netdev - Re: [PATCH net-next 10/14] net_sched: sch_fq_pie: implement lockless fq_pie

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Message-ID: <CANn89iL7nZY61RJhkWXkfa8GdTPgWY6mJ__rWk-eU6wDierG2Q@mail.gmail.com>
Date: Wed, 17 Apr 2024 19:15:40 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: Simon Horman <horms@...nel.org>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Jamal Hadi Salim <jhs@...atatu.com>, 
	Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com
Subject: Re: [PATCH net-next 10/14] net_sched: sch_fq_pie: implement lockless fq_pie_dump()

On Wed, Apr 17, 2024 at 7:13 PM Simon Horman <horms@...nel.org> wrote:
>
> On Mon, Apr 15, 2024 at 01:20:50PM +0000, Eric Dumazet wrote:
> > Instead of relying on RTNL, fq_pie_dump() can use READ_ONCE()
> > annotations, paired with WRITE_ONCE() ones in fq_pie_change().
> >
> > Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> > ---
> >  net/sched/sch_fq_pie.c | 61 +++++++++++++++++++++++-------------------
> >  1 file changed, 34 insertions(+), 27 deletions(-)
> >
> > diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c
>
> ...
>
> > @@ -471,22 +477,23 @@ static int fq_pie_dump(struct Qdisc *sch, struct sk_buff *skb)
> >               return -EMSGSIZE;
> >
> >       /* convert target from pschedtime to us */
> > -     if (nla_put_u32(skb, TCA_FQ_PIE_LIMIT, sch->limit) ||
> > -         nla_put_u32(skb, TCA_FQ_PIE_FLOWS, q->flows_cnt) ||
>
> Hi Eric,
>
> I think you missed the corresponding change for q->flows_cnt
> in fq_pie_change().
>

net/sched/sch_fq_pie.c copied the code I wrote in fq_codel,
q->flows_cnt is set once.