netdev - Re: [PATCH net-next 10/11] ethtool: rss: support setting flow hashing fields

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Message-ID: <20250715075038.6d37812a@kernel.org>
Date: Tue, 15 Jul 2025 07:50:38 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Gal Pressman <gal@...dia.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
 pabeni@...hat.com, andrew+netdev@...n.ch, horms@...nel.org,
 donald.hunter@...il.com, shuah@...nel.org, kory.maincent@...tlin.com,
 maxime.chevallier@...tlin.com, sdf@...ichev.me, ecree.xilinx@...il.com
Subject: Re: [PATCH net-next 10/11] ethtool: rss: support setting flow
 hashing fields

On Tue, 15 Jul 2025 13:27:51 +0300 Gal Pressman wrote:
> > IOCTL has two separate calls for this so there's no way to even try
> > to change both at once. I'll add "unlike IOCTL which has separate
> > calls" ?  
> 
> So it's different because you can use netlink directly to change both,
> but from userspace ethtool perspective there's no difference, right?
> It's still two commands.

Yup! The existing CLI will likely stay as is.

> Makes sense, thanks for the explanation.
> 
> >> Why not use mod?  
> > 
> > Because it's a difference driver-facing op.  
> 
> Why do we need to differentiate where the mod originated? We have a
> single return value.

Right, but if we only modified the indirection table there's no need 
to call the driver to update the hashing fields and vice versa.
To be clear this is just "an optimization", doesn't affect correctness
in any way.