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Subject: Re: [PATCH bpf] bpf: only test gso type on gso packets
To:     Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        netdev@vger.kernel.org
Cc:     ast@kernel.org, Willem de Bruijn <willemb@google.com>
References: <20190306193515.125072-1-willemdebruijn.kernel@gmail.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <d2993173-b434-d87e-36fa-5a93b797698a@iogearbox.net>
Date:   Thu, 7 Mar 2019 11:06:48 +0100
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On 03/06/2019 08:35 PM, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@google.com>
> 
> BPF can adjust gso only for tcp bytestreams. Fail on other gso types.
> 
> But only on gso packets. It does not touch this field if !gso_size.
> 
> Fixes: b90efd225874 ("bpf: only adjust gso_size on bytestream protocols")
> Signed-off-by: Willem de Bruijn <willemb@google.com>

Good catch, applied, thanks!

> Stupid bug on my part. Found only when adding tests for the feature.
> Will try to upstream those once bpf-next opens.
> 
> On a related note, also working on a flag BPF_F_ADJ_ROOM_FIXED_GSO
> that will allow reenabling this field for UDP (and possibly avoiding
> the expensive skb_cow for the TCP common case).

Nice, looking forward!