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

On 11 September 2017 19:07:33 EEST, "Mahesh Bandewar (महेश बंडेवार)" [off-list ref] wrote:

On Sat, Sep 9, 2017 at 4:28 AM, Nikolay Aleksandrov
[off-list ref] wrote:

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On 07/09/17 01:47, Kosuke Tatsukawa wrote:

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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

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common usage).  In the latter case, tlb_dynamic_lb was set up

according

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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

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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

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other modes, because "mode" is usually set up only once during
initialization, and it's not worthwhile to change the static

variable

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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

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change that behavior, because the value of tlb_balance_lb can be

changed

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using the sysfs interface for balance-tlb, and I didn't like

changing

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the default value back and forth for balance-tlb.

As for balance-alb, /sys/class/net/*/bonding/tlb_balance_lb cannot

be

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written to.  However, I think balance-alb with tlb_dynamic_lb set to

0

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is not an intended usage, so there is little use making it writable

at

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this moment.

Fixes: 8b426dc54cf4 ("bonding: remove hardcoded value")
Reported-by: Reinis Rozitis <redacted>
Signed-off-by: Kosuke Tatsukawa <redacted>
Cc: stable@vger.kernel.org  # v4.12+
---
 drivers/net/bonding/bond_options.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

This fix is simpler and more suitable for -net, it fixes the case

where

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we switch to ALB mode with tlb_dynamic_lb = 0. After it is in I'll

fix the

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default tlb_dynamic_lb issue and restore the original behaviour.

Changing tlb_dyanamic_lb to initialize always is also safe for -net
and can go in before or after this change (no dependency on this
change as such)

I never said it was unsafe or dependent, it is simply my preference to wait. :-)
If you need it sooner feel free to post it.

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Acked-by: Nikolay Aleksandrov <redacted>

Acked-by: Mahesh Bandewar <redacted>

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