Subject: Re: [PATCH net-next 2/2] tcp: add TCP_CC_INFO socket option

From: Daniel Borkmann <[email-masked]>
Date: Wed, 29 Apr 2015 10:17:23 +0200

On 04/29/2015 01:23 AM, Eric Dumazet wrote:
> Some Congestion Control modules can provide per flow information,
> but current way to get this information is to use netlink.
>
> Like TCP_INFO, let's add TCP_CC_INFO so that applications can
> issue a getsockopt() if they have a socket file descriptor,
> instead of playing complex netlink games.
>
> Sample usage would be :
>
>    union tcp_cc_info info;
>    socklen_t len = sizeof(info);
>
>    if (getsockopt(fd, SOL_TCP, TCP_CC_INFO, &info, &len) == -1)
>
> Signed-off-by: Eric Dumazet <[email-masked]>
> Cc: Yuchung Cheng <[email-masked]>
> Cc: Neal Cardwell <[email-masked]>

Presuming other cc algorithms would in future also export
internal information through this interface, would it make
sense to put tcp_cc_info into a container structure so we
don't miss out attr (vegas, dctcp, ...), like:

   struct tcp_cc_exp {
     u32               kind;
     union tcp_cc_info info;
   };

Otherwise looks good:

Acked-by: Daniel Borkmann <[email-masked]>