In airoha_dev_select_queue(), the expression: queue = (skb->priority - 1) % AIROHA_NUM_QOS_QUEUES; implicitly converts to unsigned arithmetic: when skb->priority is 0 (the default for unclassified traffic), (0u - 1u) wraps to UINT_MAX, and UINT_MAX % 8 = 7, routing default best-effort packets to the highest-priority QoS queue. This causes QoS inversion where the majority of traffic on a PON gateway starves actual high-priority flows (VoIP, gaming, etc.). Fix by guarding the subtraction: when priority is 0, map to queue 0 (lowest priority), otherwise apply the original (priority - 1) % 8 mapping. Fixes: 2b288b81560b ("net: airoha: Introduce ndo_select_queue callback") Signed-off-by: Wayen --- drivers/net/ethernet/airoha/airoha_eth.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c index 31cdb11cd7..d476ef83c3 100644 --- a/drivers/net/ethernet/airoha/airoha_eth.c +++ b/drivers/net/ethernet/airoha/airoha_eth.c @@ -1933,7 +1933,7 @@ static u16 airoha_dev_select_queue(struct net_device *dev, struct sk_buff *skb, */ channel = netdev_uses_dsa(dev) ? skb_get_queue_mapping(skb) : port->id; channel = channel % AIROHA_NUM_QOS_CHANNELS; - queue = (skb->priority - 1) % AIROHA_NUM_QOS_QUEUES; /* QoS queue */ + queue = skb->priority ? (skb->priority - 1) % AIROHA_NUM_QOS_QUEUES : 0; queue = channel * AIROHA_NUM_QOS_QUEUES + queue; return queue < dev->num_tx_queues ? queue : 0; -- 2.51.0