netdev - Re: [PATCH net] bonding: set default miimon value for non-arp modes if not set

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Date:   Sat, 21 Jul 2018 10:26:15 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     jarod@...hat.com
Cc:     linux-kernel@...r.kernel.org, j.vosburgh@...il.com,
        vfalico@...il.com, andy@...yhouse.net, maheshb@...gle.com,
        netdev@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH net] bonding: set default miimon value for non-arp
 modes if not set

From: Jarod Wilson <jarod@...hat.com>
Date: Wed, 18 Jul 2018 14:49:36 -0400

> For some time now, if you load the bonding driver and configure bond
> parameters via sysfs using minimal config options, such as specifying
> nothing but the mode, relying on defaults for everything else, modes
> that cannot use arp monitoring (802.3ad, balance-tlb, balance-alb) all
> wind up with both arp_interval=0 (as it should be) and miimon=0, which
> means the miimon monitor thread never actually runs. This is particularly
> problematic for 802.3ad.
 ...
> I believe this became a major issue as of commit 4d2c0cda0744, which for
> 802.3ad bonds, sets slave->link = BOND_LINK_DOWN, with a comment about
> relying on link monitoring via miimon to set it correctly, but since the
> miimon work queue never runs, the link just stays marked down.
> 
> If we simply tweak bond_option_mode_set() slightly, we can check for the
> non-arp modes having no miimon value set, and insert BOND_DEFAULT_MIIMON,
> which gets things back in full working order. This problem exists as far
> back as 4.14, and might be worth fixing in all stable trees since, though
> the work-around is to simply specify an miimon value yourself.
> 
> Reported-by: Bob Ball <ball@...ch.edu>
 ...
> Signed-off-by: Jarod Wilson <jarod@...hat.com>

Applied and queued up for -stable, thank you.