netdev - Re: [PATCH net-next] ethtool: Block setting of symmetric RSS when non-symmetric rx-flow-hash is requested

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Message-ID: <20250317150741.GA688833@kernel.org>
Date: Mon, 17 Mar 2025 15:07:41 +0000
From: Simon Horman <horms@...nel.org>
To: Gal Pressman <gal@...dia.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Andrew Lunn <andrew+netdev@...n.ch>, netdev@...r.kernel.org,
	Andrew Lunn <andrew@...n.ch>, Tariq Toukan <tariqt@...dia.com>
Subject: Re: [PATCH net-next] ethtool: Block setting of symmetric RSS when
 non-symmetric rx-flow-hash is requested

On Mon, Mar 10, 2025 at 09:23:29AM +0200, Gal Pressman wrote:
> Symmetric RSS hash requires that:
> * No other fields besides IP src/dst and/or L4 src/dst

nit: I think it would read slightly better if the line above included a verb.
     Likewise for the code comment with the same text.

> * If src is set, dst must also be set
> 
> This restriction was only enforced when RXNFC was configured after
> symmetric hash was enabled. In the opposite order of operations (RXNFC
> then symmetric enablement) the check was not performed.
> 
> Perform the sanity check on set_rxfh as well, by iterating over all flow
> types hash fields and making sure they are all symmetric.
> 
> Introduce a function that returns whether a flow type is hashable (not
> spec only) and needs to be iterated over. To make sure that no one
> forgets to update the list of hashable flow types when adding new flow
> types, a static assert is added to draw the developer's attention.
> 
> Reviewed-by: Tariq Toukan <tariqt@...dia.com>
> Signed-off-by: Gal Pressman <gal@...dia.com>

The nit above not withstanding - take it or leave it - this looks good to me.

Reviewed-by: Simon Horman <horms@...nel.org>