net: mana: Enforce TX SGE limit and fix error cleanup
Subsystems (5)
v6 cover net: mana: Enforce TX SGE limit and fix error cleanup
Add pre-transmission checks to block SKBs that exceed the hardware's SGE limit. Force software segmentation for GSO traffic and linearize non-GSO packets as needed.
Update TX error handling to drop failed SKBs and unmap resources immediately.
---
Changes in v6:
* Replace #if logic with constant expression in if().
Changes in v5:
* Drop skb_is_gso() check for disabling GSO in mana_features_check().
* Register .ndo_features_check conditionally to avoid unnecessary call.
Changes in v4:
* Fix warning during build reported by kernel test robot
---
Aditya Garg (2):
net: mana: Handle SKB if TX SGEs exceed hardware limit
net: mana: Drop TX skb on post_work_request failure and unmap
resources
.../net/ethernet/microsoft/mana/gdma_main.c | 6 +-- drivers/net/ethernet/microsoft/mana/mana_en.c | 47 ++++++++++++++++--- .../ethernet/microsoft/mana/mana_ethtool.c | 2 + include/net/mana/gdma.h | 8 +++- include/net/mana/mana.h | 2 + 5 files changed, 53 insertions(+), 12 deletions(-)
Signature · 1 line
2.43.0
PATCH v6 1/2 net: mana: Handle SKB if TX SGEs exceed hardware limit
The MANA hardware supports a maximum of 30 scatter-gather entries (SGEs) per TX WQE. Exceeding this limit can cause TX failures.
Add ndo_features_check() callback to validate SKB layout before transmission. For GSO SKBs that would exceed the hardware SGE limit, clear NETIF_F_GSO_MASK to enforce software segmentation in the stack. Add a fallback in mana_start_xmit() to linearize non-GSO SKBs that still exceed the SGE limit.
Also, Add ethtool counter for SKBs linearized
---
Changes in v6:
* Replace #if logic with constant expression in if().
Changes in v5:
* Drop skb_is_gso() check for disabling GSO in mana_features_check().
* Register .ndo_features_check conditionally to avoid unnecessary call.
Changes in v4:
* No change.
--- drivers/net/ethernet/microsoft/mana/mana_en.c | 40 ++++++++++++++++++- .../ethernet/microsoft/mana/mana_ethtool.c | 2 + include/net/mana/gdma.h | 8 +++- include/net/mana/mana.h | 1 + 4 files changed, 48 insertions(+), 3 deletions(-)
drivers/net/ethernet/microsoft/mana/mana_en.c +38 -2
@@ -11,6 +11,7 @@#include <linux/mm.h> #include <linux/pci.h> #include <linux/export.h> +#include <linux/skbuff.h> #include <net/checksum.h> #include <net/ip6_checksum.h>
@@ -329,6 +330,21 @@ netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev) cq = &apc->tx_qp[txq_idx].tx_cq; tx_stats = &txq->stats; +BUILD_BUG_ON (MAX_TX_WQE_SGL_ENTRIES !=MANA_MAX_TX_WQE_SGL_ENTRIES ); +if (MAX_SKB_FRAGS +2 >MAX_TX_WQE_SGL_ENTRIES && +skb_shinfo (skb)->nr_frags +2 >MAX_TX_WQE_SGL_ENTRIES ) { +/* GSO skb with Hardware SGE limit exceeded is not expected here +* as they are handled in mana_features_check() callback +*/ +if (skb_linearize (skb)) { +netdev_warn_once (ndev,"Failed to linearize skb with nr_frags=%d and is_gso=%d\n" , +skb_shinfo (skb)->nr_frags, +skb_is_gso (skb)); + goto tx_drop_count; + } + apc->eth_stats.tx_linear_pkt_cnt++; + } + pkg.tx_oob.s_oob.vcq_num = cq->gdma_id; pkg.tx_oob.s_oob.vsq_frame = txq->vsq_frame;
