netdev - Re: [PATCH net-next] bpf: Add access to snd_cwnd and others in sock

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Date:   Tue, 5 Dec 2017 14:59:40 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Lawrence Brakmo <brakmo@...com>, netdev <netdev@...r.kernel.org>
Cc:     Alexei Starovoitov <ast@...com>, Kernel Team <Kernel-team@...com>,
        Blake Matheny <bmatheny@...com>,
        Vlad Dumitrescu <vladum@...gle.com>
Subject: Re: [PATCH net-next] bpf: Add access to snd_cwnd and others in
 sock_ops

On 12/05/2017 01:21 AM, Lawrence Brakmo wrote:
[...]
>     Just a question for clarification: do you need to have this in
>     the uapi struct as well? Meaning, do you have a specific use case
>     where you do this check out of the BPF program given the below
>     two snd_cwnd/srtt_us check this internally in the ctx rewrite?
>     
> Although is_fullsock is checked internally, the bpf program may want to
> verify if a return value of zero is due to a non fullsock state. The issue is
> that there are some ops that are called from both active and passive paths
> so it is not possible to know just by the op type.

Ok, fair point. Patch applied to bpf-next, thanks Lawrence!

>     Do you plan to reuse the ctx assignment also for bpf_setsockopt()
>     and bpf_getsockopt() internally?
> 
> If you mean, check is_fullsock instead of the call to sk_fullsock, then yes, it is
> a great idea. However, I would rather do it in another patch so we don’t delay
> this one (I have other things almost ready that depend on this patch).
That's fine by me.