netdev - Re: [tc] Invalid JSON output from hfsc qdisc

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Message-ID: <CA+NMeC-EQepcOY4nP8fmRVERjSwL-4qGr2Cmx1kakx2MiC=SNw@mail.gmail.com>
Date: Wed, 11 Feb 2026 13:46:27 -0300
From: Victor Nogueira <victor@...atatu.com>
To: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Andrew Lunn <andrew@...n.ch>, Deren Teo <deren.teo@...look.com>, 
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [tc] Invalid JSON output from hfsc qdisc

On Wed, Feb 11, 2026 at 1:33 PM Jamal Hadi Salim <jhs@...atatu.com> wrote:
>
> On Sat, Feb 7, 2026 at 10:09 AM Andrew Lunn <andrew@...n.ch> wrote:
> >
> > On Sat, Feb 07, 2026 at 02:01:01AM +0000, Deren Teo wrote:
> > > Dear Jamal,
> > >
> > > I apologise if you have received this email twice. My first attempt mistakenly contained an HTML part and so was not delivered to the netdev mailing list. The original content follows.
> > >
> > >
> > > The JSON output for the hfsc qdisc is not parseable when a default class is specified; `hfsc_print_opt` uses `fprintf` to print the default class.
> > >
> > >
> > > Environment:
> > >
> > > - Fedora 42
> > > - Linux 6.19.0-rc4+
> > > - iproute-tc-6.12.0-3.fc42.x86_64
> > >
> > > Reproduce:
> > >
> > > 1. Add a hfsc qdisc with any default class. For example, from the tc-hfsc man page:
> > >     # tc qdisc add dev eth0 root handle 1:0 hfsc default 1
> > >
> > > 2. Show the qdisc with the `-j` flag:
> > >     # tc -j qdisc show dev eth0
> > >
> > > Actual results:
> > >
> > > [{"kind":"hfsc","handle":"1:","root":true,"refcnt":17,"options":{default 1 }}]
> > >
> > > Expected results:
> > >
> > > [{"kind":"hfsc","handle":"1:","root":true,"refcnt":17,"options":{"default":1}}]
> >
>
> Yeah, I do note that iproute2 lacks support for json output for hfsc
> (and a couple of other qdiscs).
> Should be a simple patch.

I am hatching something here.
I'll send a patch soon.

cheers,
Victor