[PATCH] net/mlx5: fix TxQ failure when inlining is impossible

[PATCH] net/mlx5: fix TxQ failure when inlining is impossible

[Dmitry Kozlyuk]

When txq_inline_max is too large and an mbuf is multi-segment
it may be impossible to inline data and build a valid WQE,
because WQE length would be larger then HW can represent.
It is impossible to detect misconfiguration at startup,
because the condition depends on the mbuf composition.
The check on the data path to prevent the error
treated the length limit as expressed in 64B units,
while the calculated length and limit are in 16B units.
Fix the condition to avoid subsequent TxQ failure and recovery.

Fixes: 18a1c20044c0 ("net/mlx5: implement Tx burst template")
Cc: stable@dpdk.org

Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 drivers/net/mlx5/mlx5_tx.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5_tx.h b/drivers/net/mlx5/mlx5_tx.h
index 89dac0c65a..dfa04612ff 100644
--- a/drivers/net/mlx5/mlx5_tx.h
+++ b/drivers/net/mlx5/mlx5_tx.h
@@ -2070,7 +2070,7 @@ mlx5_tx_packet_multi_inline(struct mlx5_txq_data *__rte_restrict txq,
 	if (unlikely(loc->wqe_free < ((ds + 3) / 4)))
 		return MLX5_TXCMP_CODE_EXIT;
 	/* Check for maximal WQE size. */
-	if (unlikely((MLX5_WQE_SIZE_MAX / MLX5_WSEG_SIZE) < ((ds + 3) / 4)))
+	if (unlikely((MLX5_WQE_SIZE_MAX / MLX5_WSEG_SIZE) < ds))
 		return MLX5_TXCMP_CODE_ERROR;
 #ifdef MLX5_PMD_SOFT_COUNTERS
 	/* Update sent data bytes/packets counters. */
-- 
2.25.1

RE: [PATCH] net/mlx5: fix TxQ failure when inlining is impossible

[Raslan Darawsheh]

Hi,
> -----Original Message-----
> From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> Sent: Thursday, March 31, 2022 5:39 PM
> To: dev@dpdk.org
> Cc: stable@dpdk.org; Slava Ovsiienko <viacheslavo@nvidia.com>; Matan
> Azrad <matan@nvidia.com>
> Subject: [PATCH] net/mlx5: fix TxQ failure when inlining is impossible
> 
> When txq_inline_max is too large and an mbuf is multi-segment it may be
> impossible to inline data and build a valid WQE, because WQE length would
> be larger then HW can represent.
> It is impossible to detect misconfiguration at startup, because the condition
> depends on the mbuf composition.
> The check on the data path to prevent the error treated the length limit as
> expressed in 64B units, while the calculated length and limit are in 16B units.
> Fix the condition to avoid subsequent TxQ failure and recovery.
> 
> Fixes: 18a1c20044c0 ("net/mlx5: implement Tx burst template")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

Patch applied to next-net-mlx,

Kindest regards,
Raslan Darawsheh