Merge branch 'devlink-port-attribute-fixes'

Parav Pandit says:

====================
devlink port attribute fixes

This patchset contains 2 small fixes for devlink port attributes.

Patch summary:
Patch-1 synchronize the devlink port attribute reader
        with net namespace change operation
Patch-2 Ensure to return devlink port's netdevice attributes
        when netdev and devlink instance belong to same net namespace
====================

Link: https://lore.kernel.org/r/20201125091620.6781-1-parav@nvidia.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

net/core/devlink.c

@@ -772,6 +772,8 @@ static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 	if (nla_put_u32(msg, DEVLINK_ATTR_PORT_INDEX, devlink_port->index))
 		goto nla_put_failure;
 
+	/* Hold rtnl lock while accessing port's netdev attributes. */
+	rtnl_lock();
 	spin_lock_bh(&devlink_port->type_lock);
 	if (nla_put_u16(msg, DEVLINK_ATTR_PORT_TYPE, devlink_port->type))
 		goto nla_put_failure_type_locked;
@@ -780,9 +782,10 @@ static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 			devlink_port->desired_type))
 		goto nla_put_failure_type_locked;
 	if (devlink_port->type == DEVLINK_PORT_TYPE_ETH) {
+		struct net *net = devlink_net(devlink_port->devlink);
 		struct net_device *netdev = devlink_port->type_dev;
 
-		if (netdev &&
+		if (netdev && net_eq(net, dev_net(netdev)) &&
 		    (nla_put_u32(msg, DEVLINK_ATTR_PORT_NETDEV_IFINDEX,
 				 netdev->ifindex) ||
 		     nla_put_string(msg, DEVLINK_ATTR_PORT_NETDEV_NAME,
@@ -798,6 +801,7 @@ static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 			goto nla_put_failure_type_locked;
 	}
 	spin_unlock_bh(&devlink_port->type_lock);
+	rtnl_unlock();
 	if (devlink_nl_port_attrs_put(msg, devlink_port))
 		goto nla_put_failure;
 	if (devlink_nl_port_function_attrs_put(msg, devlink_port, extack))
@@ -808,6 +812,7 @@ static int devlink_nl_port_fill(struct sk_buff *msg, struct devlink *devlink,
 
 nla_put_failure_type_locked:
 	spin_unlock_bh(&devlink_port->type_lock);
+	rtnl_unlock();
 nla_put_failure:
 	genlmsg_cancel(msg, hdr);
 	return -EMSGSIZE;