devlink: Avoid overwriting port attributes of registered port

Cited commit in fixes tag overwrites the port attributes for the
registered port.

Avoid such error by checking registered flag before setting attributes.

Fixes: 71ad8d5 ("devlink: Replace devlink_port_attrs_set parameters with a struct")
Signed-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20201111034744.35554-1-parav@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/devlink.c

@@ -8254,8 +8254,6 @@ static int __devlink_port_attrs_set(struct devlink_port *devlink_port,
 {
 	struct devlink_port_attrs *attrs = &devlink_port->attrs;
 
-	if (WARN_ON(devlink_port->registered))
-		return -EEXIST;
 	devlink_port->attrs_set = true;
 	attrs->flavour = flavour;
 	if (attrs->switch_id.id_len) {
@@ -8279,6 +8277,8 @@ void devlink_port_attrs_set(struct devlink_port *devlink_port,
 {
 	int ret;
 
+	if (WARN_ON(devlink_port->registered))
+		return;
 	devlink_port->attrs = *attrs;
 	ret = __devlink_port_attrs_set(devlink_port, attrs->flavour);
 	if (ret)
@@ -8301,6 +8301,8 @@ void devlink_port_attrs_pci_pf_set(struct devlink_port *devlink_port, u32 contro
 	struct devlink_port_attrs *attrs = &devlink_port->attrs;
 	int ret;
 
+	if (WARN_ON(devlink_port->registered))
+		return;
 	ret = __devlink_port_attrs_set(devlink_port,
 				       DEVLINK_PORT_FLAVOUR_PCI_PF);
 	if (ret)
@@ -8326,6 +8328,8 @@ void devlink_port_attrs_pci_vf_set(struct devlink_port *devlink_port, u32 contro
 	struct devlink_port_attrs *attrs = &devlink_port->attrs;
 	int ret;
 
+	if (WARN_ON(devlink_port->registered))
+		return;
 	ret = __devlink_port_attrs_set(devlink_port,
 				       DEVLINK_PORT_FLAVOUR_PCI_VF);
 	if (ret)