[net-next v9 08/10] net: bnxt: Add SW GSO completion and teardown support

Joe Damato
2026-04-07T22:03:40Z

Update __bnxt_tx_int and bnxt_free_one_tx_ring_skbs to handle SW GSO
segments:

- MID segments: adjust tx_pkts/tx_bytes accounting and skip skb free
(the skb is shared across all segments and freed only once)

- LAST segments: call tso_dma_map_complete() to tear down the IOVA
mapping if one was used. On the fallback path, payload DMA unmapping
is handled by the existing per-BD dma_unmap_len walk.

Both MID and LAST completions advance tx_inline_cons to release the
segment's inline header slot back to the ring.

is_sw_gso is initialized to zero, so the new code paths are not run.

Add logic for feature advertisement and guardrails for ring sizing.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Joe Damato <joe@dama.to>
---
v9:
- Always allocate header buffer for non-HW-USO NICs. Avoids a possible
NULL deref if USO is toggled off and the device is brought down, up,
and USO is re-enabled (suggested by AI).
- Adjust bnxt_min_tx_desc_cnt to take a feature parameter. This is needed
to prevent stale features from being examined (suggested by AI).

v7:
- Dropped Pavan's Reviewed-by because some changes were made.
- Added helper bnxt_min_tx_desc_cnt to avoid repeated code computing
descriptor counts.
- Updated to use tso_dma_map_complete helper instead of calling the DMA
IOVA API directly.

v5:
- Added Pavan's Reviewed-by. No functional changes.

v3:
- completion paths updated to use DMA IOVA APIs to teardown mappings.

rfcv2:
- Update the shared header buffer consumer on TX completion.

drivers/net/ethernet/broadcom/bnxt/bnxt.c | 70 ++++++++++++++++---
.../net/ethernet/broadcom/bnxt/bnxt_ethtool.c | 19 ++++-
drivers/net/ethernet/broadcom/bnxt/bnxt_gso.h | 9 +++
3 files changed, 87 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 74968ca1f4e2..73e692ae2253 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -74,6 +74,8 @@
#include "bnxt_debugfs.h"
#include "bnxt_coredump.h"
#include "bnxt_hwmon.h"
+#include "bnxt_gso.h"
+#include <net/tso.h>

#define BNXT_TX_TIMEOUT (5 * HZ)
#define BNXT_DEF_MSG_ENABLE (NETIF_MSG_DRV | NETIF_MSG_HW | \
@@ -817,12 +819,13 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
bool rc = false;

while (RING_TX(bp, cons) != hw_cons) {
- struct bnxt_sw_tx_bd *tx_buf;
+ struct bnxt_sw_tx_bd *tx_buf, *head_buf;
struct sk_buff *skb;
bool is_ts_pkt;
int j, last;

tx_buf = &txr->tx_buf_ring[RING_TX(bp, cons)];
+ head_buf = tx_buf;
skb = tx_buf->skb;

if (unlikely(!skb)) {
@@ -869,6 +872,20 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
DMA_TO_DEVICE, 0);
}
}
+
+ if (unlikely(head_buf->is_sw_gso)) {
+ txr->tx_inline_cons++;
+ if (head_buf->is_sw_gso == BNXT_SW_GSO_LAST) {
+ tso_dma_map_complete(&pdev->dev,
+ &head_buf->sw_gso_cstate);
+ } else {
+ tx_pkts--;
+ tx_bytes -= skb->len;
+ skb = NULL;
+ }
+ head_buf->is_sw_gso = 0;
+ }
+
if (unlikely(is_ts_pkt)) {
if (BNXT_CHIP_P5(bp)) {
/* PTP worker takes ownership of the skb */
@@ -3412,6 +3429,7 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,

for (i = 0; i < max_idx;) {
struct bnxt_sw_tx_bd *tx_buf = &txr->tx_buf_ring[i];
+ struct bnxt_sw_tx_bd *head_buf = tx_buf;
struct sk_buff *skb;
int j, last;

