netdev - Re: iproute2 ss outputs duplicate tcp sockets info on kernel 3.10.105

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Date:   Wed, 10 May 2017 12:37:23 +0200
From:   Phil Sutter <phil@....cc>
To:     Li Er <phoooyb@...il.com>
Cc:     netdev@...r.kernel.org, Cyrill Gorcunov <gorcunov@...il.com>
Subject: Re: iproute2 ss outputs duplicate tcp sockets info on kernel 3.10.105

Hi,

Cc'ing Cyrill who wrote the code in question. Maybe he has an idea
what's going wrong here.

Cheers, Phil

On Mon, May 08, 2017 at 06:56:04PM -0700, Li Er wrote:
> i'm using v4.11.0 release of iproute2 and kernel 3.10.105, simply
> running
> 
>         $ ss
>         Netid  State      Recv-Q Send-Q Local Address:Port                 Peer Address:Port
>         tcp    CLOSE-WAIT 434    0      10.0.0.1:47931                65.49.18.136:https
>         tcp    CLOSE-WAIT 432    0      10.0.0.1:47932                65.49.18.136:https
>         tcp    CLOSE-WAIT 434    0      10.0.0.1:47931                65.49.18.136:https
>         tcp    CLOSE-WAIT 432    0      10.0.0.1:47932                65.49.18.136:https
> 
> as you can see, there's one duplicate entry of each  tcp  socket,
> however,  if  i  explicitly  specify  tcp socket by adding the -t
> switch,
> 
>         $ ss -t
>         State      Recv-Q Send-Q Local Address:Port                 Peer Address:Port
>         CLOSE-WAIT 434    0      10.0.0.1:47931                65.49.18.136:https
>         CLOSE-WAIT 432    0      10.0.0.1:47932                65.49.18.136:https
> 
> the duplication is gone.
> 
> this problem also occurs on  git  master,  but  not  on  iproute2
> v4.3.0,  so  i  did  a  git bisect and found out the commit which
> caused this is 9f66764e308e9c645b3fb2d1cfbb7fb207eb5de1,  and  by
> revert this commit on git master, i.e. removing
> 
>                                         err = rtnl_dump_done(rth, h);
>                                         if (err < 0)
>                                                 return -1;
> 
> these 3 lines of code of lib/libnetlink.c, the problem is gone.
> 
> since  i'm not familiar with the source code, i doubt this is the
> right way to solve the problem, what's your suggestions? thanks.