[PATCH rdma-next] RDMA/mlx5: Add missing error flow in mlx5_ib_set_vport_rep

[Edward Srouji <edwards@nvidia.com>]

From: Shay Drory <shayd@nvidia.com>

mlx5_ib_set_vport_rep() attaches the representor netdev to the IB
device, which takes a netdev reference, and then adds the LAG demux
rule. If mlx5_lag_demux_rule_add() fails, the error is returned
without detaching the netdev. The eswitch does not call unload() for a
representor whose load() failed, so the reference is never dropped and
a later unregister_netdevice() of the representor waits forever while
holding the eswitch representors lock.

Similarly, if ib_device_set_netdev() fails, the rep pointers assigned at
the start of the function are left dangling.

Undo the netdev attach and clear the rep pointers on failure.

Fixes: d6c9b4de8109 ("{net/RDMA}/mlx5: Add LAG demux table API and vport demux rules")
Fixes: 8d159eb2117b ("RDMA/mlx5: Use IB set_netdev and get_netdev functions")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Chiara Meiohas <cmeiohas@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
---
 drivers/infiniband/hw/mlx5/ib_rep.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/ib_rep.c b/drivers/infiniband/hw/mlx5/ib_rep.c
index 65d8767d1830c630f5aa2a2a693110e2c9bc9e48..9cbd27063ba8ff780446d9be2801012492383734 100644
--- a/drivers/infiniband/hw/mlx5/ib_rep.c
+++ b/drivers/infiniband/hw/mlx5/ib_rep.c
@@ -28,7 +28,7 @@ mlx5_ib_set_vport_rep(struct mlx5_core_dev *dev,
 
 	ret = ib_device_set_netdev(&ibdev->ib_dev, ndev, vport_index + 1);
 	if (ret)
-		return ret;
+		goto err_set_netdev;
 
 	/* Only Vports that are not native to the LAG master eswitch need to add
 	 * demux rule.
@@ -36,7 +36,18 @@ mlx5_ib_set_vport_rep(struct mlx5_core_dev *dev,
 	if (mlx5_eswitch_get_total_vports(dev) > vport_index)
 		return 0;
 
-	return mlx5_lag_demux_rule_add(rep_dev, rep->vport, vport_index);
+	ret = mlx5_lag_demux_rule_add(rep_dev, rep->vport, vport_index);
+	if (ret)
+		goto err_demux;
+
+	return 0;
+
+err_demux:
+	ib_device_set_netdev(&ibdev->ib_dev, NULL, vport_index + 1);
+err_set_netdev:
+	rep->rep_data[REP_IB].priv = NULL;
+	ibdev->port[vport_index].rep = NULL;
+	return ret;
 }
 
 static void mlx5_ib_register_peer_vport_reps(struct mlx5_core_dev *mdev);

---
base-commit: 978361dd2ccff357d4fe6aac6ce057d1bfae8312
change-id: 20261015-rep-netdev-leak-93431d272bbb

Best regards,
-- 
Edward Srouji <edwards@nvidia.com>