netdev - Re: tdc [Was: Re: [PATCH v2 net-next 00/14] net_sched: first series for RTNL-less] qdisc dumps

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Date: Fri, 19 Apr 2024 08:18:09 +0100
From: Simon Horman <horms@...nel.org>
To: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Eric Dumazet <edumazet@...gle.com>,
	"David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Toke Høiland-Jørgensen <toke@...hat.com>,
	Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>,
	netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: tdc [Was: Re: [PATCH v2 net-next 00/14] net_sched: first series
 for RTNL-less] qdisc dumps

On Thu, Apr 18, 2024 at 07:05:08PM -0400, Jamal Hadi Salim wrote:
> On Thu, Apr 18, 2024 at 11:08 AM Simon Horman <horms@...nel.org> wrote:
> >
> > On Thu, Apr 18, 2024 at 06:23:27AM -0400, Jamal Hadi Salim wrote:
> > > On Thu, Apr 18, 2024 at 3:32 AM Eric Dumazet <edumazet@...gle.com> wrote:
> > > >
> > > > Medium term goal is to implement "tc qdisc show" without needing
> > > > to acquire RTNL.
> > > >
> > > > This first series makes the requested changes in 14 qdisc.
> > > >
> > > > Notes :
> > > >
> > > >  - RTNL is still held in "tc qdisc show", more changes are needed.
> > > >
> > > >  - Qdisc returning many attributes might want/need to provide
> > > >    a consistent set of attributes. If that is the case, their
> > > >    dump() method could acquire the qdisc spinlock, to pair the
> > > >    spinlock acquision in their change() method.
> > > >
> > >
> > > For the series:
> > > Reviewed-by: Jamal Hadi Salim<jhs@...atatu.com>
> > >
> > > Not a show-stopper, we'll run the tdc tests after (and use this as an
> > > opportunity to add more tests if needed).
> > > For your next series we'll try to do that after you post.
> >
> > Hi Jamal,
> >
> > On the topic of tdc, I noticed the following both
> > with and without this series applied. Is this something
> > you are aware of?
> >
> > not ok 990 ce7d - Add mq Qdisc to multi-queue device (4 queues)
> >
> 
> Since you said it also happens before Eric's patch, I took a look in
> the test and nothing seems to stand out. Which iproute2 version are
> you using?
> We are running tdc in tandem with net-next (and iproute2-next) via
> nipa for a while now and didn't see this problem pop up. So I am
> guessing something in your setup?

Thanks Jamal,

I appreciate you checking this.
I agree it seems likely that it relates to my environment.
And I'll try out iproute2-next.

For the record I'm using the Fedora 39 packaged iproute2,
iproute-6.4.0-2.fc39.x86_64.

For the kernel, I was using net-next from within the past few days.

> > I'm not sure if it is valid, but I tried running tdc like this:
> >
> > $ ng --build --config tools/testing/selftests/tc-testing/config
> > $ vng -v --run . --user root --cpus 4 -- \
> >         "cd ./tools/testing/selftests/tc-testing; ./tdc.py;"
> 
> This looks reasonable...

Thanks, that was my main question.