[PATCH net-next 05/10] devlink: support index-based lookup via bus_name/dev_name handle

[Jiri Pirko <jiri@resnulli.us>]

From: Jiri Pirko <jiri@nvidia.com>

Devlink instances without a backing device use bus_name
"devlink_index" and dev_name set to the decimal index string.
When user space sends this handle, detect the pattern and perform
a direct xarray lookup by index instead of iterating all instances.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
 net/devlink/netlink.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c
index b73cec31089f..127f337489c0 100644
--- a/net/devlink/netlink.c
+++ b/net/devlink/netlink.c
@@ -200,6 +200,15 @@ devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs,
 	busname = nla_data(attrs[DEVLINK_ATTR_BUS_NAME]);
 	devname = nla_data(attrs[DEVLINK_ATTR_DEV_NAME]);
 
+	if (!strcmp(busname, DEVLINK_INDEX_BUS_NAME)) {
+		if (kstrtoul(devname, 10, &index))
+			return ERR_PTR(-EINVAL);
+		devlink = devlinks_xa_lookup_get(net, index);
+		if (!devlink)
+			return ERR_PTR(-ENODEV);
+		goto found;
+	}
+
 	devlinks_xa_for_each_registered_get(net, index, devlink) {
 		if (strcmp(devlink->bus_name, busname) == 0 &&
 		    strcmp(devlink->dev_name, devname) == 0)
-- 
2.51.1