libceph: no need to drop con->mutex for ->get_authorizer()

->get_authorizer(), ->verify_authorizer_reply(), ->sign_message() and
->check_message_signature() shouldn't be doing anything with or on the
connection (like closing it or sending messages).

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>

net/ceph/messenger.c

@@ -1393,15 +1393,9 @@ static struct ceph_auth_handshake *get_connect_authorizer(struct ceph_connection
 		return NULL;
 	}
 
-	/* Can't hold the mutex while getting authorizer */
-	mutex_unlock(&con->mutex);
 	auth = con->ops->get_authorizer(con, auth_proto, con->auth_retry);
-	mutex_lock(&con->mutex);
-
 	if (IS_ERR(auth))
 		return auth;
-	if (con->state != CON_STATE_NEGOTIATING)
-		return ERR_PTR(-EAGAIN);
 
 	con->auth_reply_buf = auth->authorizer_reply_buf;
 	con->auth_reply_buf_len = auth->authorizer_reply_buf_len;