1 files changed, 342 insertions, 94 deletions

diff --git a/src/common/abis.c b/src/common/abis.c
index 84a3a047..5629cf23 100644
--- a/src/common/abis.c
+++ b/src/common/abis.c
@@ -13,7 +13,7 @@
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
+ * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
@@ -38,46 +38,319 @@
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/signal.h>
 #include <osmocom/core/macaddr.h>
+#include <osmocom/core/fsm.h>
 #include <osmocom/abis/abis.h>
 #include <osmocom/abis/e1_input.h>
 #include <osmocom/abis/ipaccess.h>
 #include <osmocom/gsm/ipa.h>
 
+#include <osmo-bts/abis.h>
 #include <osmo-bts/logging.h>
 #include <osmo-bts/gsm_data.h>
 #include <osmo-bts/bts.h>
 #include <osmo-bts/rsl.h>
 #include <osmo-bts/oml.h>
+#include <osmo-bts/abis_osmo.h>
 #include <osmo-bts/bts_model.h>
+#include <osmo-bts/bts_trx.h>
+#include <osmo-bts/bts_shutdown_fsm.h>
 
 static struct gsm_bts *g_bts;
 
-int abis_oml_sendmsg(struct msgb *msg)
+static struct e1inp_line_ops line_ops;
+
+static struct ipaccess_unit bts_dev_info;
+
+#define S(x) (1 << (x))
+#define	OML_RETRY_TIMER	5
+
+enum abis_link_fsm_state {
+	ABIS_LINK_ST_WAIT_RECONNECT, /* OML link has not yet been established */
+	ABIS_LINK_ST_CONNECTING, /* OML link in process of been established */
+	ABIS_LINK_ST_CONNECTED, /* OML link is established, RSL links may be established or not */
+	ABIS_LINK_ST_FAILED, /* There used to be an active OML connection but it became broken */
+};
+
+static const struct value_string abis_link_fsm_event_names[] = {
+	{ ABIS_LINK_EV_SIGN_LINK_OML_UP, "SIGN_LINK_OML_UP", },
+	{ ABIS_LINK_EV_SIGN_LINK_DOWN,   "SIGN_LINK_DOWN" },
+	{ ABIS_LINK_EV_VTY_RM_ADDR,      "VTY_RM_ADDR" },
+	{}
+};
+
+struct abis_link_fsm_priv {
+	struct bsc_oml_host *current_bsc;
+	struct gsm_bts *bts;
+	char *model_name;
+	bool reconnect_to_current_bsc;
+};
+
+static void reset_oml_link(struct gsm_bts *bts)
 {
-	struct gsm_bts *bts = msg->trx->bts;
+	if (bts->oml_link) {
+		struct timespec now;
 