@@ -3464,7 +3482,17 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,
DMA_TO_DEVICE, 0);
}
}
- dev_kfree_skb(skb);
+ if (head_buf->is_sw_gso) {
+ txr->tx_inline_cons++;
+ if (head_buf->is_sw_gso == BNXT_SW_GSO_LAST) {
+ tso_dma_map_complete(&pdev->dev,
+ &head_buf->sw_gso_cstate);
+ } else {
+ skb = NULL;
+ }
+ }
+ if (skb)
+ dev_kfree_skb(skb);
}
netdev_tx_reset_queue(netdev_get_tx_queue(bp->dev, idx));
}
@@ -3990,9 +4018,9 @@ static void bnxt_free_tx_inline_buf(struct bnxt_tx_ring_info *txr,
txr->tx_inline_size = 0;
}

-static int __maybe_unused bnxt_alloc_tx_inline_buf(struct bnxt_tx_ring_info *txr,
- struct pci_dev *pdev,
- unsigned int size)
+static int bnxt_alloc_tx_inline_buf(struct bnxt_tx_ring_info *txr,
+ struct pci_dev *pdev,
+ unsigned int size)
{
txr->tx_inline_buf = kmalloc(size, GFP_KERNEL);
if (!txr->tx_inline_buf)
@@ -4095,6 +4123,13 @@ static int bnxt_alloc_tx_rings(struct bnxt *bp)
sizeof(struct tx_push_bd);
txr->data_mapping = cpu_to_le64(mapping);
}
+ if (!(bp->flags & BNXT_FLAG_UDP_GSO_CAP)) {
+ rc = bnxt_alloc_tx_inline_buf(txr, pdev,
+ BNXT_SW_USO_MAX_SEGS *
+ TSO_HEADER_SIZE);
+ if (rc)
+ return rc;
+ }
qidx = bp->tc_to_qidx[j];
ring->queue_id = bp->q_info[qidx].queue_id;
spin_lock_init(&txr->xdp_tx_lock);
@@ -4633,10 +4668,13 @@ static int bnxt_init_rx_rings(struct bnxt *bp)

static int bnxt_init_tx_rings(struct bnxt *bp)
{
+ netdev_features_t features;
u16 i;

+ features = bp->dev->features;
+
bp->tx_wake_thresh = max_t(int, bp->tx_ring_size / 2,
- BNXT_MIN_TX_DESC_CNT);
+ bnxt_min_tx_desc_cnt(bp, features));

for (i = 0; i < bp->tx_nr_rings; i++) {
struct bnxt_tx_ring_info *txr = &bp->tx_ring[i];
@@ -13835,6 +13873,11 @@ static netdev_features_t bnxt_fix_features(struct net_device *dev,
if ((features & NETIF_F_NTUPLE) && !bnxt_rfs_capable(bp, false))
features &= ~NETIF_F_NTUPLE;

+ if ((features & NETIF_F_GSO_UDP_L4) &&
+ !(bp->flags & BNXT_FLAG_UDP_GSO_CAP) &&
+ bp->tx_ring_size < 2 * BNXT_SW_USO_MAX_DESCS)
+ features &= ~NETIF_F_GSO_UDP_L4;
+
if ((bp->flags & BNXT_FLAG_NO_AGG_RINGS) || bp->xdp_prog)
features &= ~(NETIF_F_LRO | NETIF_F_GRO_HW);

@@ -13880,6 +13923,9 @@ static int bnxt_set_features(struct net_device *dev, netdev_features_t features)
int rc = 0;
bool re_init = false;

+ bp->tx_wake_thresh = max_t(int, bp->tx_ring_size / 2,
+ bnxt_min_tx_desc_cnt(bp, features));
+
flags &= ~BNXT_FLAG_ALL_CONFIG_FEATS;
if (features & NETIF_F_GRO_HW)
flags |= BNXT_FLAG_GRO;
@@ -16905,8 +16951,7 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
NETIF_F_GSO_UDP_TUNNEL_CSUM | NETIF_F_GSO_GRE_CSUM |
NETIF_F_GSO_PARTIAL | NETIF_F_RXHASH |
NETIF_F_RXCSUM | NETIF_F_GRO;
- if (bp->flags & BNXT_FLAG_UDP_GSO_CAP)
- dev->hw_features |= NETIF_F_GSO_UDP_L4;
+ dev->hw_features |= NETIF_F_GSO_UDP_L4;

