Re: [PATCH] net/sched/sch_hfsc.c: initialize parent's cl_cfmin properly in init_vf()

[David Miller <davem@davemloft.net>]

From: Patrick McHardy <kaber@trash.net>
Date: Wed, 15 Sep 2010 19:54:49 +0200

> Am 01.09.2010 23:30, schrieb David Miller:
>> From: Michal Soltys <soltys@ziu.info>
>> Date: Mon, 30 Aug 2010 23:34:10 +0200
>> 
>>> This patch fixes init_vf() function, so on each new backlog period parent's
>>> cl_cfmin is properly updated (including further propgation towards the root),
>>> even if the activated leaf has no upperlimit curve defined.
>>>
>>> Signed-off-by: Michal Soltys <soltys@ziu.info>
>> 
>> Applied, thanks.
> 
> For the record, the patch seems fine to me. The root cause seems to be
> an optimization I introduced (pre-git, even history.git unfortunately)
> in vttree_get_minvt() that wasn't present in the original version:
> 
> static struct hfsc_class *
> vttree_get_minvt(struct hfsc_class *cl, u64 cur_time)
> {
>         /* if root-class's cfmin is bigger than cur_time nothing to do */
>         if (cl->cl_cfmin > cur_time)
>                 return NULL;

Actually, the HFSC scheduler was added with this test present.
The function had a different name, actlist_get_minvt(), at the
time.  See commit:

commit 6e22ce74ea0666a869ce82f418ce78b5be089fb4
Author: Patrick McHardy <kaber@trash.net>
Date:   Wed Jan 28 20:15:03 2004 -0800

    [NET_SCHED]: Add HFSC packet scheduler.

in the history-2.6 GIT tree.