From: Ido Schimmel <idosch@mellanox.com>
Date: Mon, 25 Dec 2017 09:05:33 +0100
Subject: mlxsw: spectrum: Relax sanity checks during enslavement
Git-commit: 90045fc9c78855bdc625a0ab185d97b72a937613
Patch-mainline: v4.15-rc8
References: networking-stable-18_01_12

Since commit 25cc72a33835 ("mlxsw: spectrum: Forbid linking to devices that
have uppers") the driver forbids enslavement to netdevs that already
have uppers of their own, as this can result in various ordering
problems.

This requirement proved to be too strict for some users who need to be
able to enslave ports to a bridge that already has uppers. In this case,
we can allow the enslavement if the bridge is already known to us, as
any configuration performed on top of the bridge was already reflected
to the device.

[js] backport to 4.12 -- no mlxsw_sp_bridge_device_is_offloaded yet

Fixes: 25cc72a33835 ("mlxsw: spectrum: Forbid linking to devices that have uppers")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Alexander Petrovskiy <alexpe@mellanox.com>
Tested-by: Alexander Petrovskiy <alexpe@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -4157,7 +4157,9 @@ static int mlxsw_sp_netdevice_port_upper
 			return -EINVAL;
 		if (!info->linking)
 			break;
-		if (netdev_has_any_upper_dev(upper_dev))
+		if (netdev_has_any_upper_dev(upper_dev) &&
+		    (!netif_is_bridge_master(upper_dev) ||
+		     mlxsw_sp->master_bridge.dev != upper_dev))
 			return -EINVAL;
 		/* HW limitation forbids to put ports to multiple bridges. */
 		if (netif_is_bridge_master(upper_dev) &&
@@ -4554,6 +4556,7 @@ static int mlxsw_sp_netdevice_vport_even
 					  u16 vid)
 {
 	struct mlxsw_sp_port *mlxsw_sp_port = netdev_priv(dev);
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
 	struct netdev_notifier_changeupper_info *info = ptr;
 	struct mlxsw_sp_port *mlxsw_sp_vport;
 	struct net_device *upper_dev;
@@ -4570,7 +4573,9 @@ static int mlxsw_sp_netdevice_vport_even
 			return -EINVAL;
 		if (!info->linking)
 			break;
-		if (netdev_has_any_upper_dev(upper_dev))
+		if (netdev_has_any_upper_dev(upper_dev) &&
+		    (!netif_is_bridge_master(upper_dev) ||
+		     mlxsw_sp->master_bridge.dev != upper_dev))
 			return -EINVAL;
 		/* We can't have multiple VLAN interfaces configured on
 		 * the same port and being members in the same bridge.