netdev - Re: [PATCH bpf-next v2] net, xdp: allow metadata

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Message-ID: <ZUUE8lH+EbuRNI16@lzaremba-mobl.ger.corp.intel.com>
Date: Fri, 3 Nov 2023 15:34:26 +0100
From: Larysa Zaremba <larysa.zaremba@...el.com>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
CC: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, Alexei Starovoitov
	<ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, "David S. Miller"
	<davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, "Jesper Dangaard
 Brouer" <hawk@...nel.org>, Eric Dumazet <edumazet@...gle.com>, "Magnus
 Karlsson" <magnus.karlsson@...il.com>, Willem de Bruijn
	<willemdebruijn.kernel@...il.com>, Yunsheng Lin <linyunsheng@...wei.com>,
	Maciej Fijalkowski <maciej.fijalkowski@...el.com>, John Fastabend
	<john.fastabend@...il.com>
Subject: Re: [PATCH bpf-next v2] net, xdp: allow metadata > 32

On Fri, Nov 03, 2023 at 03:03:14PM +0100, Alexander Lobakin wrote:
> From: Larysa Zaremba <larysa.zaremba@...el.com>
> Date: Tue, 31 Oct 2023 18:57:37 +0100
> 
> It doesn't have "From: Alexa..." here, so that you'll be the author once
> this is applied. Is this intended? ^.^
>

No, I should probably resend.
 
> > 32 bytes may be not enough for some custom metadata. Relax the restriction,
> > allow metadata larger than 32 bytes and make __skb_metadata_differs() work
> > with bigger lengths.
> > 
> > Now size of metadata is only limited by the fact it is stored as u8
> > in skb_shared_info, so the upper limit is now is 255. Other important
> > conditions, such as having enough space for xdp_frame building, are already
> > checked in bpf_xdp_adjust_meta().
> 
> [...]
> 
> Thanks,
> Olek