Subject: Re: [net 06/10] net/mlx5: RSS, Block changing channels number when RXFH is configured

From: Jakub Kicinski <[email-masked]>
Date: Thu, 28 Mar 2024 22:31:49 -0700

On Tue, 26 Mar 2024 07:46:42 -0700 Saeed Mahameed wrote:
> Changing the channels number after configuring the receive
> flow hash indirection table may alter the RSS table size.
> The previous configuration may no longer be compatible with
> the new receive flow hash indirection table.
> 
> Block changing the channels number when RXFH is configured.

Do I understand correctly that this will block all set_channels
calls after indir table changes? This may be a little too risky
for a fix. Perhaps okay for net-next, but not a fix.

I'd think that setting indir table and then increasing the number 
of channels is a pretty legit maneuver, or even best practice
to allocate a queue outside of RSS.

Is it possible to make a narrower change, only rejecting the truly
problematic transitions?