On 04-10-2025 15:08, Simon Horman wrote:
On Fri, Oct 03, 2025 at 08:47:24AM -0700, Aditya Garg wrote:
The MANA hardware supports a maximum of 30 scatter-gather entries (SGEs)
per TX WQE. In rare configurations where MAX_SKB_FRAGS + 2 exceeds this
limit, the driver drops the skb. Add a check in mana_start_xmit() to
detect such cases and linearize the SKB before transmission.
Return NETDEV_TX_BUSY only for -ENOSPC from mana_gd_post_work_request(),
send other errors to free_sgl_ptr to free resources and record the tx
drop.
Signed-off-by: Aditya Garg <[email protected]>
Reviewed-by: Dipayaan Roy <[email protected]>
---
drivers/net/ethernet/microsoft/mana/mana_en.c | 26 +++++++++++++++----
include/net/mana/gdma.h | 8 +++++-
include/net/mana/mana.h | 1 +
3 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
b/drivers/net/ethernet/microsoft/mana/mana_en.c
index f4fc86f20213..22605753ca84 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -20,6 +20,7 @@
#include <net/mana/mana.h>
#include <net/mana/mana_auxiliary.h>
+#include <linux/skbuff.h>
static DEFINE_IDA(mana_adev_ida);
@@ -289,6 +290,19 @@ 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 > MANA_MAX_TX_WQE_SGL_ENTRIES)
Hi Aditya,
I see that Eric has made a more substantial review of this patch,
so please follow his advice.
But I wanted to add something to keep in mind for the future: I if the #if
/ #else used here can be replaced by a simple if() statement, then that
would be preferable. The advantage being that it improves compile
coverage. And, as these are all constants, I would expect the compiler to
optimise away any unused code.
Hi Simon,
I will take care of yours and Eric's comment in v2 of this patch.
Regards,
Aditya
