large refactoring: use FSMs for lchans; add inter-BSC HO

Add FSMs:

- timeslot_fsm: handle dynamic timeslots and OML+RSL availability.
- lchan_fsm: handle an individual lchan activation, RTP stream and release,
  signal the appropriate calling FSMs on success, failure, release.
- mgw_endpoint_fsm: handle one entire endpoint with several CI.
- assignment_fsm: BSSMAP Assignment Request.
- handover_fsm: all of intra, inter-MO and inter-MT handover.

Above FSMs absorb large parts of the gscon FSM. The gscon FSM was surpassing
the maximum amount events (32), and it is more logical to treat assignment,
handover and MGW procedures in separate FSMs.

- Add logging macros for each FSM type:
  - LOG_TS()
  - LOG_LCHAN()
  - LOG_MGWEP(), LOG_CI()
  - LOG_ASSIGNMENT()
  - LOG_HO()
  These log with the osmo_fsm_inst where present.
  New style decision: logging without a final newline char is awkward,
  especially for gsmtap logging and when other logs interleave LOGPC() calls;
  we have various cases where the final \n goes missing, and also this invokes
  the log category checking N times instead of once.
  So I decided to make these macros *always* append a newline, but only if
  there is no final newline yet. I hope that the compiler optimizes the
  strlen() of the constant format strings away. Thus I can log with or without
  typing "\n" and always get an \n termination anyway.

General:

- replace osmo_timers, state enums and program-wide osmo_signal_dispatch()
  with dedicated FSM timeouts, states and events.

- introduce a common way to handle Tnnn timers: gsm_timers.h/.c: struct T_def.
  These can be used (with some macro magic) to define a state's timeout once,
  and not make mistakes for each osmo_fsm_inst_state_chg().

Details:

bsc_subscr_conn_fsm.c:

- move most states of this FSM to lchan_fsm, assignment_fsm, handover_fsm and
  mgw_endpoint_fsm.

- There is exactly one state for an ongoing Assignment, with all details
  handled in conn->assignment.fi. The state relies on the assignment_fsm's
  timeout.

- There is one state for an ongoing Handover; except for an incoming Handover
  from a remote BSS, the gscon remains in ST_INIT until the new lchan and conn
  are both established.

- move bssmap_add_lcls_status() to osmo_bsc_lcls.c

abis_rsl.c:

- move all dynamic timeslot logic away into timeslot_fsm. Only keep plain send/receive functions in
  abis_rsl.c

- reduce some rsl functions to merely send a message, rename to "_tx_".
  - rsl_ipacc_mdcx(): add '_tx_' in the name; move parts that change the lchan state out into the
    lchan_fsm, the lchan->abis_ip.* are now set there prior to invoking this function.

- move all timers and error/release handling away into various FSMs.

- tweak ipa_smod_s_for_lchan() and ipa_rtp_pt_for_lchan() to not require an
  lchan passed, but just mode,type that they require. Rename to
  ipacc_speech_mode*() and ipacc_payload_type().

- add rsl_forward_layer3_info, used for inter-BSC HO MO, to just send the RR
  message received during BSSMAP Handover Command.

- move various logging to LOG_LCHAN() in order to log with the lchan FSM instance.
  One drawback is that the lchan FSM is limited to one logging category, i.e. this moves some logging
  from DRR to DRSL. It might actually make sense to combine those categories.

- lose LOGP...LOGPC logging cascades: they are bad for gsmtap logging and for performance.

- handle_classmark_chg(): change logging, move cm2 len check out of the cm3 condition (I hope that's
  correct).

- gsm48_send_ho_cmd(): split off gsm48_make_ho_cmd() which doesn't send right away, so that during
  inter-bsc HO we can make an RR Handover Command to send via the MSC to the remote BSS.

assignment_fsm.c:

- the Chan Mode Modify in case of re-using the same lchan is not implemented
  yet, because this was also missing in the previous implementation (OS#3357).

osmo_bsc_api.c:

- simplify bsc_mr_config() and move to lchan_fsm.c, the only caller; rename to
  lchan_mr_config(). (bsc_mr_config() used to copy the values to mr_bts_lv
  twice, once by member assignment and then again with a memcpy.)

- During handover, we used to copy the MR config from the old lchan. Since we
  may handover between FR and HR, rather set the MR Config anew every time, so
  that FR rates are always available on FR lchans, and never on HR lchans.

