sparc64: check if a client is allowed to register for MDESC notifications

Check if a client is supported, by comparing against a whitelist, to
register for notifications from Machine Description (MDESC)
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/mdesc.c

@@ -284,9 +284,26 @@ static struct mdesc_notifier_client *client_list;
 
 void mdesc_register_notifier(struct mdesc_notifier_client *client)
 {
+	bool supported = false;
 	u64 node;
+	int i;
 
 	mutex_lock(&mdesc_mutex);
+
+	/* check to see if the node is supported for registration */
+	for (i = 0; md_node_ops_table[i].name != NULL; i++) {
+		if (strcmp(md_node_ops_table[i].name, client->node_name) == 0) {
+			supported = true;
+			break;
+		}
+	}
+
+	if (!supported) {
+		pr_err("MD: %s node not supported\n", client->node_name);
+		mutex_unlock(&mdesc_mutex);
+		return;
+	}
+
 	client->next = client_list;
 	client_list = client;