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Commit d32ae76f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

sch_qfq: accurate wsum handling 



We can underestimate q->wsum in case of "tc class replace ... qfq"
and/or qdisc_create_dflt() error.

wsum is not really used in fast path, only at qfq qdisc/class setup,
to catch user error.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d47a0ac7

net/sched/sch_qfq.c

+9 −8
Original line number Diff line number Diff line
@@ -211,6 +211,7 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 
	struct nlattr *tb[TCA_QFQ_MAX + 1];

	u32 weight, lmax, inv_w;

	int i, err;

	int delta_w;



	if (tca[TCA_OPTIONS] == NULL) {

		pr_notice("qfq: no options\n");
@@ -232,9 +233,10 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 


	inv_w = ONE_FP / weight;

	weight = ONE_FP / inv_w;

	if (q->wsum + weight > QFQ_MAX_WSUM) {

	delta_w = weight - (cl ? ONE_FP / cl->inv_w : 0);

	if (q->wsum + delta_w > QFQ_MAX_WSUM) {

		pr_notice("qfq: total weight out of range (%u + %u)\n",

			  weight, q->wsum);

			  delta_w, q->wsum);

		return -EINVAL;

	}
@@ -256,13 +258,12 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 
				return err;

		}



		if (inv_w != cl->inv_w) {

			sch_tree_lock(sch);

		if (tb[TCA_QFQ_WEIGHT]) {

			q->wsum = weight - ONE_FP / cl->inv_w;

			q->wsum += delta_w;

			cl->inv_w = inv_w;

		}

			sch_tree_unlock(sch);



		}

		return 0;

	}
@@ -277,7 +278,6 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 
	i = qfq_calc_index(cl->inv_w, cl->lmax);



	cl->grp = &q->groups[i];

	q->wsum += weight;



	cl->qdisc = qdisc_create_dflt(sch->dev_queue,

				      &pfifo_qdisc_ops, classid);
@@ -294,6 +294,7 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 
			return err;

		}

	}

	q->wsum += weight;



	sch_tree_lock(sch);

	qdisc_class_hash_insert(&q->clhash, &cl->common);