Depends: I03ee7ce840ecfa0b6a33358e7385528aabd4873f (libosmocore),
         I1f2918418c38918c5ac70acaa51a47adfca12b5e (libosmocore)
Change-Id: I82e3f918295daa83274a4cf803f046979f284366

1 files changed, 69 insertions, 383 deletions

diff --git a/src/osmo-bsc/handover_logic.c b/src/osmo-bsc/handover_logic.c
index 0b0a8f448..5725213ef 100644
--- a/src/osmo-bsc/handover_logic.c
+++ b/src/osmo-bsc/handover_logic.c
@@ -33,7 +33,7 @@
 #include <osmocom/bsc/gsm_data.h>
 #include <osmocom/gsm/gsm_utils.h>
 #include <osmocom/bsc/abis_rsl.h>
-#include <osmocom/bsc/chan_alloc.h>
+#include <osmocom/bsc/lchan_select.h>
 #include <osmocom/bsc/signal.h>
 #include <osmocom/core/talloc.h>
 #include <osmocom/bsc/bsc_subscriber.h>
@@ -41,352 +41,88 @@
 #include <osmocom/bsc/handover.h>
 #include <osmocom/bsc/handover_cfg.h>
 #include <osmocom/bsc/bsc_subscr_conn_fsm.h>
+#include <osmocom/bsc/neighbor_ident.h>
+#include <osmocom/bsc/abis_nm.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/gsm/gsm0808_utils.h>
+
+const struct value_string handover_scope_names[] = {
+	{ HO_NO_HANDOVER, "HO-none" },
+	{ HO_INTRA_CELL, "AS" },
+	{ HO_INTRA_BSC, "HO-intraBSC" },
+	{ HO_INTER_BSC_OUT, "HO-interBSC-Out" },
+	{ HO_INTER_BSC_IN, "HO-interBSC-In" },
+	{ HO_SCOPE_ALL, "HO-any" },
+	{}
+};
+
+const struct value_string handover_result_names[] = {
+	{ HO_RESULT_OK, "Complete" },
+	{ HO_RESULT_FAIL_NO_CHANNEL, "Failure (no channel could be allocated)" },
+	{ HO_RESULT_FAIL_RR_HO_FAIL, "Failure (MS sent RR Handover Failure)" },
+	{ HO_RESULT_FAIL_TIMEOUT, "Failure (timeout)" },
+	{ HO_RESULT_CONN_RELEASE, "Connection released" },
+	{ HO_RESULT_ERROR, "Failure" },
+	{}
+};
 
-static LLIST_HEAD(bsc_handovers);
 static LLIST_HEAD(handover_decision_callbacks);
 
