Jakub Kicinski [off-list ref] writes:

On Fri, 15 Mar 2019 17:56:07 +0000, Petr Machata wrote:

quoted

diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
index e2091bb2b3a8..cfd9e86ff0ca 100644
--- a/include/net/rtnetlink.h
+++ b/include/net/rtnetlink.h

@@ -110,6 +110,9 @@ struct rtnl_link_ops {
 	int			(*fill_linkxstats)(struct sk_buff *skb,
 						   const struct net_device *dev,
 						   int *prividx, int attr);
+	size_t			(*link_down_reason_get_size)(const struct net_device *dev);
+	int			(*fill_link_down_reason)(struct sk_buff *skb,
+							 const struct net_device *dev);

IMHO the API is a little heavy for returning, what is effectively a u64
value sliced in two..

If a year from now someone wants to add string reason, this API will
just extend naturally to cover that case.

Perhaps the core can just assume the reason will be provided if the NDO
is present?  And the "fill" NDO should probably fill in the reason
structure, rather than getting the skb passed and dealing with netlink
directly.

This copies how other fill APIs are done, in that the responsibility for
filling up the message is deferred to the driver. I think it makes the
API easier to extend: if there ever is richer information available, the
drivers that want to support it just opt in and provide those attributes.

Also perhaps this would be a ethtool-nl candidate (which would
hopefully land soon after the merge window)?

Is this the repository with the patches? I'll take a look.

    https://github.com/mkubecek/ethnl

Thanks,
Petr