net/mlx5: LAG, replace mlx5_get_dev_index with LAG sequence number

Introduce mlx5_lag_get_dev_seq() which returns a device's sequence
number within the LAG: master is always 0, remaining devices numbered
sequentially. This provides a stable index for peer flow tracking and
vport ordering without depending on native_port_num.

Replace mlx5_get_dev_index() usage in en_tc.c (peer flow array
indexing) and ib_rep.c (vport index ordering) with the new API.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260309093435.1850724-7-tariqt@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/mlx5/ib_rep.c

@@ -3,6 +3,7 @@
  * Copyright (c) 2018 Mellanox Technologies. All rights reserved.
  */
 
+#include <linux/mlx5/lag.h>
 #include <linux/mlx5/vport.h>
 #include "ib_rep.h"
 #include "srq.h"
@@ -134,7 +135,8 @@ mlx5_ib_vport_rep_load(struct mlx5_core_dev *dev, struct mlx5_eswitch_rep *rep)
 				/* Only 1 ib port is the representor for all uplinks */
 					peer_n_ports--;
 
-				if (mlx5_get_dev_index(peer_dev) < mlx5_get_dev_index(dev))
+				if (mlx5_lag_get_dev_seq(peer_dev) <
+				    mlx5_lag_get_dev_seq(dev))
 					vport_index += peer_n_ports;
 			}
 		}

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c

@@ -35,6 +35,7 @@
 #include <net/sch_generic.h>
 #include <net/pkt_cls.h>
 #include <linux/mlx5/fs.h>
+#include <linux/mlx5/lag.h>
 #include <linux/mlx5/device.h>
 #include <linux/rhashtable.h>
 #include <linux/refcount.h>
@@ -2131,7 +2132,7 @@ static void mlx5e_tc_del_fdb_peer_flow(struct mlx5e_tc_flow *flow,
 	mutex_unlock(&esw->offloads.peer_mutex);
 
 	list_for_each_entry_safe(peer_flow, tmp, &flow->peer_flows, peer_flows) {
-		if (peer_index != mlx5_get_dev_index(peer_flow->priv->mdev))
+		if (peer_index != mlx5_lag_get_dev_seq(peer_flow->priv->mdev))
 			continue;
 
 		list_del(&peer_flow->peer_flows);
@@ -2154,7 +2155,7 @@ static void mlx5e_tc_del_fdb_peers_flow(struct mlx5e_tc_flow *flow)
 
 	devcom = flow->priv->mdev->priv.eswitch->devcom;
 	mlx5_devcom_for_each_peer_entry(devcom, peer_esw, pos) {
-		i = mlx5_get_dev_index(peer_esw->dev);
+		i = mlx5_lag_get_dev_seq(peer_esw->dev);
 		mlx5e_tc_del_fdb_peer_flow(flow, i);
 	}
 }
@@ -4584,7 +4585,7 @@ static int mlx5e_tc_add_fdb_peer_flow(struct flow_cls_offload *f,
 	struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
 	struct mlx5_esw_flow_attr *attr = flow->attr->esw_attr;
 	struct mlx5e_tc_flow_parse_attr *parse_attr;
-	int i = mlx5_get_dev_index(peer_esw->dev);
+	int i = mlx5_lag_get_dev_seq(peer_esw->dev);
 	struct mlx5e_rep_priv *peer_urpriv;
 	struct mlx5e_tc_flow *peer_flow;
 	struct mlx5_core_dev *in_mdev;
@@ -5525,7 +5526,7 @@ void mlx5e_tc_clean_fdb_peer_flows(struct mlx5_eswitch *esw)
 	devcom = esw->devcom;
 
 	mlx5_devcom_for_each_peer_entry(devcom, peer_esw, pos) {
-		i = mlx5_get_dev_index(peer_esw->dev);
+		i = mlx5_lag_get_dev_seq(peer_esw->dev);
 		list_for_each_entry_safe(flow, tmp, &esw->offloads.peer_flows[i], peer[i])
 			mlx5e_tc_del_fdb_peers_flow(flow);
 	}

drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c

@@ -35,6 +35,7 @@
 #include <linux/mlx5/driver.h>
 #include <linux/mlx5/eswitch.h>
 #include <linux/mlx5/vport.h>
+#include <linux/mlx5/lag.h>
 #include "lib/mlx5.h"
 #include "lib/devcom.h"
 #include "mlx5_core.h"
@@ -369,6 +370,39 @@ int mlx5_lag_get_dev_index_by_seq(struct mlx5_lag *ldev, int seq)
 	return -ENOENT;
 }
 
+/* Reverse of mlx5_lag_get_dev_index_by_seq: given a device, return its
+ * sequence number in the LAG. Master is always 0, others numbered
+ * sequentially starting from 1.
+ */
+int mlx5_lag_get_dev_seq(struct mlx5_core_dev *dev)
+{
+	struct mlx5_lag *ldev = mlx5_lag_dev(dev);
+	int master_idx, i, num = 1;
+	struct lag_func *pf;
+
+	if (!ldev)
+		return -ENOENT;
+
+	master_idx = mlx5_lag_get_master_idx(ldev);
+	if (master_idx < 0)
+		return -ENOENT;
+
+	pf = mlx5_lag_pf(ldev, master_idx);
+	if (pf && pf->dev == dev)
+		return 0;
+
+	mlx5_ldev_for_each(i, 0, ldev) {
+		if (i == master_idx)
+			continue;
+		pf = mlx5_lag_pf(ldev, i);
+		if (pf->dev == dev)
+			return num;
+		num++;
+	}
+	return -ENOENT;
+}
+EXPORT_SYMBOL(mlx5_lag_get_dev_seq);
+
 /* Devcom events for LAG master marking */
 #define LAG_DEVCOM_PAIR		(0)
 #define LAG_DEVCOM_UNPAIR	(1)

include/linux/mlx5/lag.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/* Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */
+
+#ifndef __MLX5_LAG_API_H__
+#define __MLX5_LAG_API_H__
+
+struct mlx5_core_dev;
+
+int mlx5_lag_get_dev_seq(struct mlx5_core_dev *dev);
+
+#endif /* __MLX5_LAG_API_H__ */