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Commit 119b3d38 authored by stephen hemminger's avatar stephen hemminger Committed by David S. Miller
Browse files

sfq: deadlock in error path 



The change to allow divisor to be a parameter (in 2.6.38-rc1)
 commit 817fb15d
introduced a possible deadlock caught by sparse.

The scheduler tree lock was left locked in the case of an incorrect
divisor value. Simplest fix is to move test outside of lock
which also solves problem of partial update.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b299e4f0

net/sched/sch_sfq.c

+5 −4
Original line number Diff line number Diff line
@@ -491,17 +491,18 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt) 
	if (opt->nla_len < nla_attr_size(sizeof(*ctl)))

		return -EINVAL;



	if (ctl->divisor &&

	    (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536))

		return -EINVAL;



	sch_tree_lock(sch);

	q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch));

	q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);

	q->perturb_period = ctl->perturb_period * HZ;

	if (ctl->limit)

		q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1);

	if (ctl->divisor) {

		if (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536)

			return -EINVAL;

	if (ctl->divisor)

		q->divisor = ctl->divisor;

	}

	qlen = sch->q.qlen;

	while (sch->q.qlen > q->limit)

		sfq_drop(sch);