HO: Add a penalty timer list to the subscriber connection entity

This penalty timer is used to temporarily block cells where handover
or assignment failed or where handover is not allowed. This is usefull
to prevent repeated handover attempts to broken cells or cells that have
limited allowed distance.

Change-Id: I95cb7e3211b2470b773965e7aa94d8eb6c8c1a3a
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 4e07f26..d9dd2d4 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -71,6 +71,13 @@
 	uint8_t classmark3[14]; /* if cm3 gets extended by spec, it will be truncated */
 };
 
+/* penalty timers for handover */
+struct ho_penalty_timer {
+	struct llist_head entry;
+	uint8_t bts;
+	time_t timeout;
+};
+
 /* active radio connection of a mobile subscriber */
 struct gsm_subscriber_connection {
 	/* global linked list of subscriber_connections */
@@ -104,6 +111,9 @@
 	/* Cache DTAP messages during handover/assignment (msgb_enqueue()/msgb_dequeue())*/
 	struct llist_head ho_dtap_cache;
 	unsigned int ho_dtap_cache_len;
+
+	/* penalty timers for handover */
+	struct llist_head ho_penalty_timers;
 };
 
 static inline struct gsm_bts *conn_get_bts(struct gsm_subscriber_connection *conn) {