Subject: Re: [PATCH] Traffic control cgroups subsystem

From: Patrick McHardy <[email-masked]>
Date: Thu, 24 Jul 2008 00:34:24 +0200

Andrew Morton wrote:
> On Tue, 22 Jul 2008 10:44:18 -0700 (PDT)
> Ranjit Manomohan <[email-masked]> wrote:
> 
>> @@ -359,7 +370,12 @@ static int flow_classify(struct sk_buff *skb, struct tcf_proto *tp,
>>   			classid %= f->divisor;
>>
>>   		res->class   = 0;
>> -		res->classid = TC_H_MAKE(f->baseclass, f->baseclass + classid);
>> +
>> +		if (key == FLOW_KEY_CGROUP_CLASSID)
>> +			res->classid = TC_H_MAKE(f->baseclass, classid);
>> +		else
>> +			res->classid = TC_H_MAKE(f->baseclass,
>> +						 f->baseclass + classid);
> 
> This causes a warning:
> 
> net/sched/cls_flow.c: In function 'flow_classify':
> net/sched/cls_flow.c:344: warning: 'key' may be used uninitialized in this function
> 
> that warning is a non-issue if we happen to know that f->nkeys can
> never be zero.  I don't know if that is guaranteed at this code site?

It is by the flow_change() function, but special casing the
CGROUP_CLASSID is not acceptable anyway. There should be no
need for that, a simple linear mapping to classids is done
by default in mapping mode, the sk_cgroup_classid simply
shouldn't include qdisc IDs.