net_sched: sch_fq: clear q->band_pkt_count[] in fq_reset()

[ Upstream commit a4c2b8b ]

When/if a NIC resets, queues are deactivated by dev_deactivate_many(),
then reactivated when the reset operation completes.

fq_reset() removes all the skbs from various queues.

If we do not clear q->band_pkt_count[], these counters keep growing
and can eventually reach sch->limit, preventing new packets to be queued.

Many thanks to Praveen for discovering the root cause.

Fixes: 29f834a ("net_sched: sch_fq: add 3 bands and WRR scheduling")
Diagnosed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260304015640.961780-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: edumazet

net/sched/sch_fq.c

@@ -829,6 +829,7 @@ static void fq_reset(struct Qdisc *sch)
 	for (idx = 0; idx < FQ_BANDS; idx++) {
 		q->band_flows[idx].new_flows.first = NULL;
 		q->band_flows[idx].old_flows.first = NULL;
+		q->band_pkt_count[idx] = 0;
 	}
 	q->delayed		= RB_ROOT;
 	q->flows		= 0;