[PATCH net v2] net: airoha: Move entries to queue head in case of DMA mapping failure in airoha_dev_xmit()

[Lorenzo Bianconi <lorenzo@kernel.org>]

In order to respect the original descriptor order and avoid any
potential IOMMU fault or memory corruption, move pending queue entries
to the head of hw queue tx_list if the DMA mapping of current inflight
packet fails in airoha_dev_xmit routine.

Fixes: 3f47e67dff1f7 ("net: airoha: Add the capability to consume out-of-order DMA tx descriptors")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Changes in v2:
- Remove leftover airoha_queue_entry initialization inside the loop from
  the previous version.
- Link to v1: https://lore.kernel.org/r/20260428-airoha-xmit-unmap-error-path-v1-1-aec44c6765c1@kernel.org
---
 drivers/net/ethernet/airoha/airoha_eth.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 5effb4a4ae84..fb4f51d67dd7 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -2123,14 +2123,12 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
 	return NETDEV_TX_OK;
 
 error_unmap:
-	while (!list_empty(&tx_list)) {
-		e = list_first_entry(&tx_list, struct airoha_queue_entry,
-				     list);
+	list_for_each_entry(e, &tx_list, list) {
 		dma_unmap_single(dev->dev.parent, e->dma_addr, e->dma_len,
 				 DMA_TO_DEVICE);
 		e->dma_addr = 0;
-		list_move_tail(&e->list, &q->tx_list);
 	}
+	list_splice(&tx_list, &q->tx_list);
 
 	spin_unlock_bh(&q->lock);
 error:

---
base-commit: 0c7a5ba011d336df4fcd1f667fcc16ea5549be12
change-id: 20260428-airoha-xmit-unmap-error-path-8125594efb23

Best regards,
-- 
Lorenzo Bianconi <lorenzo@kernel.org>