netdev - Re: [PATCH] TBF: stop qdisc infanticide

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 13 May 2010 18:30:46 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Stephen Hemminger <shemminger@...tta.com>
CC:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] TBF: stop qdisc infanticide

Stephen Hemminger wrote:
> On Thu, 13 May 2010 18:22:56 +0200
> Patrick McHardy <kaber@...sh.net> wrote:
> 
>> Stephen Hemminger wrote:
>>> Several netem users have complained that when using TBF for rate control
>>> that any change to TBF parameters destroys the child qdisc. A typical
>>> use is to have a test that sets up netem + TBF then changes bandwidth
>>> setting.  But every time the parameters of TBF are changed it destroys
>>> the child qdisc, requiring reconfiguration. Other qdisc's like HTB
>>> don't do this.
>>>
>>> Signed-off-by: Stephen Hemminger <shemminger@...tta.com>
>>>
>>>
>>> --- a/net/sched/sch_tbf.c	2010-05-12 20:41:06.257006386 -0700
>>> +++ b/net/sched/sch_tbf.c	2010-05-12 20:52:35.671216316 -0700
>>> @@ -273,7 +273,11 @@ static int tbf_change(struct Qdisc* sch,
>>>  	if (max_size < 0)
>>>  		goto done;
>>>  
>>> -	if (qopt->limit > 0) {
>>> +	if (q->qdisc) {
>>> +		err = fifo_set_limit(q->qdisc, qopt->limit);
>>> +		if (err)
>>> +			goto done;
>> q->qdisc is never NULL since a noop_qdisc is assigned by default. Also
>> this should check that the child is in fact one of the *fifos.
> 
> But the child will be netem and fifo_set_limit ignores non-fifo.

OK, but it does need to make sure the child is not a noop_qdisc,
otherwise it won't create the default bfifo.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html