netdev - Re: [PATCH net] bonding: Force slave speed check after link state recovery for 802.3ad

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Date:   Mon, 22 Jul 2019 12:09:57 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     tlfalcon@...ux.ibm.com
Cc:     netdev@...r.kernel.org, bjking1@...ibm.com, pradeep@...ibm.com,
        jarod@...hat.com, j.vosburgh@...il.com, vfalico@...il.com,
        andy@...yhouse.net
Subject: Re: [PATCH net] bonding: Force slave speed check after link state
 recovery for 802.3ad

From: Thomas Falcon <tlfalcon@...ux.ibm.com>
Date: Tue, 16 Jul 2019 17:25:10 -0500

> The following scenario was encountered during testing of logical
> partition mobility on pseries partitions with bonded ibmvnic
> adapters in LACP mode.
> 
> 1. Driver receives a signal that the device has been
>    swapped, and it needs to reset to initialize the new
>    device.
> 
> 2. Driver reports loss of carrier and begins initialization.
> 
> 3. Bonding driver receives NETDEV_CHANGE notifier and checks
>    the slave's current speed and duplex settings. Because these
>    are unknown at the time, the bond sets its link state to
>    BOND_LINK_FAIL and handles the speed update, clearing
>    AD_PORT_LACP_ENABLE.
> 
> 4. Driver finishes recovery and reports that the carrier is on.
> 
> 5. Bond receives a new notification and checks the speed again.
>    The speeds are valid but miimon has not altered the link
>    state yet.  AD_PORT_LACP_ENABLE remains off.
> 
> Because the slave's link state is still BOND_LINK_FAIL,
> no further port checks are made when it recovers. Though
> the slave devices are operational and have valid speed
> and duplex settings, the bond will not send LACPDU's. The
> simplest fix I can see is to force another speed check
> in bond_miimon_commit. This way the bond will update
> AD_PORT_LACP_ENABLE if needed when transitioning from
> BOND_LINK_FAIL to BOND_LINK_UP.
> 
> CC: Jarod Wilson <jarod@...hat.com>
> CC: Jay Vosburgh <j.vosburgh@...il.com>
> CC: Veaceslav Falico <vfalico@...il.com>
> CC: Andy Gospodarek <andy@...yhouse.net>
> Signed-off-by: Thomas Falcon <tlfalcon@...ux.ibm.com>

Applied, thanks Thomas.