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Message-ID: <20230607101622.bhrentqv2y4c5ewj@skbuf>
Date: Wed, 7 Jun 2023 13:16:22 +0300
From: Vladimir Oltean <vladimir.oltean@....com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
Vinicius Costa Gomes <vinicius.gomes@...el.com>,
linux-kernel@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@...el.com>,
Peilin Ye <yepeilin.cs@...il.com>,
Pedro Tammela <pctammela@...atatu.com>
Subject: Re: [PATCH RESEND net-next 2/5] net/sched: taprio: keep child Qdisc
refcount elevated at 2 in offload mode
On Wed, Jun 07, 2023 at 12:05:19PM +0200, Paolo Abeni wrote:
> Perhaps the above chunk could be:
>
> *old = q->qdiscs[cl - 1];
> if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
> WARN_ON_ONCE(dev_graft_qdisc(dev_queue, new) != *old);
> if (new)
> qdisc_refcount_inc(new);
> if (*old)
> qdisc_put(*old);
> }
>
> (boldly assuming I'm not completely lost, which looks a wild bet ;)
Yeah, could be like that. In full offload mode, q->qdiscs[cl - 1] is
also what's grafted to the TXQ, so the WARN_ON() would be indicative of
a serious bug if it triggered.
> > > BTW, what about including your tests from the cover letter somewhere under tc-testing?
> >
> > I don't know about that. Does it involve adding taprio hw offload to netdevsim,
> > so that both code paths are covered?
>
> I guess I underlooked the needed effort and we could live without new
> tests here.
Let's see how the discussion progresses.
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