Re: [REGRESSION] Commit 447cbe95ebb9 causes IOMMU DMA faults on macvlan/vlan with bnxt_en
flat view
From: Eric Dumazet <edumazet@kernel.org>
Date: 2026-10-05 01:59:50
Also in:
regressions, stable
Subsystem:
broadcom bnxt_en 50 gigabit ethernet driver, networking drivers, the rest · Maintainers:
Michael Chan, Pavan Chebbi, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
On 10/5/26 00:29, Michael Chan wrote:
I think skb->len is not updated with the padded length here. So the HW will drop the packet seeing that the length is too short. There is another skb_put_padto() that might work better?
+1 Exactly, thanks!
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index d7728d0c5b6e63ee72de9dea54426bb4c8b7a9fc..7ea27e81e88c5ca82a453b449982b791e8acc831 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c@@ -486,7 +486,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) struct netdev_queue *txq; int i; dma_addr_t mapping; - unsigned int length, pad = 0; + unsigned int length; u32 len, free_size, vlan_tag_flags, cfa_action, flags; struct bnxt_ptp_cfg *ptp = bp->ptp_cfg; struct pci_dev *pdev = bp->pdev;
@@ -672,14 +672,12 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) } normal_tx: - if (length < BNXT_MIN_PKT_SIZE) { - pad = BNXT_MIN_PKT_SIZE - length; - if (skb_pad(skb, pad)) - /* SKB already freed. */ - goto tx_kick_pending; - length = BNXT_MIN_PKT_SIZE; + if (skb_put_padto(skb, BNXT_MIN_PKT_SIZE)) { + /* SKB already freed. */ + goto tx_kick_pending; } - + length = skb->len; + len = skb_headlen(skb); mapping = dma_map_single(&pdev->dev, skb->data, len, DMA_TO_DEVICE); if (unlikely(dma_mapping_error(&pdev->dev, mapping)))
@@ -759,10 +757,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) txbd->tx_bd_len_flags_type = cpu_to_le32(flags); } - flags &= ~TX_BD_LEN; - txbd->tx_bd_len_flags_type = - cpu_to_le32(((len + pad) << TX_BD_LEN_SHIFT) | flags | - TX_BD_FLAGS_PACKET_END); + txbd->tx_bd_len_flags_type |= cpu_to_le32(TX_BD_FLAGS_PACKET_END); netdev_tx_sent_queue(txq, skb->len);