Patch "mlxsw: spectrum: Forbid linking to devices that have uppers" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

mlxsw: spectrum: Forbid linking to devices that have uppers

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mlxsw-spectrum-forbid-linking-to-devices-that-have-uppers.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ido Schimmel <[email protected]>
Date: Fri, 1 Sep 2017 10:52:31 +0200
Subject: mlxsw: spectrum: Forbid linking to devices that have uppers

From: Ido Schimmel <[email protected]>

[ Upstream commit 25cc72a33835ed8a6f53180a822cadab855852ac ]

The mlxsw driver relies on NETDEV_CHANGEUPPER events to configure the device in case a port is enslaved to a master netdev such as bridge or bond.

Since the driver ignores events unrelated to its ports and their uppers, it's possible to engineer situations in which the device's data path differs from the kernel's.

One example to such a situation is when a port is enslaved to a bond that is already enslaved to a bridge. When the bond was enslaved the driver ignored the event - as the bond wasn't one of its uppers - and therefore a bridge port instance isn't created in the device.

Until such configurations are supported forbid them by checking that the upper device doesn't have uppers of its own.

---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c |    6 ++++++
 include/linux/netdevice.h                      |    2 ++
 net/core/dev.c                                 |    3 ++-
 3 files changed, 10 insertions(+), 1 deletion(-)

@@ -4172,6 +4172,8 @@ static int mlxsw_sp_netdevice_port_upper
 			return -EINVAL;
 		if (!info->linking)
 			break;
+		if (netdev_has_any_upper_dev(upper_dev))
+			return -EINVAL;
 		/* HW limitation forbids to put ports to multiple bridges. */
 		if (netif_is_bridge_master(upper_dev) &&
 		    !mlxsw_sp_master_bridge_check(mlxsw_sp, upper_dev))

@@ -4185,6 +4187,10 @@ static int mlxsw_sp_netdevice_port_upper
 		if (netif_is_lag_port(dev) && is_vlan_dev(upper_dev) &&
 		    !netif_is_lag_master(vlan_dev_real_dev(upper_dev)))
 			return -EINVAL;
+		if (!info->linking)
+			break;
+		if (netdev_has_any_upper_dev(upper_dev))
+			return -EINVAL;
 		break;
 	case NETDEV_CHANGEUPPER:
 		upper_dev = info->upper_dev;

@@ -3901,6 +3901,8 @@ struct net_device *netdev_all_upper_get_
 	     updev; \
 	     updev = netdev_all_upper_get_next_dev_rcu(dev, &(iter)))
 
+bool netdev_has_any_upper_dev(struct net_device *dev);
+
 void *netdev_lower_get_next_private(struct net_device *dev,
 				    struct list_head **iter);
 void *netdev_lower_get_next_private_rcu(struct net_device *dev,

@@ -5337,12 +5337,13 @@ EXPORT_SYMBOL(netdev_has_upper_dev);
  * Find out if a device is linked to an upper device and return true in case
  * it is. The caller must hold the RTNL lock.
  */
-static bool netdev_has_any_upper_dev(struct net_device *dev)
+bool netdev_has_any_upper_dev(struct net_device *dev)
 {
 	ASSERT_RTNL();
 
 	return !list_empty(&dev->all_adj_list.upper);
 }
+EXPORT_SYMBOL(netdev_has_any_upper_dev);
 
 /**
  * netdev_master_upper_dev_get - Get master upper device

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/bridge-switchdev-clear-forward-mark-when-transmitting-packet.patch queue-4.9/mlxsw-spectrum-forbid-linking-to-devices-that-have-uppers.patch