linux-kernel - Re: [PATCH] net: bonding: Fix transmit load balancing in balance-alb mode if specified by sysfs

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Date:   Mon, 11 Sep 2017 14:26:00 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     tatsu@...jp.nec.com
Cc:     j.vosburgh@...il.com, vfalico@...il.com, andy@...yhouse.net,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org, r@...e.lv
Subject: Re: [PATCH] net: bonding: Fix transmit load balancing in
 balance-alb mode if specified by sysfs

From: Kosuke Tatsukawa <tatsu@...jp.nec.com>
Date: Wed, 6 Sep 2017 22:47:59 +0000

> Commit cbf5ecb30560 ("net: bonding: Fix transmit load balancing in
> balance-alb mode") tried to fix transmit dynamic load balancing in
> balance-alb mode, which wasn't working after commit 8b426dc54cf4
> ("bonding: remove hardcoded value").
> 
> It turned out that my previous patch only fixed the case when
> balance-alb was specified as bonding module parameter, and not when
> balance-alb mode was set using /sys/class/net/*/bonding/mode (the most
> common usage).  In the latter case, tlb_dynamic_lb was set up according
> to the default mode of the bonding interface, which happens to be
> balance-rr.
> 
> This additional patch addresses this issue by setting up tlb_dynamic_lb
> to 1 if "mode" is set to balance-alb through the sysfs interface.
> 
> I didn't add code to change tlb_balance_lb back to the default value for
> other modes, because "mode" is usually set up only once during
> initialization, and it's not worthwhile to change the static variable
> bonding_defaults in bond_main.c to a global variable just for this
> purpose.
> 
> Commit 8b426dc54cf4 also changes the value of tlb_dynamic_lb for
> balance-tlb mode if it is set up using the sysfs interface.  I didn't
> change that behavior, because the value of tlb_balance_lb can be changed
> using the sysfs interface for balance-tlb, and I didn't like changing
> the default value back and forth for balance-tlb.
> 
> As for balance-alb, /sys/class/net/*/bonding/tlb_balance_lb cannot be
> written to.  However, I think balance-alb with tlb_dynamic_lb set to 0
> is not an intended usage, so there is little use making it writable at
> this moment.
> 
> Fixes: 8b426dc54cf4 ("bonding: remove hardcoded value")
> Reported-by: Reinis Rozitis <r@...e.lv>
> Signed-off-by: Kosuke Tatsukawa <tatsu@...jp.nec.com>
> Cc: stable@...r.kernel.org  # v4.12+

Applied and queued up for -stable, thanks.