netdev - Re: [net PATCH] net: sched: Fix for duplicate class dump

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Message-ID: <20181018125742.GE4558@nanopsycho.orion>
Date:   Thu, 18 Oct 2018 14:57:42 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Phil Sutter <phil@....cc>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [net PATCH] net: sched: Fix for duplicate class dump

Thu, Oct 18, 2018 at 10:34:26AM CEST, phil@....cc wrote:
>When dumping classes by parent, kernel would return classes twice:
>
>| # tc qdisc add dev lo root prio
>| # tc class show dev lo
>| class prio 8001:1 parent 8001:
>| class prio 8001:2 parent 8001:
>| class prio 8001:3 parent 8001:
>| # tc class show dev lo parent 8001:
>| class prio 8001:1 parent 8001:
>| class prio 8001:2 parent 8001:
>| class prio 8001:3 parent 8001:
>| class prio 8001:1 parent 8001:
>| class prio 8001:2 parent 8001:
>| class prio 8001:3 parent 8001:
>
>This comes from qdisc_match_from_root() potentially returning the root
>qdisc itself if its handle matched. Though in that case, root's classes
>were already dumped a few lines above.
>
>Fixes: cb395b2010879 ("net: sched: optimize class dumps")
>Signed-off-by: Phil Sutter <phil@....cc>

Reviewed-by: Jiri Pirko <jiri@...lanox.com>