Commit c5f1dde7 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net_sched: sch_ets: implement lockless ets_dump() 



Instead of relying on RTNL, ets_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in ets_change().

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a1ac3a7c

net/sched/sch_ets.c

+14 −11
Original line number Diff line number Diff line
@@ -646,7 +646,7 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt, 


	sch_tree_lock(sch);



	q->nbands = nbands;

	WRITE_ONCE(q->nbands, nbands);

	for (i = nstrict; i < q->nstrict; i++) {

		if (q->classes[i].qdisc->q.qlen) {

			list_add_tail(&q->classes[i].alist, &q->active);
@@ -658,11 +658,11 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt, 
			list_del(&q->classes[i].alist);

		qdisc_tree_flush_backlog(q->classes[i].qdisc);

	}

	q->nstrict = nstrict;

	WRITE_ONCE(q->nstrict, nstrict);

	memcpy(q->prio2band, priomap, sizeof(priomap));



	for (i = 0; i < q->nbands; i++)

		q->classes[i].quantum = quanta[i];

		WRITE_ONCE(q->classes[i].quantum, quanta[i]);



	for (i = oldbands; i < q->nbands; i++) {

		q->classes[i].qdisc = queues[i];
@@ -676,7 +676,7 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt, 
	for (i = q->nbands; i < oldbands; i++) {

		qdisc_put(q->classes[i].qdisc);

		q->classes[i].qdisc = NULL;

		q->classes[i].quantum = 0;

		WRITE_ONCE(q->classes[i].quantum, 0);

		q->classes[i].deficit = 0;

		gnet_stats_basic_sync_init(&q->classes[i].bstats);

		memset(&q->classes[i].qstats, 0, sizeof(q->classes[i].qstats));
@@ -733,6 +733,7 @@ static int ets_qdisc_dump(struct Qdisc *sch, struct sk_buff *skb) 
	struct ets_sched *q = qdisc_priv(sch);

	struct nlattr *opts;

	struct nlattr *nest;

	u8 nbands, nstrict;

	int band;

	int prio;

	int err;
@@ -745,21 +746,22 @@ static int ets_qdisc_dump(struct Qdisc *sch, struct sk_buff *skb) 
	if (!opts)

		goto nla_err;



	if (nla_put_u8(skb, TCA_ETS_NBANDS, q->nbands))

	nbands = READ_ONCE(q->nbands);

	if (nla_put_u8(skb, TCA_ETS_NBANDS, nbands))

		goto nla_err;



	if (q->nstrict &&

	    nla_put_u8(skb, TCA_ETS_NSTRICT, q->nstrict))

	nstrict = READ_ONCE(q->nstrict);

	if (nstrict && nla_put_u8(skb, TCA_ETS_NSTRICT, nstrict))

		goto nla_err;



	if (q->nbands > q->nstrict) {

	if (nbands > nstrict) {

		nest = nla_nest_start(skb, TCA_ETS_QUANTA);

		if (!nest)

			goto nla_err;



		for (band = q->nstrict; band < q->nbands; band++) {

		for (band = nstrict; band < nbands; band++) {

			if (nla_put_u32(skb, TCA_ETS_QUANTA_BAND,

					q->classes[band].quantum))

					READ_ONCE(q->classes[band].quantum)))

				goto nla_err;

		}
@@ -771,7 +773,8 @@ static int ets_qdisc_dump(struct Qdisc *sch, struct sk_buff *skb) 
		goto nla_err;



	for (prio = 0; prio <= TC_PRIO_MAX; prio++) {

		if (nla_put_u8(skb, TCA_ETS_PRIOMAP_BAND, q->prio2band[prio]))

		if (nla_put_u8(skb, TCA_ETS_PRIOMAP_BAND,

			       READ_ONCE(q->prio2band[prio])))

			goto nla_err;

	}