linux-kernel - Re: [PATCH bpf-next 0/9] bpf: cpumap: enable GRO for XDP

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Message-ID: <20240904112957.3aaaa734@kernel.org>
Date: Wed, 4 Sep 2024 11:29:57 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
 <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Lorenzo
 Bianconi <lorenzo@...nel.org>, Daniel Xu <dxu@...uu.xyz>, John Fastabend
 <john.fastabend@...il.com>, Jesper Dangaard Brouer <hawk@...nel.org>,
 "Martin KaFai Lau" <martin.lau@...ux.dev>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni
 <pabeni@...hat.com>, <bpf@...r.kernel.org>, <netdev@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next 0/9] bpf: cpumap: enable GRO for XDP_PASS
 frames

On Wed, 4 Sep 2024 17:13:59 +0200 Alexander Lobakin wrote:
> >> I could say that gro_cells also "abuses" NAPI the same way, don't you
> >> think?  
> > 
> > "same way"? :] Does it allocate a fake netdev, use NAPI as a threading
> > abstraction or add extra fields to napi_struct ?   
> 
> Wait wait wait, you said "NAPI IRQ related logics doesn't fit here". I
> could say the same for gro_cells -- IRQ related NAPI logics doesn't fit
> there. gro_cells is an SW abstraction.

Yes, that 1/4th of my complaint does indeed apply :)

> A fake netdev is used by multiple drivers to use GRO, you know that
> (popular for wireless drivers). They also conflict with the queue config
> effort.

And it did cause us some issues when changing netdev_priv() already.