The third parameter of cn_add_callback accepts functions with void

*()(struct cn_msg *) prototype.  Change cn_ulog_callback to match it by
removing void * and adding struct cn_msg * directly.

It's introduced by commit:
connector: make callback argument type explicit
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/md/dm-log-userspace-transfer.c

@@ -129,9 +129,8 @@ static int fill_pkg(struct cn_msg *msg, struct dm_ulog_request *tfr)
  * This is the connector callback that delivers data
  * that was sent from userspace.
  */
-static void cn_ulog_callback(void *data)
+static void cn_ulog_callback(struct cn_msg *msg)
 {
-	struct cn_msg *msg = (struct cn_msg *)data;
 	struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
 
 	spin_lock(&receiving_list_lock);