Commit d3aeb889 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net/sched: sch_choke: annotate data-races in choke_dump_stats() 



choke_dump_stats() only runs with RTNL held.
It reads fields that can be changed in qdisc fast path.
Add READ_ONCE()/WRITE_ONCE() annotations.

Fixes: edb09eb1 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarJamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260423062839.2524324-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent bde34e84

net/sched/sch_choke.c

+16 −10
Original line number Diff line number Diff line
@@ -229,7 +229,7 @@ static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch, 


		/* Draw a packet at random from queue and compare flow */

		if (choke_match_random(q, skb, &idx)) {

			q->stats.matched++;

			WRITE_ONCE(q->stats.matched, q->stats.matched + 1);

			choke_drop_by_idx(sch, idx, to_free);

			goto congestion_drop;

		}
@@ -241,11 +241,13 @@ static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
			qdisc_qstats_overlimit(sch);

			if (use_harddrop(q) || !use_ecn(q) ||

			    !INET_ECN_set_ce(skb)) {

				q->stats.forced_drop++;

				WRITE_ONCE(q->stats.forced_drop,

					   q->stats.forced_drop + 1);

				goto congestion_drop;

			}



			q->stats.forced_mark++;

			WRITE_ONCE(q->stats.forced_mark,

				   q->stats.forced_mark + 1);

		} else if (++q->vars.qcount) {

			if (red_mark_probability(p, &q->vars, q->vars.qavg)) {

				q->vars.qcount = 0;
@@ -253,11 +255,13 @@ static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch, 


				qdisc_qstats_overlimit(sch);

				if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {

					q->stats.prob_drop++;

					WRITE_ONCE(q->stats.prob_drop,

					           q->stats.prob_drop + 1);

					goto congestion_drop;

				}



				q->stats.prob_mark++;

				WRITE_ONCE(q->stats.prob_mark,

					   q->stats.prob_mark + 1);

			}

		} else

			q->vars.qR = red_random(p);
@@ -272,7 +276,7 @@ static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
		return NET_XMIT_SUCCESS;

	}



	q->stats.pdrop++;

	WRITE_ONCE(q->stats.pdrop, q->stats.pdrop + 1);

	return qdisc_drop(skb, sch, to_free);



congestion_drop:
@@ -461,10 +465,12 @@ static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 
{

	struct choke_sched_data *q = qdisc_priv(sch);

	struct tc_choke_xstats st = {

		.early	= q->stats.prob_drop + q->stats.forced_drop,

		.marked	= q->stats.prob_mark + q->stats.forced_mark,

		.pdrop	= q->stats.pdrop,

		.matched = q->stats.matched,

		.early	= READ_ONCE(q->stats.prob_drop) +

			  READ_ONCE(q->stats.forced_drop),

		.marked	= READ_ONCE(q->stats.prob_mark) +

			  READ_ONCE(q->stats.forced_mark),

		.pdrop	= READ_ONCE(q->stats.pdrop),

		.matched = READ_ONCE(q->stats.matched),

	};



	return gnet_stats_copy_app(d, &st, sizeof(st));