Commit 8c0cea59 authored by Octavian Purdila's avatar Octavian Purdila Committed by David S. Miller
Browse files

net_sched: sch_sfq: use a temporary work area for validating configuration 



Many configuration parameters have influence on others (e.g. divisor
-> flows -> limit, depth -> limit) and so it is difficult to correctly
do all of the validation before applying the configuration. And if a
validation error is detected late it is difficult to roll back a
partially applied configuration.

To avoid these issues use a temporary work area to update and validate
the configuration and only then apply the configuration to the
internal state.

Signed-off-by: default avatarOctavian Purdila <tavip@google.com>
Acked-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7f1ff1b3

net/sched/sch_sfq.c

+44 −12
Original line number Diff line number Diff line
@@ -631,6 +631,15 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt, 
	struct red_parms *p = NULL;

	struct sk_buff *to_free = NULL;

	struct sk_buff *tail = NULL;

	unsigned int maxflows;

	unsigned int quantum;

	unsigned int divisor;

	int perturb_period;

	u8 headdrop;

	u8 maxdepth;

	int limit;

	u8 flags;





	if (opt->nla_len < nla_attr_size(sizeof(*ctl)))

		return -EINVAL;
@@ -656,35 +665,58 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt, 
		NL_SET_ERR_MSG_MOD(extack, "invalid limit");

		return -EINVAL;

	}



	sch_tree_lock(sch);



	limit = q->limit;

	divisor = q->divisor;

	headdrop = q->headdrop;

	maxdepth = q->maxdepth;

	maxflows = q->maxflows;

	perturb_period = q->perturb_period;

	quantum = q->quantum;

	flags = q->flags;



	/* update and validate configuration */

	if (ctl->quantum)

		q->quantum = ctl->quantum;

	WRITE_ONCE(q->perturb_period, ctl->perturb_period * HZ);

		quantum = ctl->quantum;

	perturb_period = ctl->perturb_period * HZ;

	if (ctl->flows)

		q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);

		maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);

	if (ctl->divisor) {

		q->divisor = ctl->divisor;

		q->maxflows = min_t(u32, q->maxflows, q->divisor);

		divisor = ctl->divisor;

		maxflows = min_t(u32, maxflows, divisor);

	}

	if (ctl_v1) {

		if (ctl_v1->depth)

			q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH);

			maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH);

		if (p) {

			swap(q->red_parms, p);

			red_set_parms(q->red_parms,

			red_set_parms(p,

				      ctl_v1->qth_min, ctl_v1->qth_max,

				      ctl_v1->Wlog,

				      ctl_v1->Plog, ctl_v1->Scell_log,

				      NULL,

				      ctl_v1->max_P);

		}

		q->flags = ctl_v1->flags;

		q->headdrop = ctl_v1->headdrop;

		flags = ctl_v1->flags;

		headdrop = ctl_v1->headdrop;

	}

	if (ctl->limit) {

		q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows);

		q->maxflows = min_t(u32, q->maxflows, q->limit);

	}

		limit = min_t(u32, ctl->limit, maxdepth * maxflows);

		maxflows = min_t(u32, maxflows, limit);

	}



	/* commit configuration */

	q->limit = limit;

	q->divisor = divisor;

	q->headdrop = headdrop;

	q->maxdepth = maxdepth;

	q->maxflows = maxflows;

	WRITE_ONCE(q->perturb_period, perturb_period);

	q->quantum = quantum;

	q->flags = flags;

	if (p)

		swap(q->red_parms, p);



	qlen = sch->q.qlen;

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