[patch net-next 03/12] net: devlink: introduce devlink_compat_switch_id_get() helper

[Jiri Pirko]

From: Jiri Pirko <j...@mellanox.com>

Introduce devlink_compat_switch_id_get() helper which fills up switch_id
according to passed netdev pointer. Call it directly from
dev_get_port_parent_id() as a fallback when ndo_get_port_parent_id
is not defined for given netdev.

Signed-off-by: Jiri Pirko <j...@mellanox.com>
---
rfc->v1:
- don't take devlink mutexes
- rebase
---
 include/net/devlink.h |  9 +++++++++
 net/core/dev.c        |  8 ++++++--
 net/core/devlink.c    | 19 +++++++++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 0f7968761204..70c7d1ac8344 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -743,6 +743,8 @@ void devlink_compat_running_version(struct net_device *dev,
 int devlink_compat_flash_update(struct net_device *dev, const char *file_name);
 int devlink_compat_phys_port_name_get(struct net_device *dev,
                                      char *name, size_t len);
+int devlink_compat_switch_id_get(struct net_device *dev,
+                                struct netdev_phys_item_id *ppid);
 
 #else
 
@@ -764,6 +766,13 @@ devlink_compat_phys_port_name_get(struct net_device *dev,
        return -EOPNOTSUPP;
 }
 
+static inline int
+devlink_compat_switch_id_get(struct net_device *dev,
+                            struct netdev_phys_item_id *ppid)
+{
+       return -EOPNOTSUPP;
+}
+
 #endif
 
 #endif /* _NET_DEVLINK_H_ */
diff --git a/net/core/dev.c b/net/core/dev.c
index 9823b7713f79..022dc2d86a5b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7905,14 +7905,18 @@ int dev_get_port_parent_id(struct net_device *dev,
        struct netdev_phys_item_id first = { };
        struct net_device *lower_dev;
        struct list_head *iter;
-       int err = -EOPNOTSUPP;
+       int err;
 
        if (ops->ndo_get_port_parent_id)
                return ops->ndo_get_port_parent_id(dev, ppid);
 
-       if (!recurse)
+       err = devlink_compat_switch_id_get(dev, ppid);
+       if (!err || err != -EOPNOTSUPP)
                return err;
 
+       if (!recurse)
+               return -EOPNOTSUPP;
+
        netdev_for_each_lower_dev(dev, lower_dev, iter) {
                err = dev_get_port_parent_id(lower_dev, ppid, recurse);
                if (err)
diff --git a/net/core/devlink.c b/net/core/devlink.c
index eb2424773813..0935b73c2076 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -6511,6 +6511,25 @@ int devlink_compat_phys_port_name_get(struct net_device 
*dev,
        return __devlink_port_phys_port_name_get(devlink_port, name, len);
 }
 
+int devlink_compat_switch_id_get(struct net_device *dev,
+                                struct netdev_phys_item_id *ppid)
+{
+       struct devlink_port *devlink_port;
+
+       /* RTNL mutex is held here which ensures that devlink_port
+        * instance cannot disappear in the middle. No need to take
+        * any devlink lock as only permanent values are accessed.
+        */
+       ASSERT_RTNL();
+       devlink_port = netdev_to_devlink_port(dev);
+       if (!devlink_port || !devlink_port->attrs.switch_port)
+               return -EOPNOTSUPP;
+
+       memcpy(ppid, &devlink_port->attrs.switch_id, sizeof(*ppid));
+
+       return 0;
+}
+
 static int __init devlink_init(void)
 {
        return genl_register_family(&devlink_nl_family);
-- 
2.17.2