netdev - Re: [PATCH net-next] store complete hash type information in socket buffer...

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Message-ID: <1455744601.648.2.camel@edumazet-ThinkPad-T530>
Date:	Wed, 17 Feb 2016 22:30:01 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	paul.durrant@...rix.com, netdev@...r.kernel.org,
	j.vosburgh@...il.com, vfalico@...il.com, gospo@...ulusnetworks.com,
	tom@...bertland.com
Subject: Re: [PATCH net-next] store complete hash type information in socket
 buffer...

On mer., 2016-02-17 at 15:44 -0500, David Miller wrote:
> From: Paul Durrant <paul.durrant@...rix.com>
> Date: Mon, 15 Feb 2016 08:32:08 +0000
> 
> > ...rather than a boolean merely indicating a canonical L4 hash.
> > 
> > skb_set_hash() takes a hash type (from enum pkt_hash_types) as an
> > argument but information is lost since only a single bit in the skb
> > stores whether that hash type is PKT_HASH_TYPE_L4 or not. By using
> > two bits it's possible to store the complete hash type information.
> > 
> > Signed-off-by: Paul Durrant <paul.durrant@...rix.com>
> 
> Tom and/or Eric, please have a look at this.

I guess my question is simply 'why do we need this' ?

Consuming a bit in our precious sk_buff is not something we want for
some obscure feature.