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From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To: Ignat Korchagin <ignat@cloudflare.com>, "David S . Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Jakub Kicinski
 <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: kernel-team@cloudflare.com, Ignat Korchagin <ignat@cloudflare.com>
Subject: Re: [PATCH] net: veth: do not manipulate GRO when using XDP
In-Reply-To: <20240311124015.38106-1-ignat@cloudflare.com>
References: <20240311124015.38106-1-ignat@cloudflare.com>
Date: Tue, 12 Mar 2024 10:10:40 +0100
Message-ID: <87zfv3q0hb.fsf@toke.dk>
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Ignat Korchagin <ignat@cloudflare.com> writes:

> Commit d3256efd8e8b ("veth: allow enabling NAPI even without XDP") tried =
to fix
> the fact that GRO was not possible without XDP, because veth did not use =
NAPI
> without XDP. However, it also introduced the behaviour that GRO is always
> enabled, when XDP is enabled.
>
> While it might be desired for most cases, it is confusing for the user at=
 best
> as the GRO flag sudddenly changes, when an XDP program is attached. It al=
so
> introduces some complexities in state management as was partially address=
ed in
> commit fe9f801355f0 ("net: veth: clear GRO when clearing XDP even when do=
wn").
>
> But the biggest problem is that it is not possible to disable GRO at all,=
 when
> an XDP program is attached, which might be needed for some use cases.
>
> Fix this by not touching the GRO flag on XDP enable/disable as the code a=
lready
> supports switching to NAPI if either GRO or XDP is requested.

Sounds reasonable

Reviewed-by: Toke H=C3=B8iland-J=C3=B8rgensen <toke@redhat.com>