[PATCH] serio: possible race between port removal and kseriod

Input: There is a possibility that serio might get deleted while there
       are outstanding events involving that serio waiting for kseriod
       to process them. Invalidate them so kseriod thread will just
       drop dead events.

drivers/input/serio/serio.c

@@ -87,6 +87,15 @@ static void serio_find_dev(struct serio *serio)
 static DECLARE_WAIT_QUEUE_HEAD(serio_wait);
 static DECLARE_COMPLETION(serio_exited);
 
+static void serio_invalidate_pending_events(struct serio *serio)
+{
+	struct serio_event *event;
+
+	list_for_each_entry(event, &serio_event_list, node)
+		if (event->serio == serio)
+			event->serio = NULL;
+}
+
 void serio_handle_events(void)
 {
 	struct list_head *node, *next;
@@ -95,17 +104,21 @@ void serio_handle_events(void)
 	list_for_each_safe(node, next, &serio_event_list) {
 		event = container_of(node, struct serio_event, node);	
 
+		down(&serio_sem);
+		if (event->serio == NULL)
+			goto event_done;
+
 		switch (event->type) {
 			case SERIO_RESCAN :
-				down(&serio_sem);
 				if (event->serio->dev && event->serio->dev->disconnect)
 					event->serio->dev->disconnect(event->serio);
 				serio_find_dev(event->serio);
-				up(&serio_sem);
 				break;
 			default:
 				break;
 		}
+event_done:
+		up(&serio_sem);
 		list_del_init(node);
 		kfree(event);
 	}
@@ -192,6 +205,7 @@ void serio_unregister_port(struct serio *serio)
  */
 void __serio_unregister_port(struct serio *serio)
 {
+	serio_invalidate_pending_events(serio);
 	list_del_init(&serio->node);
 	if (serio->dev && serio->dev->disconnect)
 		serio->dev->disconnect(serio);