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Commit 68a66d14 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by David S. Miller
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net_sched: fix order of queue length updates in qdisc_replace() 



This important to call qdisc_tree_reduce_backlog() after changing queue
length. Parent qdisc should deactivate class in ->qlen_notify() called from
qdisc_tree_reduce_backlog() but this happens only if qdisc->q.qlen in zero.

Missed class deactivations leads to crashes/warnings at picking packets
from empty qdisc and corrupting state at reactivating this class in future.

Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 86a7996c ("net_sched: introduce qdisc_replace() helper")
Acked-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 49bf4b36

include/net/sch_generic.h

+4 −1
Original line number Diff line number Diff line
@@ -806,8 +806,11 @@ static inline struct Qdisc *qdisc_replace(struct Qdisc *sch, struct Qdisc *new, 
	old = *pold;

	*pold = new;

	if (old != NULL) {

		qdisc_tree_reduce_backlog(old, old->q.qlen, old->qstats.backlog);

		unsigned int qlen = old->q.qlen;

		unsigned int backlog = old->qstats.backlog;



		qdisc_reset(old);

		qdisc_tree_reduce_backlog(old, qlen, backlog);

	}

	sch_tree_unlock(sch);