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net: airoha: Fix possible TX queue stall in airoha_qdma_tx_napi_poll()

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Since multiple net_device TX queues can share the same hw QDMA TX queue,
there is no guarantee we have inflight packets queued in hw belonging to a
net_device TX queue stopped in the xmit path because hw QDMA TX queue
can be full. In this corner case the net_device TX queue will never be
re-activated. In order to avoid any potential net_device TX queue stall,
we need to wake all the net_device TX queues feeding the same hw QDMA TX
queue in airoha_qdma_tx_napi_poll routine.

Fixes: 23020f0493 ("net: airoha: Introduce ethernet support for EN7581 SoC")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260416-airoha-txq-potential-stall-v2-1-42c732074540@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Lorenzo Bianconi 2026-04-16 12:30:12 +02:00 committed by Jakub Kicinski
parent 2091c6aa0d
commit b94769eb2f
2 changed files with 33 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
drivers/net/ethernet/airoha/airoha_eth.c
View File

@ -843,6 +843,21 @@ static int airoha_qdma_init_rx(struct airoha_qdma *qdma)
return 0; return 0;
} }
static void airoha_qdma_wake_netdev_txqs(struct airoha_queue *q)
{
struct airoha_qdma *qdma = q->qdma;
struct airoha_eth *eth = qdma->eth;
int i;
for (i = 0; i < ARRAY_SIZE(eth->ports); i++) {
struct airoha_gdm_port *port = eth->ports[i];
if (port && port->qdma == qdma)
netif_tx_wake_all_queues(port->dev);
}
q->txq_stopped = false;
}
static int airoha_qdma_tx_napi_poll(struct napi_struct *napi, int budget) static int airoha_qdma_tx_napi_poll(struct napi_struct *napi, int budget)
{ {
struct airoha_tx_irq_queue *irq_q; struct airoha_tx_irq_queue *irq_q;
@ -919,12 +934,21 @@ static int airoha_qdma_tx_napi_poll(struct napi_struct *napi, int budget)
txq = netdev_get_tx_queue(skb->dev, queue); txq = netdev_get_tx_queue(skb->dev, queue);
netdev_tx_completed_queue(txq, 1, skb->len); netdev_tx_completed_queue(txq, 1, skb->len);
if (netif_tx_queue_stopped(txq) &&
q->ndesc - q->queued >= q->free_thr)
netif_tx_wake_queue(txq);
dev_kfree_skb_any(skb); dev_kfree_skb_any(skb);
} }
if (q->txq_stopped && q->ndesc - q->queued >= q->free_thr) {
/* Since multiple net_device TX queues can share the
* same hw QDMA TX queue, there is no guarantee we have
* inflight packets queued in hw belonging to a
* net_device TX queue stopped in the xmit path.
* In order to avoid any potential net_device TX queue
* stall, we need to wake all the net_device TX queues
* feeding the same hw QDMA TX queue.
*/
airoha_qdma_wake_netdev_txqs(q);
}
unlock: unlock:
spin_unlock_bh(&q->lock); spin_unlock_bh(&q->lock);
} }
@ -1984,6 +2008,7 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
if (q->queued + nr_frags >= q->ndesc) { if (q->queued + nr_frags >= q->ndesc) {
/* not enough space in the queue */ /* not enough space in the queue */
netif_tx_stop_queue(txq); netif_tx_stop_queue(txq);
q->txq_stopped = true;
spin_unlock_bh(&q->lock); spin_unlock_bh(&q->lock);
return NETDEV_TX_BUSY; return NETDEV_TX_BUSY;
} }
@ -2039,8 +2064,10 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
TX_RING_CPU_IDX_MASK, TX_RING_CPU_IDX_MASK,
FIELD_PREP(TX_RING_CPU_IDX_MASK, index)); FIELD_PREP(TX_RING_CPU_IDX_MASK, index));
if (q->ndesc - q->queued < q->free_thr) if (q->ndesc - q->queued < q->free_thr) {
netif_tx_stop_queue(txq); netif_tx_stop_queue(txq);
q->txq_stopped = true;
}
spin_unlock_bh(&q->lock); spin_unlock_bh(&q->lock);

1
drivers/net/ethernet/airoha/airoha_eth.h
View File

@ -193,6 +193,7 @@ struct airoha_queue {
int ndesc; int ndesc;
int free_thr; int free_thr;
int buf_size; int buf_size;
bool txq_stopped;
struct napi_struct napi; struct napi_struct napi;
struct page_pool *page_pool; struct page_pool *page_pool;