[PATCH] net/mlx5: fix decreasing the reference count of a Tx queue

[PATCH] net/mlx5: fix decreasing the reference count of a Tx queue

[Bing Zhao]

When changing the order of the Tx queues startup, the depth of the
queue is compared. If not equal to the current big log2 value, next
queue will be checked and the current one will be skipped for the
next iteration.

The mlx5_txq_get() will increase the reference count number, and the
size check no match is not an error and the startup will continue but
not fall into the error roll-back label. The reference count should
be decreased by 1 to dereference the count, or else in the device
close stage, the queue cannot be released in the FW and the TIS, PD
will be leaked as well.

By calling the mlx5_txq_release() before continue will recover the
reference count to the initial state and solve the leak.

Fixes: 6f356d3840e6 ("net/mlx5: pass DevX object info in Tx queue start")

Signed-off-by: Bing Zhao <bingz@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 drivers/net/mlx5/mlx5_trigger.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5_trigger.c b/drivers/net/mlx5/mlx5_trigger.c
index 90287a1b75..6c6f228afd 100644
--- a/drivers/net/mlx5/mlx5_trigger.c
+++ b/drivers/net/mlx5/mlx5_trigger.c
@@ -61,8 +61,12 @@ mlx5_txq_start(struct rte_eth_dev *dev)
 			struct mlx5_txq_ctrl *txq_ctrl = mlx5_txq_get(dev, i);
 			struct mlx5_txq_data *txq_data = &txq_ctrl->txq;
 
-			if (!txq_ctrl || txq_data->elts_n != cnt)
+			if (!txq_ctrl)
+				continue;
+			if (txq_data->elts_n != cnt) {
+				mlx5_txq_release(dev, i);
 				continue;
+			}
 			if (!txq_ctrl->is_hairpin)
 				txq_alloc_elts(txq_ctrl);
 			MLX5_ASSERT(!txq_ctrl->obj);
-- 
2.34.1

Re: [PATCH] net/mlx5: fix decreasing the reference count of a Tx queue

[Raslan Darawsheh]

Hi,


On 03/07/2025 6:02 PM, Bing Zhao wrote:
> When changing the order of the Tx queues startup, the depth of the
> queue is compared. If not equal to the current big log2 value, next
> queue will be checked and the current one will be skipped for the
> next iteration.
> 
> The mlx5_txq_get() will increase the reference count number, and the
> size check no match is not an error and the startup will continue but
> not fall into the error roll-back label. The reference count should
> be decreased by 1 to dereference the count, or else in the device
> close stage, the queue cannot be released in the FW and the TIS, PD
> will be leaked as well.
> 
> By calling the mlx5_txq_release() before continue will recover the
> reference count to the initial state and solve the leak.
> 
> Fixes: 6f356d3840e6 ("net/mlx5: pass DevX object info in Tx queue start")
> 
> Signed-off-by: Bing Zhao <bingz@nvidia.com>
> Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

Patch applied to next-net-mlx,

Kindest regards
Raslan Darawsheh