@@ -442,8 +458,6 @@ netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev) } } -WARN_ON_ONCE (pkg.wqe_req.num_sge >MAX_TX_WQE_SGL_ENTRIES ); -if (pkg.wqe_req.num_sge <=ARRAY_SIZE (pkg.sgl_array)) { pkg.wqe_req.sgl = pkg.sgl_array; }else {
@@ -518,6 +532,25 @@ netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev)return NETDEV_TX_OK ; } +#if (MAX_SKB_FRAGS +2 >MANA_MAX_TX_WQE_SGL_ENTRIES ) +static netdev_features_t mana_features_check (struct sk_buff *skb, +struct net_device *ndev, +netdev_features_t features) +{ +if (skb_shinfo (skb)->nr_frags +2 >MAX_TX_WQE_SGL_ENTRIES ) { +/* Exceeds HW SGE limit. +* GSO case: +* Disable GSO so the stack will software-segment the skb +* into smaller skbs that fit the SGE budget. +* Non-GSO case: +* The xmit path will attempt skb_linearize() as a fallback. +*/ + features &= ~NETIF_F_GSO_MASK ; + } +return features; +} +#endif +static void mana_get_stats64 (struct net_device *ndev,struct rtnl_link_stats64 *st) {
@@ -883,6 +916,9 @@ static const struct net_device_ops mana_devops = { .ndo_open = mana_open, .ndo_stop = mana_close, .ndo_select_queue = mana_select_queue, +#if (MAX_SKB_FRAGS + 2 > MANA_MAX_TX_WQE_SGL_ENTRIES) + .ndo_features_check = mana_features_check, +#endif .ndo_start_xmit = mana_start_xmit, .ndo_validate_addr = eth_validate_addr, .ndo_get_stats64 = mana_get_stats64,
drivers/net/ethernet/microsoft/mana/mana_ethtool.c +2 -0
@@ -18,6 +18,8 @@ static const struct mana_stats_desc mana_eth_stats[] = { {"tx_cq_err", offsetof(struct mana_ethtool_stats, tx_cqe_err)}, {"tx_cqe_unknown_type", offsetof(struct mana_ethtool_stats, tx_cqe_unknown_type)}, + {"tx_linear_pkt_cnt", offsetof(struct mana_ethtool_stats, + tx_linear_pkt_cnt)}, {"rx_coalesced_err", offsetof(struct mana_ethtool_stats, rx_coalesced_err)}, {"rx_cqe_unknown_type", offsetof(struct mana_ethtool_stats,
include/net/mana/gdma.h +7 -1
@@ -486,6 +486,8 @@ struct gdma_wqe {#define INLINE_OOB_SMALL_SIZE 8#define INLINE_OOB_LARGE_SIZE 24 +#define MANA_MAX_TX_WQE_SGL_ENTRIES 30 +#define MAX_TX_WQE_SIZE 512#define MAX_RX_WQE_SIZE 256
@@ -592,6 +594,9 @@ enum {#define GDMA_DRV_CAP_FLAG_1_HANDLE_RECONFIG_EQE BIT(17)#define GDMA_DRV_CAP_FLAG_1_HW_VPORT_LINK_AWARE BIT(6) +/* Driver supports linearizing the skb when num_sge exceeds hardware limit */ +#define GDMA_DRV_CAP_FLAG_1_SKB_LINEARIZE BIT(20) +/* Driver can send HWC periodically to query stats */ #define GDMA_DRV_CAP_FLAG_1_PERIODIC_STATS_QUERY BIT(21)
@@ -605,7 +610,8 @@ enum {GDMA_DRV_CAP_FLAG_1_SELF_RESET_ON_EQE | \GDMA_DRV_CAP_FLAG_1_HANDLE_RECONFIG_EQE | \GDMA_DRV_CAP_FLAG_1_HW_VPORT_LINK_AWARE | \ - GDMA_DRV_CAP_FLAG_1_PERIODIC_STATS_QUERY) +GDMA_DRV_CAP_FLAG_1_PERIODIC_STATS_QUERY | \ + GDMA_DRV_CAP_FLAG_1_SKB_LINEARIZE) #define GDMA_DRV_CAP_FLAGS2 0
include/net/mana/mana.h +1 -0
@@ -377,6 +377,7 @@ struct mana_ethtool_stats {u64 wake_queue;u64 tx_cqe_err;u64 tx_cqe_unknown_type; +u64 tx_linear_pkt_cnt;u64 rx_coalesced_err;u64 rx_cqe_unknown_type; };
Signature · 1 line
2.43.0
PATCH v6 2/2 net: mana: Drop TX skb on post_work_request failure and unmap resources
In reply to Aditya GargDrop TX packets when posting the work request fails and ensure DMA mappings are always cleaned up.
---
Changes in v6:
* No change.
