[PATCH v12 2/2] IB/mlx5: Fix loopback threshold/accounting in regular path

[Prathamesh Deshpande <prathameshdeshpande7@gmail.com>]

In regular (non-MP) loopback enable/disable paths, threshold logic uses a
hardcoded user_td baseline and does not rollback counters when HW enable
fails.

Use a TD-capability-aware baseline for user_td transitions, and rollback
user_td/qps accounting if mlx5_nic_vport_update_local_lb() fails.

Per review, keep MP helper behavior unchanged.

Fixes: 08aae7860450 ("RDMA/mlx5: Fix vport loopback forcing for MPV device")
Signed-off-by: Prathamesh Deshpande <prathameshdeshpande7@gmail.com>
---
 drivers/infiniband/hw/mlx5/main.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index f6d9841c2bcf..eda578029d28 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -2005,8 +2005,14 @@ static void mlx5_ib_disable_lb_mp(struct mlx5_core_dev *master,
 	lb_state->force_enable = false;
 }
 
+static inline u32 mlx5_ib_lb_td_base(struct mlx5_core_dev *mdev)
+{
+	return MLX5_CAP_GEN(mdev, log_max_transport_domain) ? 1 : 0;
+}
+
 int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 {
+	u32 td_base = mlx5_ib_lb_td_base(dev->mdev);
 	int err = 0;
 
 	if (dev->lb.force_enable)
@@ -2018,11 +2024,18 @@ int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 	if (qp)
 		dev->lb.qps++;
 
-	if (dev->lb.user_td == 2 ||
+	if (dev->lb.user_td == td_base + 1 ||
 	    dev->lb.qps == 1) {
 		if (!dev->lb.enabled) {
 			err = mlx5_nic_vport_update_local_lb(dev->mdev, true);
-			dev->lb.enabled = true;
+			if (err) {
+				if (td)
+					dev->lb.user_td--;
+				if (qp)
+					dev->lb.qps--;
+			} else {
+				dev->lb.enabled = true;
+			}
 		}
 	}
 
@@ -2033,6 +2046,8 @@ int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 
 void mlx5_ib_disable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 {
+	u32 td_base = mlx5_ib_lb_td_base(dev->mdev);
+
 	if (dev->lb.force_enable)
 		return;
 
@@ -2042,7 +2057,7 @@ void mlx5_ib_disable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 	if (qp)
 		dev->lb.qps--;
 
-	if (dev->lb.user_td == 1 &&
+	if (dev->lb.user_td <= td_base &&
 	    dev->lb.qps == 0) {
 		if (dev->lb.enabled) {
 			mlx5_nic_vport_update_local_lb(dev->mdev, false);
-- 
2.43.0