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: edb09eb17ed8 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260423062839.2524324-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
index 94df8e741a979191a06885ad3ee813f12650ff3c..2875bcdb18a413075c795665e95f9dbbaac45962 100644 (file)
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -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));