Changes in v5:
* No change.
Changes in v4:
* Fix warning during build reported by kernel test robot
--- drivers/net/ethernet/microsoft/mana/gdma_main.c | 6 +----- drivers/net/ethernet/microsoft/mana/mana_en.c | 7 +++---- include/net/mana/mana.h | 1 + 3 files changed, 5 insertions(+), 9 deletions(-)
drivers/net/ethernet/microsoft/mana/gdma_main.c +1 -5
@@ -1300,7 +1300,6 @@ int mana_gd_post_work_request(struct gdma_queue *wq, struct gdma_posted_wqe_info *wqe_info) {u32 client_oob_size = wqe_req->inline_oob_size; -struct gdma_context *gc;u32 sgl_data_size;u32 max_wqe_size;u32 wqe_size;
@@ -1330,11 +1329,8 @@ int mana_gd_post_work_request(struct gdma_queue *wq,if (wqe_size > max_wqe_size)return -EINVAL ; -if (wq->monitor_avl_buf && wqe_size >mana_gd_wq_avail_space (wq)) { - gc = wq->gdma_dev->gdma_context; -dev_err (gc->dev,"unsuccessful flow control!\n" ); +if (wq->monitor_avl_buf && wqe_size >mana_gd_wq_avail_space (wq))return -ENOSPC ; - }if (wqe_info) wqe_info->wqe_size_in_bu = wqe_size /GDMA_WQE_BU_SIZE ;
drivers/net/ethernet/microsoft/mana/mana_en.c +3 -4
@@ -492,9 +492,9 @@ netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev)if (err) { (void )skb_dequeue_tail (&txq->pending_skbs); +mana_unmap_skb (skb, apc);netdev_warn (ndev,"Failed to post TX OOB: %d\n" , err); - err =NETDEV_TX_BUSY ; - goto tx_busy; + goto free_sgl_ptr; } err =NETDEV_TX_OK ;
@@ -514,7 +514,6 @@ netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev) tx_stats->bytes += len + ((num_gso_seg -1 ) * gso_hs);u64_stats_update_end (&tx_stats->syncp); -tx_busy:if (netif_tx_queue_stopped (net_txq) &&mana_can_tx (gdma_sq)) {netif_tx_wake_queue (net_txq); apc->eth_stats.wake_queue++;
@@ -1687,7 +1686,7 @@ static int mana_move_wq_tail(struct gdma_queue *wq, u32 num_units)return 0 ; } -static void mana_unmap_skb (struct sk_buff *skb,struct mana_port_context *apc) +void mana_unmap_skb (struct sk_buff *skb,struct mana_port_context *apc) {struct mana_skb_head *ash = (struct mana_skb_head *)skb->head;struct gdma_context *gc = apc->ac->gdma_dev->gdma_context;
include/net/mana/mana.h +1 -0
@@ -593,6 +593,7 @@ int mana_set_bw_clamp(struct mana_port_context *apc, u32 speed,void mana_query_phy_stats (struct mana_port_context *apc);int mana_pre_alloc_rxbufs (struct mana_port_context *apc,int mtu,int num_queues);void mana_pre_dealloc_rxbufs (struct mana_port_context *apc); +void mana_unmap_skb (struct sk_buff *skb,struct mana_port_context *apc);extern const struct ethtool_ops mana_ethtool_ops;extern struct dentry *mana_debugfs_root;
Signature · 1 line
2.43.0
This series was applied to netdev/net-next.git (main) by Jakub Kicinski <[email protected]>:
Hello:
This series was applied to netdev/net-next.git (main) by Jakub Kicinski <[email protected]>:
Quoted 8 lines · On Tue, 18 Nov 2025 03:11:07 -0800 you wrote:
Add pre-transmission checks to block SKBs that exceed the hardware's SGE limit. Force software segmentation for GSO traffic and linearize non-GSO packets as needed.
Update TX error handling to drop failed SKBs and unmap resources immediately.
[...]
Here is the summary with links:
- [net-next,v6,1/2] net: mana: Handle SKB if TX SGEs exceed hardware limit
https://git.kernel.org/netdev/net-next/c/934fa943b537 - [net-next,v6,2/2] net: mana: Drop TX skb on post_work_request failure and unmap resources https://git.kernel.org/netdev/net-next/c/45120304e841
You are awesome, thank you!
Signature · 2 lines
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