net: Introduce ndo_get_port_parent_id()

In preparation for getting rid of switchdev_ops, create a dedicated NDO
operation for getting the port's parent identifier. There are
essentially two classes of drivers that need to implement getting the
port's parent ID which are VF/PF drivers with a built-in switch, and
pure switchdev drivers such as mlxsw, ocelot, dsa etc.

We introduce a helper function: dev_get_port_parent_id() which supports
recursion into the lower devices to obtain the first port's parent ID.

Convert the bridge, core and ipv4 multicast routing code to check for
such ndo_get_port_parent_id() and call the helper function when valid
before falling back to switchdev_port_attr_get(). This will allow us to
convert all relevant drivers in one go instead of having to implement
both switchdev_port_attr_get() and ndo_get_port_parent_id() operations,
then get rid of switchdev_port_attr_get().

Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index ff9fd2bb4ce4..4eace9f1dcf9 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -495,6 +495,7 @@ static ssize_t phys_switch_id_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct net_device *netdev = to_net_dev(dev);
+	const struct net_device_ops *ops = netdev->netdev_ops;
 	ssize_t ret = -EINVAL;
 
 	if (!rtnl_trylock())
@@ -507,7 +508,11 @@ static ssize_t phys_switch_id_show(struct device *dev,
 			.flags = SWITCHDEV_F_NO_RECURSE,
 		};
 
-		ret = switchdev_port_attr_get(netdev, &attr);
+		if (ops->ndo_get_port_parent_id)
+			ret = dev_get_port_parent_id(netdev, &attr.u.ppid,
+						     false);
+		else
+			ret = switchdev_port_attr_get(netdev, &attr);
 		if (!ret)
 			ret = sprintf(buf, "%*phN\n", attr.u.ppid.id_len,
 				      attr.u.ppid.id);