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net/sched: sch_htb: annotate data-races (II)

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htb_dump_class_stats() will soon run locklessly.
(no RTNL, not qdisc spinlock).

Remove cl->xstats and replace it with two fields:

-	xstats_lends
-	xstats_borrows

Then use READ_ONCE()/WRITE_ONCE() annotations on them, and change
htb_dump_class_stats to use a private struct tc_htb_xstats.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260514095935.3926276-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-05-14 09:59:34 +00:00 committed by Jakub Kicinski
parent e54c33503b
commit 55562d4662
1 changed files with 13 additions and 8 deletions
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21
net/sched/sch_htb.c
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@ -114,7 +114,8 @@ struct htb_class {
*/
struct gnet_stats_basic_sync bstats;
struct gnet_stats_basic_sync bstats_bias;
struct tc_htb_xstats xstats; /* our special stats */
u32 xstats_lends;
u32 xstats_borrows;
/* token bucket parameters */
s64 tokens, ctokens;/* current number of tokens */
@ -707,10 +708,10 @@ static void htb_charge_class(struct htb_sched *q, struct htb_class *cl,
diff = min_t(s64, q->now - cl->t_c, cl->mbuffer);
if (cl->level >= level) {
if (cl->level == level)
cl->xstats.lends++;
WRITE_ONCE(cl->xstats_lends, cl->xstats_lends + 1);
htb_accnt_tokens(cl, bytes, diff);
} else {
cl->xstats.borrows++;
WRITE_ONCE(cl->xstats_borrows, cl->xstats_borrows + 1);
cl->tokens += diff; /* we moved t_c; update tokens */
}
htb_accnt_ctokens(cl, bytes, diff);
@ -1319,6 +1320,10 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
{
struct htb_class *cl = (struct htb_class *)arg;
struct htb_sched *q = qdisc_priv(sch);
struct tc_htb_xstats xstats = {
.lends = READ_ONCE(cl->xstats_lends),
.borrows = READ_ONCE(cl->xstats_borrows),
};
struct gnet_stats_queue qs = {
.drops = cl->drops,
.overlimits = cl->overlimits,
@ -1328,10 +1333,10 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
if (!cl->level && cl->leaf.q)
qdisc_qstats_qlen_backlog(cl->leaf.q, &qlen, &qs.backlog);
cl->xstats.tokens = clamp_t(s64, PSCHED_NS2TICKS(cl->tokens),
INT_MIN, INT_MAX);
cl->xstats.ctokens = clamp_t(s64, PSCHED_NS2TICKS(cl->ctokens),
INT_MIN, INT_MAX);
xstats.tokens = clamp_t(s64, PSCHED_NS2TICKS(cl->tokens),
INT_MIN, INT_MAX);
xstats.ctokens = clamp_t(s64, PSCHED_NS2TICKS(cl->ctokens),
INT_MIN, INT_MAX);
if (q->offload) {
if (!cl->level) {
@ -1352,7 +1357,7 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
gnet_stats_copy_queue(d, NULL, &qs, qlen) < 0)
return -1;
return gnet_stats_copy_app(d, &cl->xstats, sizeof(cl->xstats));
return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
}
static struct netdev_queue *