From: Nogah Frankel <nogahf@mellanox.com>
Date: Wed, 10 Jan 2018 15:00:07 +0100
Subject: mlxsw: spectrum: qdiscs: Remove qdisc before setting a new one
Patch-mainline: v4.16-rc1
Git-commit: 56202ca4eddf9c3b2cda98095e0f2aa4196ec2ed
References: bsc#1112374

If a qdisc is being replaced by another qdisc of the same type, it can
simply override over its configuration.
However, if it replaces a qdisc of another type, it needs to be removed
before setting the new qdisc.

Signed-off-by: Nogah Frankel <nogahf@mellanox.com>
Reviewed-by: Yuval Mintz <yuvalm@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
@@ -115,6 +115,13 @@ mlxsw_sp_qdisc_replace(struct mlxsw_sp_p
 {
 	int err;
 
+	if (mlxsw_sp_qdisc->ops && mlxsw_sp_qdisc->ops->type != ops->type)
+		/* In case this location contained a different qdisc of the
+		 * same type we can override the old qdisc configuration.
+		 * Otherwise, we need to remove the old qdisc before setting the
+		 * new one.
+		 */
+		mlxsw_sp_qdisc_destroy(mlxsw_sp_port, mlxsw_sp_qdisc);
 	err = ops->check_params(mlxsw_sp_port, mlxsw_sp_qdisc, params);
 	if (err)
 		goto err_bad_param;