static ssize_t phys_switch_id_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct net_device *netdev = to_net_dev(dev);
ssize_t ret = -EINVAL;
if (!rtnl_trylock())
return restart_syscall();
if (dev_isalive(netdev)) {
struct switchdev_attr attr = {
.orig_dev = netdev,
.id = SWITCHDEV_ATTR_ID_PORT_PARENT_ID,
.flags = SWITCHDEV_F_NO_RECURSE,
};
ret = switchdev_port_attr_get(netdev, &attr);
if (!ret)
ret = sprintf(buf, "%*phN\n", attr.u.ppid.id_len,
attr.u.ppid.id);
}
rtnl_unlock();
return ret;
}
/**
* switchdev_port_attr_get - Get port attribute
*
* @dev: port device
* @attr: attribute to get
*/
int switchdev_port_attr_get(struct net_device *dev, struct switchdev_attr *attr)
{
const struct switchdev_ops *ops = dev->switchdev_ops;
struct net_device *lower_dev;
struct list_head *iter;
struct switchdev_attr first = {
.id = SWITCHDEV_ATTR_UNDEFINED
};
int err = -EOPNOTSUPP;
if (ops && ops->switchdev_port_attr_get)
return ops->switchdev_port_attr_get(dev, attr);
if (attr->flags & SWITCHDEV_F_NO_RECURSE)
return err;
/* Switch device port(s) may be stacked under
* bond/team/vlan dev, so recurse down to get attr on
* each port. Return -ENODATA if attr values don't
* compare across ports.
*/
netdev_for_each_lower_dev(dev, lower_dev, iter) {
err = switchdev_port_attr_get(lower_dev, attr);
if (err)
break;
if (first.id == SWITCHDEV_ATTR_UNDEFINED)
first = *attr;
else if (memcmp(&first, attr, sizeof(*attr)))
return -ENODATA;
}