dyn PDCH: Add new_lchan argument to bsc_handover_start()

This is useful if the caller already allocated a new lchan, which will be used
to dynamically re-assign lchans.

The old behavior is maintained by passing NULL.

Change-Id: I2b7151f32f0c04c22f294eb5dd3c7d7dfddf35e7

2 files changed, 12 insertions, 8 deletions

diff --git a/openbsc/src/libbsc/handover_decision.c b/openbsc/src/libbsc/handover_decision.c
index 0f07bcac6..8b9217749 100644
--- a/openbsc/src/libbsc/handover_decision.c
+++ b/openbsc/src/libbsc/handover_decision.c
@@ -48,7 +48,7 @@ static int handover_to_arfcn_bsic(struct gsm_lchan *lchan,
 	}
 
 	/* and actually try to handover to that cell */
-	return bsc_handover_start(lchan, new_bts);
+	return bsc_handover_start(lchan, NULL, new_bts);
 }
 
 /* did we get a RXLEV for a given cell in the given report? */
diff --git a/openbsc/src/libbsc/handover_logic.c b/openbsc/src/libbsc/handover_logic.c
index 56b623a69..de8052679 100644
--- a/openbsc/src/libbsc/handover_logic.c
+++ b/openbsc/src/libbsc/handover_logic.c
@@ -87,10 +87,13 @@ static struct bsc_handover *bsc_ho_by_old_lchan(struct gsm_lchan *old_lchan)
 
 /*! \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. */
-int bsc_handover_start(struct gsm_lchan *old_lchan, struct gsm_bts *bts)
+ * decision whether to initiate HO to a specific BTS.
+ *
+ * If new_lchan is NULL, allocate a new lchan. If not NULL, new_lchan must be a
+ * newly allocated lchan passed in by the caller. */
+int bsc_handover_start(struct gsm_lchan *old_lchan, struct gsm_lchan *new_lchan,
+		       struct gsm_bts *new_bts)
 {
-	struct gsm_lchan *new_lchan;
 	struct bsc_handover *ho;
 	static uint8_t ho_ref;
 	int rc;
@@ -101,19 +104,20 @@ int bsc_handover_start(struct gsm_lchan *old_lchan, struct gsm_bts *bts)
 		return -EBUSY;
 
 	DEBUGP(DHO, "(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);
 
-	osmo_counter_inc(bts->network->stats.handover.attempted);
+	osmo_counter_inc(new_bts->network->stats.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);
+	if (!new_lchan)
+		new_lchan = lchan_alloc(new_bts, old_lchan->type, 0);
 	if (!new_lchan) {
 		LOGP(DHO, LOGL_NOTICE, "No free channel\n");
-		osmo_counter_inc(bts->network->stats.handover.no_channel);
+		osmo_counter_inc(new_bts->network->stats.handover.no_channel);
 		return -ENOSPC;
 	}