linux-kernel - Re: [BUG] moving fq back to clock monotonic breaks my setup

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Message-ID: <CAA85sZvciuNTc1NM1XbbBCqV-hWwjMZM+0i3vigtzmJ8CpPjHg@mail.gmail.com>
Date:   Thu, 10 Jan 2019 09:25:39 +0100
From:   Ian Kumlien <ian.kumlien@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>, pabeni@...hat.com
Cc:     netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] moving fq back to clock monotonic breaks my setup

On Thu, Jan 10, 2019 at 6:53 AM Eric Dumazet <edumazet@...gle.com> wrote:
> On Wed, Jan 9, 2019 at 4:48 PM Ian Kumlien <ian.kumlien@...il.com> wrote:
> >
> > Hi,
> >
> > Just been trough ~5+ hours of bisecting and eventually actually found
> > the culprit =)
> >
> > commit fb420d5d91c1274d5966917725e71f27ed092a85 (refs/bisect/bad)
> > Author: Eric Dumazet <edumazet@...gle.com>
> > Date:   Fri Sep 28 10:28:44 2018 -0700
> >
> >     tcp/fq: move back to CLOCK_MONOTONIC
> >
> > [--8<--]
> >
> > So this might be because my setup might be "odd".
> >
> > Basically I have a firewall with four nics that uses two of those nics
> > to handle my normal
> > internet connection (firewall/MASQ/NAT) and the other two are assigned
> > to one bridge each.
> >
> > The firewall is also my local caching DNS server and DHCP server,
> > which is also used by the VM:s...
> > But with 4.20 DHCP replies disappeared before entering the bridge - i
> > couldn't even see them in
> > tcpdump! (all nics are ixgbe on a atom soc)
> >
> > I'm currently running a kernel with that patch reversed but I'm also
> > wondering about possible ways
> > forward since I'm reverting a fix from someone else...
>
> I suggest you use netdev@ mailing list instead of lkml
>
> Then, we probably need to clear skb->tstamp in more paths (you are
> mentioning bridge ...)
>
> See commit 8203e2d844d34af247a151d8ebd68553a6e91785 for reference.
>
> Can you try :
>
> diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> index 5372e2042adfe20d3cd039c29057535b2413be61..bd4fa141420c92a44716bd93fcd8aa3d3310203a
> 100644
> --- a/net/bridge/br_forward.c
> +++ b/net/bridge/br_forward.c
> @@ -53,6 +53,7 @@ int br_dev_queue_push_xmit(struct net *net, struct
> sock *sk, struct sk_buff *skb
>                 skb_set_network_header(skb, depth);
>         }
>
> +       skb->tstamp = 0;
>         dev_queue_xmit(skb);
>
>         return 0;

This works, and so does: https://marc.info/?l=linux-netdev&m=154696956604748&w=2

Pointed out by Paolo (tested both separately)