[PATCH net-next 2/4] net/sched: sch_htb: annotate data-races (I)

[Eric Dumazet <edumazet@google.com>]

htb_dump() runs without holding qdisc spinlock.

Add missing READ_ONCE()/WRITE_ONCE() annotations around
q->overlimits and q->direct_pkts.

Fixes: edb09eb17ed8 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump")
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/sched/sch_htb.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 873337ac1cca28ea1a32778d8e91cacb5bd3af9c..5bf1889bc0300e8e3a61d56ddcf1bb1402955107 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -568,7 +568,7 @@ htb_change_class_mode(struct htb_sched *q, struct htb_class *cl, s64 *diff)
 
 	if (new_mode == HTB_CANT_SEND) {
 		cl->overlimits++;
-		q->overlimits++;
+		WRITE_ONCE(q->overlimits, q->overlimits + 1);
 	}
 
 	if (cl->prio_activity) {	/* not necessary: speed optimization */
@@ -628,7 +628,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 		/* enqueue to helper queue */
 		if (q->direct_queue.qlen < q->direct_qlen) {
 			__qdisc_enqueue_tail(skb, &q->direct_queue);
-			q->direct_pkts++;
+			WRITE_ONCE(q->direct_pkts, q->direct_pkts + 1);
 		} else {
 			return qdisc_drop(skb, sch, to_free);
 		}
@@ -1208,12 +1208,12 @@ static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
 	struct nlattr *nest;
 	struct tc_htb_glob gopt;
 
-	sch->qstats.overlimits = q->overlimits;
+	sch->qstats.overlimits = READ_ONCE(q->overlimits);
 	/* Its safe to not acquire qdisc lock. As we hold RTNL,
 	 * no change can happen on the qdisc parameters.
 	 */
 
-	gopt.direct_pkts = q->direct_pkts;
+	gopt.direct_pkts = READ_ONCE(q->direct_pkts);
 	gopt.version = HTB_VER;
 	gopt.rate2quantum = q->rate2quantum;
 	gopt.defcls = q->defcls;
-- 
2.54.0.563.g4f69b47b94-goog