From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcel Holtmann <marcel@holtmann.org>
Subject: Removing GENL_ID_GENERATE breaks userspace API
Date: Thu, 2 Mar 2017 17:50:38 +0100
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Cc: Network Development <netdev@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
To: Johannes Berg <johannes@sipsolutions.net>,
        "David S. Miller" <davem@davemloft.net>
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Hi Johannes,

you have removed GENL_ID_GENERATE in 4.10, but that is actually breaking userspace API.

commit a07ea4d9941af5a0c6f0be2a71b51ac9c083c5e5
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Mon Oct 24 14:40:02 2016 +0200

    genetlink: no longer support using static family IDs

diff --git a/include/uapi/linux/genetlink.h b/include/uapi/linux/genetlink.h
index 5512c90af7e3..d9b2db4a29c6 100644
--- a/include/uapi/linux/genetlink.h
+++ b/include/uapi/linux/genetlink.h
@@ -26,7 +26,6 @@ struct genlmsghdr {
 /*
  * List of reserved static generic netlink identifiers:
  */
-#define GENL_ID_GENERATE       0
 #define GENL_ID_CTRL           NLMSG_MIN_TYPE

Since the GENL_ID_GENERATE is in include/uapi/ I would have expected that you leave this in. For us, you just broke userspace API with this change.

Regards

Marcel