-static void handover_free(struct bsc_handover *ho)
-{
-	osmo_timer_del(&ho->T3103);
-	llist_del(&ho->list);
-	talloc_free(ho);
-}
-
-static struct bsc_handover *bsc_ho_by_new_lchan(struct gsm_lchan *new_lchan)
-{
-	struct bsc_handover *ho;
-
-	llist_for_each_entry(ho, &bsc_handovers, list) {
-		if (ho->new_lchan == new_lchan)
-			return ho;
-	}
-
-	return NULL;
-}
-
-static struct bsc_handover *bsc_ho_by_old_lchan(struct gsm_lchan *old_lchan)
-{
-	struct bsc_handover *ho;
-
-	llist_for_each_entry(ho, &bsc_handovers, list) {
-		if (ho->old_lchan == old_lchan)
-			return ho;
-	}
-
-	return NULL;
-}
-
-/*! 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. To not change the lchan type, pass old_lchan->type. */
-int bsc_handover_start(enum hodec_id from_hodec_id, struct gsm_lchan *old_lchan, struct gsm_bts *new_bts,
-		       enum gsm_chan_t new_lchan_type)
-{
-	int rc;
-	struct gsm_subscriber_connection *conn;
-	struct bsc_handover *ho;
-	static uint8_t ho_ref = 0;
-	bool do_assignment;
-
-	OSMO_ASSERT(old_lchan);
-
-	/* don't attempt multiple handovers for the same lchan at
-	 * the same time */
-	if (bsc_ho_by_old_lchan(old_lchan))
-		return -EBUSY;
-
-	conn = old_lchan->conn;
-	if (!conn) {
-		LOGP(DHO, LOGL_ERROR, "Old lchan lacks connection data.\n");
-		return -ENOSPC;
-	}
-
-	if (!new_bts)
-		new_bts = old_lchan->ts->trx->bts;
-	OSMO_ASSERT(new_bts);
-
-	do_assignment = (new_bts == old_lchan->ts->trx->bts);
-
-	ho = talloc_zero(conn, struct bsc_handover);
-	if (!ho) {
-		LOGP(DHO, LOGL_FATAL, "Out of Memory\n");
-		return -ENOMEM;
-	}
-	ho->from_hodec_id = from_hodec_id;
-	ho->old_lchan = old_lchan;
-	ho->new_bts = new_bts;
-	ho->new_lchan_type = new_lchan_type;
-	ho->ho_ref = ho_ref++;
-	ho->inter_cell = !do_assignment;
-	ho->async = true;
-	llist_add(&ho->list, &bsc_handovers);
-
-	conn->ho = ho;
-	rc = osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_HO_START, NULL);
-
-	if (rc < 0) {
-		LOGPHO(ho, LOGL_ERROR, "Failed to trigger handover, conn state does not allow it\n");
-		conn->ho = NULL;
-		talloc_free(ho);
-	}
-	return rc;
-}
-
-/*! Start actual handover. Call bsc_handover_start() instead; The only legal caller is the GSCON FSM in
- * bsc_subscr_conn_fsm.c. */
-int bsc_handover_start_gscon(struct gsm_subscriber_connection *conn)
-{
-	int rc;
-	struct gsm_network *network = conn->network;
-	struct bsc_handover *ho = conn->ho;
-	struct gsm_lchan *old_lchan;
-	struct gsm_lchan *new_lchan;
-
-	if (!ho) {
-		LOGP(DHO, LOGL_ERROR, "%s: Requested to start handover, but conn->ho is NULL\n",
-		     bsc_subscr_name(conn->bsub));
-		return -EINVAL;
-	}
-
-	OSMO_ASSERT(ho->old_lchan && ho->new_bts);
-
-	if (ho->old_lchan->conn != conn) {
-		LOGP(DHO, LOGL_ERROR,
-		     "%s: Requested to start handover, but the lchan does not belong to this conn\n",
-		     bsc_subscr_name(conn->bsub));
-		return -EINVAL;
-	}
-
-	rate_ctr_inc(&network->bsc_ctrs->ctr[BSC_CTR_HANDOVER_ATTEMPTED]);
-
-	ho->new_lchan = lchan_alloc(ho->new_bts, ho->new_lchan_type, 0);
-	if (!ho->new_lchan) {
-		LOGP(DHO, LOGL_NOTICE, "No free channel for %s\n", gsm_lchant_name(ho->new_lchan_type));
-		rate_ctr_inc(&network->bsc_ctrs->ctr[BSC_CTR_HANDOVER_NO_CHANNEL]);
-		return -ENOSPC;
-	}
-
-	LOGPHO(ho, LOGL_INFO, "Triggering %s\n", ho->inter_cell? "Handover" : "Assignment");
-
-	/* copy some parameters from old lchan */
-	old_lchan = ho->old_lchan;
-	new_lchan = ho->new_lchan;
-	memcpy(&new_lchan->encr, &old_lchan->encr, sizeof(new_lchan->encr));
-	if (!ho->inter_cell) {
-		new_lchan->ms_power = old_lchan->ms_power;
-		new_lchan->rqd_ta = old_lchan->rqd_ta;
-	} else {
-		new_lchan->ms_power =
-			ms_pwr_ctl_lvl(ho->new_bts->band, ho->new_bts->ms_max_power);
-		/* FIXME: do we have a better idea of the timing advance? */
-		//new_lchan->rqd_ta = old_lchan->rqd_ta;
-	}
-	new_lchan->bs_power = old_lchan->bs_power;
-	new_lchan->rsl_cmode = old_lchan->rsl_cmode;
-	new_lchan->tch_mode = old_lchan->tch_mode;
-	memcpy(&new_lchan->mr_ms_lv, &old_lchan->mr_ms_lv, sizeof(new_lchan->mr_ms_lv));
-	memcpy(&new_lchan->mr_bts_lv, &old_lchan->mr_bts_lv, sizeof(new_lchan->mr_bts_lv));
-
-	new_lchan->conn = conn;
-
-	rc = rsl_chan_activate_lchan(new_lchan,
-				     ho->async ? RSL_ACT_INTER_ASYNC : RSL_ACT_INTER_SYNC,
-				     ho->ho_ref);
-	if (rc < 0) {
-		LOGPHO(ho, LOGL_INFO, "%s Failure: activate lchan rc = %d\n",
-		       ho->inter_cell? "Handover" : "Assignment", rc);
-		lchan_free(new_lchan);
-		ho->new_lchan = NULL;
-		bsc_clear_handover(conn, 0);
-		return rc;
-	}
-
-	rsl_lchan_set_state(new_lchan, LCHAN_S_ACT_REQ);
-	/* we continue in the SS_LCHAN handler / ho_chan_activ_ack */
-
-	return 0;
-}
-
-/* clear any operation for this connection */
-void bsc_clear_handover(struct gsm_subscriber_connection *conn, int free_lchan)
-{
-	struct bsc_handover *ho = conn->ho;
-
-	if (!ho)
-		return;
-
-	if (ho->new_lchan) {
-		ho->new_lchan->conn = NULL;
-		if (free_lchan)
-			lchan_release(ho->new_lchan, 0, RSL_REL_LOCAL_END);
-		ho->new_lchan = NULL;
-	}
-
-	handover_free(ho);
-	conn->ho = NULL;
-}
-
-/* T3103 expired: Handover has failed without HO COMPLETE or HO FAIL */
-static void ho_T3103_cb(void *_ho)
-{
-	struct bsc_handover *ho = _ho;
-	struct gsm_network *net = ho->new_lchan->ts->trx->bts->network;
-
-	DEBUGP(DHO, "HO T3103 expired\n");
-	rate_ctr_inc(&net->bsc_ctrs->ctr[BSC_CTR_HANDOVER_TIMEOUT]);
-
-	/* Inform the GSCON FSM about the timed out handover */
-	osmo_fsm_inst_dispatch(ho->old_lchan->conn->fi, GSCON_EV_HO_TIMEOUT, NULL);
-
-	bsc_clear_handover(ho->old_lchan->conn, 1);
-}
-
-/* RSL has acknowledged activation of the new lchan */
-static int ho_chan_activ_ack(struct gsm_lchan *new_lchan)
+void handover_decision_callbacks_register(struct handover_decision_callbacks *hdc)
 {
-	struct bsc_handover *ho;
-
-	/* we need to check if this channel activation is related to
-	 * a handover at all (and if, which particular handover) */
-	ho = bsc_ho_by_new_lchan(new_lchan);
-	if (!ho)
-		return -ENODEV;
-
-	LOGPHO(ho, LOGL_INFO, "Channel Activate Ack, send %s COMMAND\n", ho->inter_cell? "HANDOVER" : "ASSIGNMENT");
-
-	/* we can now send the 04.08 HANDOVER COMMAND to the MS
-	 * using the old lchan */
-
-	gsm48_send_ho_cmd(ho->old_lchan, new_lchan, new_lchan->ms_power, ho->ho_ref);
-
-	/* start T3103.  We can continue either with T3103 expiration,
-	 * 04.08 HANDOVER COMPLETE or 04.08 HANDOVER FAIL */
-	osmo_timer_setup(&ho->T3103, ho_T3103_cb, ho);
-	osmo_timer_schedule(&ho->T3103, 10, 0);
-
-	/* create a RTP connection */
-	if (is_ipaccess_bts(new_lchan->ts->trx->bts))
-		rsl_ipacc_crcx(new_lchan);
-
-	return 0;
+	llist_add_tail(&hdc->entry, &handover_decision_callbacks);
 }
 
