audit: wake up threads if queue switched from limited to unlimited

If the audit_backlog_limit is changed from a limited value to an
unlimited value (zero) while the queue was overflowed, wake up the
audit_backlog_wait queue to allow those processes to continue.
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>

kernel/audit.c

@@ -523,7 +523,8 @@ static int kauditd_thread(void *dummy)
 		skb = skb_dequeue(&audit_skb_queue);
 
 		if (skb) {
-			if (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit)
+			if (!audit_backlog_limit ||
+			    (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit))
 				wake_up(&audit_backlog_wait);
 			if (audit_pid)
 				kauditd_send_skb(skb);