Jamal Hadi Salim <j...@mojatatu.com> wrote:
> On 05/12/15 09:00, Florian Westphal wrote:
> >Jamal Hadi Salim <j...@mojatatu.com> wrote:
> >>Florian,
> >>In general i am in support of removing this - since the use case never
> >>materialized as being useful. However, this is not the same logic that
> >>was there before. To get equivalency you need to pass the limit into
> >>tc_classify_compat() so i can be reset.
> >
> >AFAICS this re-set only happens when we return something other
> >than RECLASSIFY which means the caller will not check the limit.
> >
> >So in fact it should be ok to remove this since the counter will always
> >start from 0 on next tc_classify() invocation.
> >
>
> Florian, consider the following scenario:
> Assume X is the max allowed reclassified before bells start ringing.
> If we see upto X back-to-back reclassify - we are very much likely in
> a loop. We should see fire trucks arrive and bail out.
> If we see X-1 "reclassify" followed by a "pipe" followed by
> X-1 "reclassify" followed by "ok" then that looks like a healthy
> policy. But that is a a total of 2X-2 reclassifies. You will
> bail out at X reclassifies; what i am saying is you shouldnt.
> And existing logic doesnt. Does that make sense?
Yes, but, if we use your example above then:
tc_classify called
limit 0
tc_classify_compat called, ret RECLASSIFY
limit 1
tc_classify_compat called, ret RECLASSIFY
limit 2
tc_classify_compat called, ret PIPE (== 3)
tc_classify returns 3
tc_classify called
limit 0
...
So we don't toss skb since any return value other than RECLASSIFY
will make tc_classify() return to its caller, and when caller invokes
tc_classify again the limit variable is set to 0 again.
Does that make sense to you?
Thanks Jamal.
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