netlink: extended ACK reporting

Add the base infrastructure and UAPI for netlink extended ACK
reporting. All "manual" calls to netlink_ack() pass NULL for now and
thus don't get extended ACK reporting.

Big thanks goes to Pablo Neira Ayuso for not only bringing up the
whole topic at netconf (again) but also coming up with the nlattr
passing trick and various other ideas.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c
index fb9d0e2fd148..217f4e3b82f6 100644
--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -238,7 +238,8 @@ static int __sock_diag_cmd(struct sk_buff *skb, struct nlmsghdr *nlh)
         return err;
 }
 
-static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
+                             struct netlink_ext_ack *extack)
 {
         int ret;