-/* RSL has not acknowledged activation of the new lchan */
-static int ho_chan_activ_nack(struct gsm_lchan *new_lchan)
+struct handover_decision_callbacks *handover_decision_callbacks_get(int hodec_id)
 {
-	struct bsc_handover *ho;
 	struct handover_decision_callbacks *hdc;
-
-	ho = bsc_ho_by_new_lchan(new_lchan);
-	if (!ho) {
-		/* This lchan is not involved in a handover. */
-		return 0;
-	}
-
-	hdc = handover_decision_callbacks_get(ho->from_hodec_id);
-	if (hdc && hdc->on_ho_chan_activ_nack)
-		hdc->on_ho_chan_activ_nack(ho);
-
-	bsc_clear_handover(new_lchan->conn, 0);
-	return 0;
-}
-
-/* GSM 04.08 HANDOVER COMPLETE has been received on new channel */
-static int ho_gsm48_ho_compl(struct gsm_lchan *new_lchan)
-{
-	struct gsm_network *net;
-	struct bsc_handover *ho;
-
-	ho = bsc_ho_by_new_lchan(new_lchan);
-	if (!ho) {
-		LOGP(DHO, LOGL_ERROR, "unable to find HO record\n");
-		return -ENODEV;
+	llist_for_each_entry(hdc, &handover_decision_callbacks, entry) {
+		if (hdc->hodec_id == hodec_id)
+			return hdc;
 	}
-
-	net = new_lchan->ts->trx->bts->network;
-
-	LOGPHO(ho, LOGL_INFO, "%s Complete\n", ho->inter_cell ? "Handover" : "Assignment");
-
-	rate_ctr_inc(&net->bsc_ctrs->ctr[BSC_CTR_HANDOVER_COMPLETED]);
-
-	osmo_timer_del(&ho->T3103);
-
-	/* Replace the ho lchan with the primary one */
-	if (ho->old_lchan != new_lchan->conn->lchan)
-		LOGPHO(ho, LOGL_ERROR, "Primary lchan changed during handover.\n");
-
-	if (new_lchan->conn->ho != ho)
-		LOGPHO(ho, LOGL_ERROR, "Handover channel changed during this handover.\n");
-
-	new_lchan->conn->lchan = new_lchan;
-	ho->old_lchan->conn = NULL;
-
-	lchan_release(ho->old_lchan, 0, RSL_REL_LOCAL_END);
-
-	handover_free(ho);
-	new_lchan->conn->ho = NULL;
-
-	/* Inform the GSCON FSM that the handover is complete */
-	osmo_fsm_inst_dispatch(new_lchan->conn->fi, GSCON_EV_HO_COMPL, NULL);
-	return 0;
+	return NULL;
 }
 
