Instead of iterating over all devlink ports add a NDO which
will return the devlink instance from the driver.

Suggested-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Jakub Kicinski <redacted>
---
 include/linux/netdevice.h |  6 ++++
 net/core/devlink.c        | 62 +++++++++++++--------------------------
 2 files changed, 26 insertions(+), 42 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index aab4d9f6613d..eebcef6b8191 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h

@@ -940,6 +940,8 @@ struct dev_ifalias {
 	char ifalias[];
 };
 
+struct devlink;
+
 /*
  * This structure defines the management hooks for network devices.
  * The following hooks can be defined; unless noted otherwise, they are

@@ -1248,6 +1250,9 @@ struct dev_ifalias {
  *	that got dropped are freed/returned via xdp_return_frame().
  *	Returns negative number, means general error invoking ndo, meaning
  *	no frames were xmit'ed and core-caller will free all frames.
+ * struct devlink *(*ndo_get_devlink)(struct net_device *dev);
+ *	Get devlink instance associated with a given netdev.
+ *	Called with a reference on the device only, rtnl_lock is not held.