[BUG] net/sched : qlen can not really be per cpu ?

[Eric Dumazet]

HTB + pfifo_fast as a leaf qdisc hits badly the following warning in 
htb_activate() :

WARN_ON(cl->level || !cl->leaf.q || !cl->leaf.q->q.qlen);

This is because pfifo_fast does not update sch->q.qlen, but per cpu counters.
So cl->leaf.q->q.qlen is zero.

HFSC, CBQ, DRR, QFQ  have the same problem.

Any ideas how we can fix this ?

Thanks !