connector: make callback argument type explicit

The connector documentation states that the argument to the callback
function is always a pointer to a struct cn_msg, but rather than encode it
in the API itself, it uses a void pointer everywhere.  This doesn't make
much sense to encode the pointer in documentation as it prevents proper C
type checking from occurring and can easily allow people to use the wrong
pointer type.  So convert the argument type to an explicit struct cn_msg
pointer.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index fd336c5..3f45669 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c
@@ -269,7 +269,8 @@
  *
  * May sleep.
  */
-int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
+int cn_add_callback(struct cb_id *id, char *name,
+		    void (*callback)(struct cn_msg *))
 {
 	int err;
 	struct cn_dev *dev = &cdev;
@@ -351,9 +352,8 @@
  *
  * Used for notification of a request's processing.
  */
-static void cn_callback(void *data)
+static void cn_callback(struct cn_msg *msg)
 {
-	struct cn_msg *msg = data;
 	struct cn_ctl_msg *ctl;
 	struct cn_ctl_entry *ent;
 	u32 size;