netdev - Re: [PATCH net 1/4] mqprio: Correct stats in mqprio_dump_class

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Message-ID: <20211008163340.5c8ebc2c@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 8 Oct 2021 16:33:40 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Ahmed S. Darwish" <a.darwish@...utronix.de>,
        John Fastabend <john.fastabend@...il.com>
Subject: Re: [PATCH net 1/4] mqprio: Correct stats in
 mqprio_dump_class_stats().

On Thu,  7 Oct 2021 19:49:57 +0200 Sebastian Andrzej Siewior wrote:
> It looks like with the introduction of subqueus the statics broke.
> Before the change `bstats' and `qstats' on stack was fed and later this
> was copied over to struct gnet_dump.
> 
> After the change the `bstats' and `qstats' are only set to 0 and no
> longer updated and that is then fed to gnet_dump. Additionally
> qdisc->cpu_bstats and qdisc->cpu_qstats is destroeyd for global
> stats. For per-CPU stats both __gnet_stats_copy_basic() and
> __gnet_stats_copy_queue() add the values but for global stats the value
> set and so the previous value is lost and only the last value from the
> loop ends up in sch->[bq]stats.
> 
> Use the on-stack [bq]stats variables again and add the stats manually in
> the global case.
> 
> Fixes: ce679e8df7ed2 ("net: sched: add support for TCQ_F_NOLOCK subqueues to sch_mqprio")
> Cc: John Fastabend <john.fastabend@...il.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

Applied after significant massaging of the commit message.

Please repost the cleanup in a week (once net gets merged 
into net-next).

Thanks!