if (BNXT_SUPPORTS_TPA(bp))
dev->hw_features |= NETIF_F_LRO;
@@ -16939,8 +16984,15 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
dev->priv_flags |= IFF_UNICAST_FLT;

netif_set_tso_max_size(dev, GSO_MAX_SIZE);
- if (bp->tso_max_segs)
+ if (!(bp->flags & BNXT_FLAG_UDP_GSO_CAP)) {
+ u16 max_segs = BNXT_SW_USO_MAX_SEGS;
+
+ if (bp->tso_max_segs)
+ max_segs = min_t(u16, max_segs, bp->tso_max_segs);
+ netif_set_tso_max_segs(dev, max_segs);
+ } else if (bp->tso_max_segs) {
netif_set_tso_max_segs(dev, bp->tso_max_segs);
+ }

dev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
NETDEV_XDP_ACT_RX_SG;
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 6826bf762d26..9ded88196bb4 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -33,6 +33,7 @@
#include "bnxt_xdp.h"
#include "bnxt_ptp.h"
#include "bnxt_ethtool.h"
+#include "bnxt_gso.h"
#include "bnxt_nvm_defs.h" /* NVRAM content constant and structure defs */
#include "bnxt_fw_hdr.h" /* Firmware hdr constant and structure defs */
#include "bnxt_coredump.h"
@@ -852,12 +853,18 @@ static int bnxt_set_ringparam(struct net_device *dev,
u8 tcp_data_split = kernel_ering->tcp_data_split;
struct bnxt *bp = netdev_priv(dev);
u8 hds_config_mod;
+ int rc;

if ((ering->rx_pending > BNXT_MAX_RX_DESC_CNT) ||
(ering->tx_pending > BNXT_MAX_TX_DESC_CNT) ||
(ering->tx_pending < BNXT_MIN_TX_DESC_CNT))
return -EINVAL;

+ if ((dev->features & NETIF_F_GSO_UDP_L4) &&
+ !(bp->flags & BNXT_FLAG_UDP_GSO_CAP) &&
+ ering->tx_pending < 2 * BNXT_SW_USO_MAX_DESCS)
+ return -EINVAL;
+
hds_config_mod = tcp_data_split != dev->cfg->hds_config;
if (tcp_data_split == ETHTOOL_TCP_DATA_SPLIT_DISABLED && hds_config_mod)
return -EINVAL;
@@ -882,9 +889,17 @@ static int bnxt_set_ringparam(struct net_device *dev,
bp->tx_ring_size = ering->tx_pending;
bnxt_set_ring_params(bp);

- if (netif_running(dev))
- return bnxt_open_nic(bp, false, false);
+ if (netif_running(dev)) {
+ rc = bnxt_open_nic(bp, false, false);
+ if (rc)
+ return rc;
+ }

+ /* ring size changes may affect features (SW USO requires a minimum
+ * ring size), so recalculate features to ensure the correct features
+ * are blocked/available.
+ */
+ netdev_update_features(dev);
return 0;
}

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.h b/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.h
index f01e8102dcd7..3bee626a6303 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_gso.h
@@ -23,6 +23,15 @@
*/
#define BNXT_SW_USO_MAX_DESCS (3 * BNXT_SW_USO_MAX_SEGS + MAX_SKB_FRAGS + 1)

+static inline int bnxt_min_tx_desc_cnt(struct bnxt *bp,
+ netdev_features_t features)
+{
+ if (!(bp->flags & BNXT_FLAG_UDP_GSO_CAP) &&
+ (features & NETIF_F_GSO_UDP_L4))
+ return BNXT_SW_USO_MAX_DESCS;
+ return BNXT_MIN_TX_DESC_CNT;
+}
+
netdev_tx_t bnxt_sw_udp_gso_xmit(struct bnxt *bp,
struct bnxt_tx_ring_info *txr,
struct netdev_queue *txq,
--
2.52.0