rxrpc: Check that the client conns cache is empty before module removal

Check that the client conns cache is empty before module removal and bug if
not, listing any offending connections that are still present.  Unfortunately,
if there are connections still around, then the transport socket is still
unexpectedly open and active, so we can't just unallocate the connections.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index 82488d6..be437d5 100644
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -92,3 +92,22 @@
 		spin_unlock(&rxrpc_conn_id_lock);
 	}
 }
+
+/*
+ * Destroy the client connection ID tree.
+ */
+void rxrpc_destroy_client_conn_ids(void)
+{
+	struct rxrpc_connection *conn;
+	int id;
+
+	if (!idr_is_empty(&rxrpc_client_conn_ids)) {
+		idr_for_each_entry(&rxrpc_client_conn_ids, conn, id) {
+			pr_err("AF_RXRPC: Leaked client conn %p {%d}\n",
+			       conn, atomic_read(&conn->usage));
+		}
+		BUG();
+	}
+
+	idr_destroy(&rxrpc_client_conn_ids);
+}