netdev - Re: Does skb_metadata_differs really need to stop GRO aggregation?

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Message-ID: <0b0c6538-92a5-3041-bc48-d7286f1b873b@gmail.com>
Date: Wed, 29 Nov 2023 18:04:38 +0000
From: Edward Cree <ecree.xilinx@...il.com>
To: Toke Høiland-Jørgensen <toke@...hat.com>,
 Daniel Borkmann <daniel@...earbox.net>,
 Jesper Dangaard Brouer <hawk@...nel.org>
Cc: Yan Zhai <yan@...udflare.com>, Stanislav Fomichev <sdf@...gle.com>,
 Netdev <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
 Alexei Starovoitov <ast@...nel.org>, kernel-team
 <kernel-team@...udflare.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>,
 "David S. Miller" <davem@...emloft.net>,
 Jakub Sitnicki <jakub@...udflare.com>
Subject: Re: Does skb_metadata_differs really need to stop GRO aggregation?

On 28/11/2023 14:39, Toke Høiland-Jørgensen wrote:
> I'm not quite sure what should be the semantics of that, though. I.e.,
> if you are trying to aggregate two packets that have the flag set, which
> packet do you take the value from? What if only one packet has the flag
> set? Or should we instead have a "metadata_xdp_only" flag that just
> prevents the skb metadata field from being set entirely? Or would both
> be useful?

Sounds like what's actually needed is bpf progs inside the GRO engine
 to implement the metadata "protocol" prepare and coalesce callbacks?

-ed