[PATCH] osmo-bsc[master]: HO: add bsc_handover_start_lchan_change()

[Neels Hofmeyr]

Review at  https://gerrit.osmocom.org/6463

HO: add bsc_handover_start_lchan_change()

Upcoming handover_decision_2 will want to be able to handover to a differing
TCH type, hence "add a parameter" to bsc_handover_start() by introducing
bsc_handover_start_lchan_change().

The previous bsc_handover_start() passes the old lchan type to the new function
to provide unchanged behavior. Callers of the current signature are
handover_decision.c (HO algo 1) and bsc_vty.c (manual HO triggering).

Change-Id: I4478ebcaada00897cc38c5a299e07661139ed3c5
---
M include/osmocom/bsc/handover.h
M src/libbsc/handover_logic.c
2 files changed, 19 insertions(+), 9 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/63/6463/1

diff --git a/include/osmocom/bsc/handover.h b/include/osmocom/bsc/handover.h
index a9349ee..f764456 100644
--- a/include/osmocom/bsc/handover.h
+++ b/include/osmocom/bsc/handover.h
@@ -5,6 +5,8 @@
 struct gsm_subscriber_connection;
 
 int bsc_handover_start(struct gsm_lchan *old_lchan, struct gsm_bts *bts);
+int bsc_handover_start_lchan_change(struct gsm_lchan *old_lchan, struct gsm_bts *bts,
+				    enum gsm_chan_t new_lchan_type);
 void bsc_clear_handover(struct gsm_subscriber_connection *conn, int free_lchan);
 struct gsm_lchan *bsc_handover_pending(struct gsm_lchan *new_lchan);
 
diff --git a/src/libbsc/handover_logic.c b/src/libbsc/handover_logic.c
index fd06a54..013377e 100644
--- a/src/libbsc/handover_logic.c
+++ b/src/libbsc/handover_logic.c
@@ -38,6 +38,7 @@
 #include <osmocom/core/talloc.h>
 #include <osmocom/bsc/bsc_subscriber.h>
 #include <osmocom/bsc/gsm_04_08_utils.h>
+#include <osmocom/bsc/handover.h>
 
 struct bsc_handover {
 	struct llist_head list;
@@ -86,10 +87,17 @@
 	return NULL;
 }
 
-/*! \brief Hand over the specified logical channel to the specified new BTS.
- * This is the main entry point for the actual handover algorithm, after the
- * decision whether to initiate HO to a specific BTS. */
+/*! Hand over the specified logical channel to the specified new BTS. */
 int bsc_handover_start(struct gsm_lchan *old_lchan, struct gsm_bts *bts)
+{
+	return bsc_handover_start_lchan_change(old_lchan, bts, old_lchan->type);
+}
+
+/*! Hand over the specified logical channel to the specified new BTS and possibly change the lchan type.
+ * This is the main entry point for the actual handover algorithm, after the decision whether to initiate
+ * HO to a specific BTS. */
+int bsc_handover_start_lchan_change(struct gsm_lchan *old_lchan, struct gsm_bts *new_bts,
+				    enum gsm_chan_t new_lchan_type)
 {
 	struct gsm_lchan *new_lchan;
 	struct bsc_handover *ho;
@@ -103,19 +111,19 @@
 
 	DEBUGP(DHO, "Beginning with handover operation"
 	       "(old_lchan on BTS %u, new BTS %u) ...\n",
-		old_lchan->ts->trx->bts->nr, bts->nr);
+		old_lchan->ts->trx->bts->nr, new_bts->nr);
 
-	rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_HANDOVER_ATTEMPTED]);
+	rate_ctr_inc(&new_bts->network->bsc_ctrs->ctr[BSC_CTR_HANDOVER_ATTEMPTED]);
 
 	if (!old_lchan->conn) {
 		LOGP(DHO, LOGL_ERROR, "Old lchan lacks connection data.\n");
 		return -ENOSPC;
 	}
 
-	new_lchan = lchan_alloc(bts, old_lchan->type, 0);
+	new_lchan = lchan_alloc(new_bts, new_lchan_type, 0);
 	if (!new_lchan) {
-		LOGP(DHO, LOGL_NOTICE, "No free channel\n");
-		rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_HANDOVER_NO_CHANNEL]);
+		LOGP(DHO, LOGL_NOTICE, "No free channel for %s\n", gsm_lchant_name(new_lchan_type));
+		rate_ctr_inc(&new_bts->network->bsc_ctrs->ctr[BSC_CTR_HANDOVER_NO_CHANNEL]);
 		return -ENOSPC;
 	}
 
@@ -128,7 +136,7 @@
 	ho->old_lchan = old_lchan;
 	ho->new_lchan = new_lchan;
 	ho->ho_ref = ho_ref++;
-	if (old_lchan->ts->trx->bts != bts) {
+	if (old_lchan->ts->trx->bts != new_bts) {
 		ho->inter_cell = true;
 		ho->async = true;
 	}

-- 
To view, visit https://gerrit.osmocom.org/6463
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I4478ebcaada00897cc38c5a299e07661139ed3c5
Gerrit-PatchSet: 1
Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>