-/* GSM 04.08 HANDOVER FAIL has been received */
-static int ho_gsm48_ho_fail(struct gsm_lchan *old_lchan)
+static void ho_meas_rep(struct gsm_meas_rep *mr)
 {
-	struct gsm_network *net = old_lchan->ts->trx->bts->network;
-	struct bsc_handover *ho;
 	struct handover_decision_callbacks *hdc;
+	enum hodec_id hodec_id = ho_get_algorithm(mr->lchan->ts->trx->bts->ho);
 
-	ho = bsc_ho_by_old_lchan(old_lchan);
-	if (!ho) {
-		LOGP(DHO, LOGL_ERROR, "unable to find HO record\n");
-		return -ENODEV;
-	}
-
-	hdc = handover_decision_callbacks_get(ho->from_hodec_id);
-	if (hdc && hdc->on_ho_failure)
-		hdc->on_ho_failure(ho);
-
-	rate_ctr_inc(&net->bsc_ctrs->ctr[BSC_CTR_HANDOVER_FAILED]);
-
-	bsc_clear_handover(ho->new_lchan->conn, 1);
-
-	/* Inform the GSCON FSM that the handover failed */
-	osmo_fsm_inst_dispatch(old_lchan->conn->fi, GSCON_EV_HO_FAIL, NULL);
-	return 0;
+	hdc = handover_decision_callbacks_get(hodec_id);
+	if (!hdc || !hdc->on_measurement_report)
+		return;
+	hdc->on_measurement_report(mr);
 }
 
-/* GSM 08.58 HANDOVER DETECT has been received */
-static int ho_rsl_detect(struct gsm_lchan *new_lchan)
+/* Count ongoing handovers within the given BTS.
+ * ho_scopes is an OR'd combination of enum handover_scope values to include in the count. */
+int bts_handover_count(struct gsm_bts *bts, int ho_scopes)
 {
-	struct bsc_handover *ho;
+	struct gsm_bts_trx *trx;
+	int count = 0;
 
