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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH][NET_SCHED] sch_api: fix qdisc_tree_decrease_qlen() loop
Date: Mon, 14 Apr 2008 15:11:02 -0700 (PDT)
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From: Patrick McHardy <kaber@trash.net>
Date: Mon, 14 Apr 2008 22:28:52 +0200

> Jarek Poplawski wrote:
> > [NET_SCHED] sch_api: fix qdisc_tree_decrease_qlen() loop
> >
> > TC_H_MAJ(parentid) for root classes is the same as for ingress, and if
> > ingress qdisc is created qdisc_lookup() returns its pointer (without
> > ingress NULL is returned). After this all qdisc_lookups give the same,
> > and we get endless loop. (I don't know how this could hide for so
> > long - it should trigger with every leaf class deleted if it's qdisc
> > isn't empty.)
> >
> > After this fix qdisc_lookup() is omitted both for ingress and root
> > parents, but looking for root is only wasting a little time here...
> > Many thanks to Enrico Demarin for finding a test for catching this
> > bug, which probably bothered quite a lot of admins.
> >   
> 
> Good catch, I agree that this is the reason for sure.

I'll take that as an ACK :-)

Applied, thanks everyone!