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Commit 95946658 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by David S. Miller
Browse files

net_sched: call qlen_notify only if child qdisc is empty 



This callback is used for deactivating class in parent qdisc.
This is cheaper to test queue length right here.

Also this allows to catch draining screwed backlog and prevent
second deactivation of already inactive parent class which will
crash kernel for sure. Kernel with print warning at destruction
of child qdisc where no packets but backlog is not zero.

Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 869cec99

net/sched/sch_api.c

+9 −1
Original line number Diff line number Diff line
@@ -749,6 +749,7 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, unsigned int n, 
	const struct Qdisc_class_ops *cops;

	unsigned long cl;

	u32 parentid;

	bool notify;

	int drops;



	if (n == 0 && len == 0)
@@ -761,6 +762,13 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, unsigned int n, 


		if (sch->flags & TCQ_F_NOPARENT)

			break;

		/* Notify parent qdisc only if child qdisc becomes empty.

		 *

		 * If child was empty even before update then backlog

		 * counter is screwed and we skip notification because

		 * parent class is already passive.

		 */

		notify = !sch->q.qlen && !WARN_ON_ONCE(!n);

		/* TODO: perform the search on a per txq basis */

		sch = qdisc_lookup(qdisc_dev(sch), TC_H_MAJ(parentid));

		if (sch == NULL) {
@@ -768,7 +776,7 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, unsigned int n, 
			break;

		}

		cops = sch->ops->cl_ops;

		if (cops->qlen_notify) {

		if (notify && cops->qlen_notify) {

			cl = cops->get(sch, parentid);

			cops->qlen_notify(sch, cl);

			cops->put(sch, cl);

net/sched/sch_cbq.c

+1 −2
Original line number Diff line number Diff line
@@ -1385,7 +1385,6 @@ static void cbq_qlen_notify(struct Qdisc *sch, unsigned long arg) 
{

	struct cbq_class *cl = (struct cbq_class *)arg;



	if (cl->q->q.qlen == 0)

	cbq_deactivate_class(cl);

}

net/sched/sch_drr.c

+1 −2
Original line number Diff line number Diff line
@@ -246,7 +246,6 @@ static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) 
{

	struct drr_class *cl = (struct drr_class *)arg;



	if (cl->qdisc->q.qlen == 0)

	list_del(&cl->alist);

}

net/sched/sch_hfsc.c

+2 −4
Original line number Diff line number Diff line
@@ -1221,11 +1221,9 @@ hfsc_qlen_notify(struct Qdisc *sch, unsigned long arg) 
{

	struct hfsc_class *cl = (struct hfsc_class *)arg;



	if (cl->qdisc->q.qlen == 0) {

	update_vf(cl, 0, 0);

	set_passive(cl);

}

}



static unsigned long

hfsc_get_class(struct Qdisc *sch, u32 classid)

net/sched/sch_htb.c

+1 −2
Original line number Diff line number Diff line
@@ -1186,7 +1186,6 @@ static void htb_qlen_notify(struct Qdisc *sch, unsigned long arg) 
{

	struct htb_class *cl = (struct htb_class *)arg;



	if (cl->un.leaf.q->q.qlen == 0)

	htb_deactivate(qdisc_priv(sch), cl);

}