode limitation from BOND_OPT_ARP_VALIDATE.
>>
>> CC: Jay Vosburgh <[email-masked]>
>> CC: Andy Gospodarek <[email-masked]>
>> Signed-off-by: Veaceslav Falico <[email-masked]>
>> ---
>>  Documentation/networking/bonding.txt | 6 +++---
>>  drivers/net/bonding/bond_main.c      | 4 ----
>>  drivers/net/bonding/bond_options.c   | 1 -
>>  3 files changed, 3 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt
>> index 5cdb229..96b4ad8 100644
>> --- a/Documentation/networking/bonding.txt
>> +++ b/Documentation/networking/bonding.txt
>> @@ -270,9 +270,9 @@ arp_ip_target
>>  arp_validate
>>
>>  	Specifies whether or not ARP probes and replies should be
>> -	validated in the active-backup mode.  This causes the ARP
>> -	monitor to examine the incoming ARP requests and replies, and
>> -	only consider a slave to be up if it is receiving the
>> +	validated in any mode that supports arp monitoring.  This causes
>> +	the ARP monitor to examine the incoming ARP requests and replies,
>> +	and only consider a slave to be up if it is receiving the
>>  	appropriate ARP traffic.
>>
>>  	Possible values are:
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 3c50bec..91c0248 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -4183,10 +4183,6 @@ static int bond_check_params(struct bond_params *params)
>>  	}
>>
>>  	if (arp_validate) {
>> -		if (bond_mode != BOND_MODE_ACTIVEBACKUP) {
>> -			pr_err("arp_validate only supported in active-backup mode\n");
>> -			return -EINVAL;
>> -		}
>>  		if (!arp_interval) {
>>  			pr_err("arp_validate requires arp_interval\n");
>>  			return -EINVAL;
>> diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
>> index f3eb44d..d566cab 100644
>> --- a/drivers/net/bonding/bond_options.c
>> +++ b/drivers/net/bonding/bond_options.c
>> @@ -151,7 +151,6 @@ static struct bond_option bond_opts[] = {
>>  		.id = BOND_OPT_ARP_VALIDATE,
>>  		.name = "arp_validate",
>>  		.desc = "validate src/dst of ARP probes",
>> -		.unsuppmodes = BOND_MODE_ALL_EX(BIT(BOND_MODE_ACTIVEBACKUP)),
>>  		.values = bond_arp_validate_tbl,
>>  		.set = bond_option_arp_validate_set
>>  	},
>>
>Sorry for not noticing before, but I just remembered the reason why all the
>checks are there when changing the recv_probe, especially from the options.
>The problem was that lacp mode also uses the recv_probe, so after this patch we
>can overwrite the recv_probe while it's running in lacp mode, because
>bond_option_arp_validate_set changes the recv_probe. We can actually only set it
>to NULL because arp_interval can't be set in those modes, but still we can break
>the mode and there'll be need for at least down/up cycle to fix it.
>I think rlb also uses the recv_probe so this applies to it as well.

Yep, missed that too, thanks a lot Nik. It should just be the same as for
BOND_OPT_ARP_INTERVAL:

  177                 .unsuppmodes = BIT(BOND_MODE_8023AD) | BIT(BOND_MODE_TLB) |
  178                                BIT(BOND_MODE_ALB),

which makes sense - as in those modes it's indeed more than useless.

I'll change it and send v5.

>Nik