-	ho = bsc_ho_by_new_lchan(new_lchan);
-	if (!ho) {
-		LOGP(DHO, LOGL_ERROR, "unable to find HO record\n");
-		return -ENODEV;
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		int i;
+		for (i = 0; i < ARRAY_SIZE(trx->ts); i++) {
+			struct gsm_bts_trx_ts *ts = &trx->ts[i];
+			struct gsm_lchan *lchan;
+
+			/* skip administratively deactivated timeslots */
+			if (!nm_is_running(&ts->mo.nm_state))
+				continue;
+
+			ts_for_each_lchan(lchan, ts) {
+				if (!lchan->conn)
+					continue;
+				if (!lchan->conn->ho.fi)
+					continue;
+				if (lchan->conn->ho.scope & ho_scopes)
+					count++;
+			}
+		}
 	}
 
-	LOGPHO(ho, LOGL_DEBUG, "Handover RACH detected\n");
-
-	/* This is just for logging on the DHO category. The actual MGCP switchover happens in
-	 * osmo_bsc_mgcp.c by receiving the same S_LCHAN_HANDOVER_DETECT signal.
-	 * (Calling mgcp_handover() directly currently breaks linking in utils/...) */
-
-	return 0;
-}
-
-static int ho_meas_rep(struct gsm_meas_rep *mr)
-{
-	struct handover_decision_callbacks *hdc;
-	enum hodec_id hodec_id = ho_get_algorithm(mr->lchan->ts->trx->bts->ho);
-
-	hdc = handover_decision_callbacks_get(hodec_id);
-	if (!hdc || !hdc->on_measurement_report)
-		return 0;
-	hdc->on_measurement_report(mr);
-	return 0;
+	return count;
 }
 
 struct gsm_bts *bts_by_neighbor_ident(const struct gsm_network *net,
@@ -440,73 +176,23 @@ static int ho_logic_sig_cb(unsigned int subsys, unsigned int signal,
 	lchan_data = signal_data;
 	switch (subsys) {
 	case SS_LCHAN:
+		OSMO_ASSERT(lchan_data);
 		lchan = lchan_data->lchan;
+		OSMO_ASSERT(lchan);
+
 		switch (signal) {
-		case S_LCHAN_ACTIVATE_ACK:
-			return ho_chan_activ_ack(lchan);
-		case S_LCHAN_ACTIVATE_NACK:
-			return ho_chan_activ_nack(lchan);
-		case S_LCHAN_HANDOVER_DETECT:
-			return ho_rsl_detect(lchan);
-		case S_LCHAN_HANDOVER_COMPL:
-			return ho_gsm48_ho_compl(lchan);
-		case S_LCHAN_HANDOVER_FAIL:
-			return ho_gsm48_ho_fail(lchan);
 		case S_LCHAN_MEAS_REP:
-			return ho_meas_rep(lchan_data->mr);
+			ho_meas_rep(lchan_data->mr);
+			break;
 		}
-		break;
+
 	default:
 		break;
 	}
-
 	return 0;
 }
 
-/* Return the old lchan or NULL. This is meant for audio handling */
-struct gsm_lchan *bsc_handover_pending(struct gsm_lchan *new_lchan)
-{
-	struct bsc_handover *ho;
-	ho = bsc_ho_by_new_lchan(new_lchan);
-	if (!ho)
-		return NULL;
-	return ho->old_lchan;
-}
-
 static __attribute__((constructor)) void on_dso_load_ho_logic(void)
 {
 	osmo_signal_register_handler(SS_LCHAN, ho_logic_sig_cb, NULL);
 }
-
-/* Count number of currently ongoing handovers
- * inter_cell: if true, count only handovers between two cells. If false, count only handovers within one
- * cell. */
-int bsc_ho_count(struct gsm_bts *bts, bool inter_cell)
-{
-	struct bsc_handover *ho;
-	int count = 0;
-
-	llist_for_each_entry(ho, &bsc_handovers, list) {
-		if (ho->inter_cell != inter_cell)
-			continue;
-		if (ho->new_lchan->ts->trx->bts == bts)
-			count++;
-	}
-
-	return count;
-}
-
-void handover_decision_callbacks_register(struct handover_decision_callbacks *hdc)
-{
-	llist_add_tail(&hdc->entry, &handover_decision_callbacks);
-}
-
-struct handover_decision_callbacks *handover_decision_callbacks_get(int hodec_id)
-{
-	struct handover_decision_callbacks *hdc;
-	llist_for_each_entry(hdc, &handover_decision_callbacks, entry) {
-		if (hdc->hodec_id == hodec_id)
-			return hdc;
-	}
-	return NULL;
-}