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

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Message-ID: <20171203182646.26z3pu6keynirx4v@ast-mbp>
Date:   Sun, 3 Dec 2017 10:26:48 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Lawrence Brakmo <brakmo@...com>
Cc:     netdev <netdev@...r.kernel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>,
        Vlad Dumitrescu <vladum@...gle.com>
Subject: Re: [PATCH net-next] bpf: Add access to snd_cwnd and others in
 sock_ops

On Fri, Dec 01, 2017 at 10:15:04AM -0800, Lawrence Brakmo wrote:
> Adds read access to snd_cwnd and srtt_us fields of tcp_sock. Since these
> fields are only valid if the socket associated with the sock_ops program
> call is a full socket, the field is_fullsock is also added to the
> bpf_sock_ops struct. If the socket is not a full socket, reading these
> fields returns 0.
> 
> Note that in most cases it will not be necessary to check is_fullsock to
> know if there is a full socket. The context of the call, as specified by
> the 'op' field, can sometimes determine whether there is a full socket.
> 
> The struct bpf_sock_ops has the following fields added:
> 
>   __u32 is_fullsock;      /* Some TCP fields are only valid if
>                            * there is a full socket. If not, the
>                            * fields read as zero.
> 			   */
>   __u32 snd_cwnd;
>   __u32 srtt_us;          /* Averaged RTT << 3 in usecs */
> 
> There is a new macro, SOCK_OPS_GET_TCP32(NAME), to make it easier to add
> read access to more 32 bit tcp_sock fields.
> 
> Signed-off-by: Lawrence Brakmo <brakmo@...com>

lgtm
Acked-by: Alexei Starovoitov <ast@...nel.org>
will wait for Daniel to either ack it or apply it.