[next] bonding: speed/duplex update at NETDEV_UP event

From: Mahesh Bandewar <maheshb@google.com>

Some NIC drivers don't have correct speed/duplex settings at the
time they send NETDEV_UP notification and that messes up the
bonding state. Especially 802.3ad mode which is very sensitive
to these settings. In the current implementation we invoke
bond_update_speed_duplex() when we receive NETDEV_UP, however,
ignore the return value. If the values we get are invalid
(UNKNOWN), then slave gets removed from the aggregator with
speed and duplex set to UNKNOWN while link is still marked as UP.

This patch fixes this scenario. Also 802.3ad mode is sensitive to
these conditions while other modes are not, so making sure that it
doesn't change the behavior for other modes.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
---
 drivers/net/bonding/bond_main.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

On Wed, 27 Sep 2017 18:03:49 -0700
Mahesh Bandewar <mahesh@bandewar.net> wrote:

> From: Mahesh Bandewar <maheshb@google.com>
> 
> Some NIC drivers don't have correct speed/duplex settings at the
> time they send NETDEV_UP notification and that messes up the
> bonding state. Especially 802.3ad mode which is very sensitive
> to these settings. In the current implementation we invoke
> bond_update_speed_duplex() when we receive NETDEV_UP, however,
> ignore the return value. If the values we get are invalid
> (UNKNOWN), then slave gets removed from the aggregator with
> speed and duplex set to UNKNOWN while link is still marked as UP.
> 
> This patch fixes this scenario. Also 802.3ad mode is sensitive to
> these conditions while other modes are not, so making sure that it
> doesn't change the behavior for other modes.
> 
> Signed-off-by: Mahesh Bandewar <maheshb@google.com>
> ---
>  drivers/net/bonding/bond_main.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index b7313c1d9dcd..177be373966b 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -3076,7 +3076,16 @@ static int bond_slave_netdev_event(unsigned long event,
>  		break;
>  	case NETDEV_UP:
>  	case NETDEV_CHANGE:
> -		bond_update_speed_duplex(slave);
> +		/* For 802.3ad mode only:
> +		 * Getting invalid Speed/Duplex values here will put slave
> +		 * in weird state. So mark it as link-down for the time
> +		 * being and let link-monitoring (miimon) set it right when
> +		 * correct speeds/duplex are available.
> +		 */
> +		if (bond_update_speed_duplex(slave) &&
> +		    BOND_MODE(bond) == BOND_MODE_8023AD)
> +			slave->link = BOND_LINK_DOWN;
> +
>  		if (BOND_MODE(bond) == BOND_MODE_8023AD)
>  			bond_3ad_adapter_speed_duplex_changed(slave);
>  		/* Fallthrough */

Then fix the drivers. Trying to workaround it here isn't helping.

The problem is that miimon is not required.  Bonding can be purely
event driven.

On Fri, Sep 29, 2017 at 1:08 PM, Stephen Hemminger
<stephen@networkplumber.org> wrote:
> On Wed, 27 Sep 2017 18:03:49 -0700
> Mahesh Bandewar <mahesh@bandewar.net> wrote:
>
>> From: Mahesh Bandewar <maheshb@google.com>
>>
>> Some NIC drivers don't have correct speed/duplex settings at the
>> time they send NETDEV_UP notification and that messes up the
>> bonding state. Especially 802.3ad mode which is very sensitive
>> to these settings. In the current implementation we invoke
>> bond_update_speed_duplex() when we receive NETDEV_UP, however,
>> ignore the return value. If the values we get are invalid
>> (UNKNOWN), then slave gets removed from the aggregator with
>> speed and duplex set to UNKNOWN while link is still marked as UP.
>>
>> This patch fixes this scenario. Also 802.3ad mode is sensitive to
>> these conditions while other modes are not, so making sure that it
>> doesn't change the behavior for other modes.
>>
>> Signed-off-by: Mahesh Bandewar <maheshb@google.com>
>> ---
>>  drivers/net/bonding/bond_main.c | 11 ++++++++++-
>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index b7313c1d9dcd..177be373966b 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -3076,7 +3076,16 @@ static int bond_slave_netdev_event(unsigned long event,
>>               break;
>>       case NETDEV_UP:
>>       case NETDEV_CHANGE:
>> -             bond_update_speed_duplex(slave);
>> +             /* For 802.3ad mode only:
>> +              * Getting invalid Speed/Duplex values here will put slave
>> +              * in weird state. So mark it as link-down for the time
>> +              * being and let link-monitoring (miimon) set it right when
>> +              * correct speeds/duplex are available.
>> +              */
>> +             if (bond_update_speed_duplex(slave) &&
>> +                 BOND_MODE(bond) == BOND_MODE_8023AD)
>> +                     slave->link = BOND_LINK_DOWN;
>> +
>>               if (BOND_MODE(bond) == BOND_MODE_8023AD)
>>                       bond_3ad_adapter_speed_duplex_changed(slave);
>>               /* Fallthrough */
>
> Then fix the drivers. Trying to workaround it here isn't helping.
>
This is not a workaround. It avoids bonding state being weird.

> The problem is that miimon is not required.  Bonding can be purely
> event driven.
>
really? Here is a code-snippet from bonding itself -

        /* reset values for 802.3ad/TLB/ALB */
        if (!bond_mode_uses_arp(bond_mode)) {
                if (!miimon) {
                        pr_warn("Warning: miimon must be specified,
otherwise bonding will not detect link failure, speed and duplex which
are essential for 802.3ad operation\n");
                        pr_warn("Forcing miimon to 100msec\n");
                        miimon = BOND_DEFAULT_MIIMON;
                }
        }

From: Mahesh Bandewar <mahesh@bandewar.net>
Date: Wed, 27 Sep 2017 18:03:49 -0700

> From: Mahesh Bandewar <maheshb@google.com>
> 
> Some NIC drivers don't have correct speed/duplex settings at the
> time they send NETDEV_UP notification and that messes up the
> bonding state. Especially 802.3ad mode which is very sensitive
> to these settings. In the current implementation we invoke
> bond_update_speed_duplex() when we receive NETDEV_UP, however,
> ignore the return value. If the values we get are invalid
> (UNKNOWN), then slave gets removed from the aggregator with
> speed and duplex set to UNKNOWN while link is still marked as UP.
> 
> This patch fixes this scenario. Also 802.3ad mode is sensitive to
> these conditions while other modes are not, so making sure that it
> doesn't change the behavior for other modes.
> 
> Signed-off-by: Mahesh Bandewar <maheshb@google.com>

Applied, thanks.