net/sched: sch_htb: fix htb_dump_class_stats() vs offload mode

htb_dump_class_stats() and htb_offload_aggregate_stats()
call gnet_stats_basic_sync_init(&cl->bstats) which
is wrong on 32bit arches when syncp is cleared.

Make sure to acquire qdisc spinlock and use
_bstats_set() to ease future lockless dumps.

Fixes: 83271586249c ("sch_htb: Stats for offloaded HTB")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Maxim Mikityanskiy <maximmi@mellanox.com>
Cc: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260518090518.629245-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index d8ef3efbe0d5eab42c535e48d95d9005ac9682be..908b9ba9ba2efa8df396b51d437a714afc802a73 100644 (file)
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1293,8 +1293,6 @@ static void htb_offload_aggregate_stats(struct htb_sched *q,
        struct htb_class *c;
        unsigned int i;
 
-       gnet_stats_basic_sync_init(&cl->bstats);
-
        for (i = 0; i < q->clhash.hashsize; i++) {
                hlist_for_each_entry(c, &q->clhash.hash[i], common.hnode) {
                        struct htb_class *p = c;
@@ -1313,7 +1311,7 @@ static void htb_offload_aggregate_stats(struct htb_sched *q,
                        }
                }
        }
-       _bstats_update(&cl->bstats, bytes, packets);
+       _bstats_set(&cl->bstats, bytes, packets);
 }
 
 static int
@@ -1340,17 +1338,21 @@ htb_dump_class_stats(struct Qdisc *sch, unsigned long arg, struct gnet_dump *d)
                                 INT_MIN, INT_MAX);
 
        if (q->offload) {
+               spin_lock_bh(qdisc_lock(sch));
                if (!cl->level) {
-                       if (cl->leaf.q)
-                               cl->bstats = cl->leaf.q->bstats;
-                       else
-                               gnet_stats_basic_sync_init(&cl->bstats);
-                       _bstats_update(&cl->bstats,
-                                      u64_stats_read(&cl->bstats_bias.bytes),
-                                      u64_stats_read(&cl->bstats_bias.packets));
+                       u64 bytes = 0, packets = 0;
+
+                       if (cl->leaf.q) {
+                               bytes = u64_stats_read(&cl->leaf.q->bstats.bytes);
+                               packets = u64_stats_read(&cl->leaf.q->bstats.packets);
+                       }
+                       bytes += u64_stats_read(&cl->bstats_bias.bytes);
+                       packets += u64_stats_read(&cl->bstats_bias.packets);
+                       _bstats_set(&cl->bstats, bytes, packets);
                } else {
                        htb_offload_aggregate_stats(q, cl);
                }
+               spin_unlock_bh(qdisc_lock(sch));
        }
 
        if (gnet_stats_copy_basic(d, NULL, &cl->bstats, true) < 0 ||