From: Patrick McHardy <kaber@trash•net>
To: Martin Devera <devik@cdi•cz>
Cc: Jarek Poplawski <jarkao2@o2•pl>, netdev@vger•kernel.org
Subject: Re: [NET_SCHED 06/06]: Fix endless loops (part 4): HTB
Date: Thu, 23 Nov 2006 10:48:40 +0100 [thread overview]
Message-ID: <45656E78.6070108@trash.net> (raw)
In-Reply-To: <45656AAB.3080903@cdi.cz>
Martin Devera wrote:
>> In htb_graft it was necessary because the class could be
>> either active (qlen > 0) or inactive (qlen == 0). But since
>> qdisc_tree_decrease_qlen does nothing in case of a decrease
>> of zero the callback is only called for active classes and
>> the check becomes unnecessary.
>>
>
> Patrick is right here. prio_activity for leaf is set in htb's enqueue
> routines. The qlen callback is called when len changed and because
> that zero test in htb's callback it is sure the subclass was nonempty
> before.
BTW, I plan to remove the check for empty child qdiscs in
htb_dequeue_tree and the check for prio_activity after the
calls to qdisc_tree_decrease_len in htb_change_class as a
follow-up patch in 2.6.20, for now I kept them to be safe.
> The only problem might be if some subqdisc "creates" new packets,
> then htb might deactivate non-active class (leading to BUG()).
> IIRC no qdisc does it...
netem can duplicate packets, but it enqueues them at the root,
so it shouldn't be a problem. It might be preferable to do
something similar to qdisc_tree_decrease_qlen in that case to
make sure the packet really ends up in the netem qdisc, but for
now I just wanted to fix the endless loops.
next prev parent reply other threads:[~2006-11-23 9:48 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-20 13:08 [NET_SCHED 00/06]: Fix endless dequeue loops Patrick McHardy
2006-11-20 13:08 ` [NET_SCHED 01/06]: sch_htb: perform qlen adjustment immediately in ->delete Patrick McHardy
2006-11-30 1:35 ` David Miller
2006-11-20 13:08 ` [NET_SCHED 02/06]: Set parent classid in default qdiscs Patrick McHardy
2006-11-30 1:35 ` David Miller
2006-11-20 13:08 ` [NET_SCHED 03/06]: Fix endless loops caused by inaccurate qlen counters (part 1) Patrick McHardy
2006-11-20 14:23 ` Mika Penttilä
2006-11-20 14:31 ` Patrick McHardy
2006-11-20 14:44 ` Mika Penttilä
2006-11-20 14:51 ` Patrick McHardy
2006-11-20 16:07 ` Mika Penttilä
2006-11-20 16:42 ` Patrick McHardy
2006-11-30 1:35 ` David Miller
2006-11-20 13:08 ` [NET_SCHED 04/06]: Fix endless loops (part 2): "simple" qdiscs Patrick McHardy
2006-11-24 12:33 ` Jarek Poplawski
2006-11-24 13:07 ` Patrick McHardy
2006-11-24 13:37 ` Jarek Poplawski
2006-11-27 6:46 ` Jarek Poplawski
2006-11-30 1:36 ` David Miller
2006-11-20 13:08 ` [NET_SCHED 05/06]: Fix endless loops (part 3): HFSC Patrick McHardy
2006-11-30 1:36 ` David Miller
2006-11-20 13:08 ` [NET_SCHED 06/06]: Fix endless loops (part 4): HTB Patrick McHardy
2006-11-20 13:39 ` Martin Devera
2006-11-23 8:39 ` Jarek Poplawski
2006-11-23 8:44 ` Patrick McHardy
2006-11-23 9:01 ` Jarek Poplawski
2006-11-23 9:07 ` Patrick McHardy
2006-11-23 9:32 ` Martin Devera
2006-11-23 9:48 ` Patrick McHardy [this message]
2006-11-23 10:59 ` Jarek Poplawski
2006-11-30 1:37 ` David Miller
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