reinvent connection_for_subscr() and move to libmsc

Implement connection_for_subscr() from a completely different angle: instead of
looking up lchans in bts structs, look up the subscriber in the global list of
gsm_subscriber_connection. static lchan_find() is thus obsoleted.

All callers of connection_for_subscr() live in libmsc, so move to libmsc.

The move and edit are done in a single commit since the old and new
implementation have nothing in common.

Future: osmo-cscn will use this, without bts being present.

Remove implementation of connection_for_subscr() from channel_test.c -- it is
possible that the abort() in there was intended for a regression test, but
actually it seems the implementation was merely added for linking reasons, and
the abort() added to guard against the NULL return value: no comment nor the
commit log indicate that the abort() is test critical; the addition was the
only change in channel_test.c for that commit; at the same time a
connection_for_subscr() call was added in libmsc.

Change-Id: I5e0ba0ecf1726ebd540800f4e98fdfc937c904ff

openbsc/src/libbsc/chan_alloc.c

@@ -481,39 +481,6 @@ int lchan_release(struct gsm_lchan *lchan, int sacch_deact, enum rsl_rel_mode mo
 	return 1;
 }
 
-static struct gsm_lchan* lchan_find(struct gsm_bts *bts, struct gsm_subscriber *subscr) {
-	struct gsm_bts_trx *trx;
-	int ts_no, lchan_no;
-
-	llist_for_each_entry(trx, &bts->trx_list, list) {
-		for (ts_no = 0; ts_no < 8; ++ts_no) {
-			for (lchan_no = 0; lchan_no < TS_MAX_LCHAN; ++lchan_no) {
-				struct gsm_lchan *lchan =
-					&trx->ts[ts_no].lchan[lchan_no];
-				if (lchan->conn && subscr == lchan->conn->subscr)
-					return lchan;
-			}
-		}
-	}
-
-	return NULL;
-}
-
-struct gsm_subscriber_connection *connection_for_subscr(struct gsm_subscriber *subscr)
-{
-	struct gsm_bts *bts;
-	struct gsm_network *net = subscr->group->net;
-	struct gsm_lchan *lchan;
-
-	llist_for_each_entry(bts, &net->bts_list, list) {
-		lchan = lchan_find(bts, subscr);
-		if (lchan)
-			return lchan->conn;
-	}
-
-	return NULL;
-}
-
 void bts_chan_load(struct pchan_load *cl, const struct gsm_bts *bts)
 {
 	struct gsm_bts_trx *trx;

openbsc/src/libmsc/gsm_subscriber.c

@@ -374,3 +374,17 @@ void subscr_expire(struct gsm_subscriber_group *sgrp)
 {
 	db_subscriber_expire(sgrp->net, subscr_expire_callback);
 }
+
+struct gsm_subscriber_connection *connection_for_subscr(struct gsm_subscriber *subscr)
+{
+	/* FIXME: replace this with a backpointer in gsm_subscriber? */
+	struct gsm_network *net = subscr->group->net;
+	struct gsm_subscriber_connection *conn;
+
+	llist_for_each_entry(conn, &net->subscr_conns, entry) {
+		if (conn->subscr == subscr)
+			return conn;
+	}
+
+	return NULL;
+}

openbsc/tests/channel/channel_test.c

@@ -138,8 +138,6 @@ void gsm_net_update_ctype(struct gsm_network *network) {}
 void gsm48_secure_channel() {}
 void paging_request_stop() {}
 void vty_out() {}
-void* connection_for_subscr(void) { abort(); return NULL; }
-
 
 struct tlv_definition nm_att_tlvdef;