-	if (!bts->oml_link) {
-		llist_add_tail(&msg->list, &bts->oml_queue);
+		e1inp_sign_link_destroy(bts->oml_link);
+
+		/* Log a special notice if the OML connection was dropped relatively quickly. */
+		if (bts->oml_conn_established_timestamp.tv_sec != 0 && clock_gettime(CLOCK_MONOTONIC, &now) == 0 &&
+		    bts->oml_conn_established_timestamp.tv_sec + OSMO_BTS_OML_CONN_EARLY_DISCONNECT >= now.tv_sec) {
+			LOGP(DABIS, LOGL_FATAL, "OML link was closed early within %" PRIu64 " seconds. "
+			     "If this situation persists, please check your BTS and BSC configuration files for errors. "
+			     "A common error is a mismatch between unit_id configuration parameters of BTS and BSC.\n",
+			     (uint64_t) (now.tv_sec - bts->oml_conn_established_timestamp.tv_sec));
+		}
+		bts->oml_link = NULL;
+	}
+	memset(&bts->oml_conn_established_timestamp, 0, sizeof(bts->oml_conn_established_timestamp));
+
+	/* Same for IPAC_PROTO_OSMO on the same ipa connection: */
+	if (bts->osmo_link) {
+		e1inp_sign_link_destroy(bts->osmo_link);
+		bts->osmo_link = NULL;
+	}
+
+}
+
+static int pick_next_bsc(struct osmo_fsm_inst *fi)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+	struct bsc_oml_host *last;
+
+	if (llist_empty(&bts->bsc_oml_hosts)) {
+		LOGPFSML(fi, LOGL_ERROR, "List of BSCs to connect to is empty!\n");
+		return -1;
+	}
+
+	/* Keep current pointer to priv->current_bsc: */
+	if (priv->reconnect_to_current_bsc) {
+		OSMO_ASSERT(priv->current_bsc);
+		priv->reconnect_to_current_bsc = false;
 		return 0;
-	} else {
-		/* osmo-bts uses msg->trx internally, but libosmo-abis uses
-		 * the signalling link at msg->dst */
-		msg->dst = bts->oml_link;
-		return abis_sendmsg(msg);
 	}
+
+	last = (struct bsc_oml_host *)llist_last_entry(&bts->bsc_oml_hosts, struct bsc_oml_host, list);
+
+	if (!priv->current_bsc || priv->current_bsc == last) /* Pick first one (wrap around): */
+		priv->current_bsc = (struct bsc_oml_host *)llist_first_entry(&bts->bsc_oml_hosts, struct bsc_oml_host, list);
+	else
+		priv->current_bsc = (struct bsc_oml_host *)llist_entry(priv->current_bsc->list.next, struct bsc_oml_host, list);
+
+	return 0;
 }
 
-static void drain_oml_queue(struct gsm_bts *bts)
+static void abis_link_connecting_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
 {
-	struct msgb *msg, *msg2;
-
-	llist_for_each_entry_safe(msg, msg2, &bts->oml_queue, list) {
-		/* osmo-bts uses msg->trx internally, but libosmo-abis uses
-		 * the signalling link at msg->dst */
-		llist_del(&msg->list);
-		msg->dst = bts->oml_link;
-		abis_sendmsg(msg);
+	struct e1inp_line *line;
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+
+	if (bts_shutdown_in_progress(bts)) {
+		LOGPFSML(fi, LOGL_NOTICE, "BTS is shutting down, delaying A-bis connection establishment to BSC\n");
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_WAIT_RECONNECT, OML_RETRY_TIMER, 0);
+		return;
+	}
+
+	if (pick_next_bsc(fi) < 0) {
+		LOGPFSML(fi, LOGL_FATAL, "No BSC available, A-bis connection establishment failed\n");
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
+		return;
 	}
+
+	LOGP(DABIS, LOGL_NOTICE, "A-bis connection establishment to BSC (%s) in progress...\n", priv->current_bsc->addr);
+
+	/* patch in various data from VTY and other sources */
+	line_ops.cfg.ipa.addr = priv->current_bsc->addr;
+	osmo_get_macaddr(bts_dev_info.mac_addr, "eth0");
+	bts_dev_info.site_id = bts->ip_access.site_id;
+	bts_dev_info.bts_id = bts->ip_access.bts_id;
+	bts_dev_info.unit_name = priv->model_name;
+	if (bts->description)
+		bts_dev_info.unit_name = bts->description;
+	bts_dev_info.location2 = priv->model_name;
+
+	line = e1inp_line_find(0);
+	if (!line)
+		line = e1inp_line_create(0, "ipa");
+	if (!line) {
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
+		return;
+	}
+	/* Line always comes already with a "ctor" reference, enough to keep it alive forever. */
+
+	e1inp_line_bind_ops(line, &line_ops);
+	/* This will open the OML connection now */
+	if (e1inp_line_update(line) < 0) {
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
+		return;
+	}
+
+	/* The TCP connection to the BSC is now in progress.
+	 * Wait for OML Link UP to transition to CONNECTED. */
+}
+
+static void abis_link_connecting(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+
+	switch (event) {
+	case ABIS_LINK_EV_SIGN_LINK_OML_UP:
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_CONNECTED, 0, 0);
+		break;
+	case ABIS_LINK_EV_SIGN_LINK_DOWN:
+		reset_oml_link(bts);
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_WAIT_RECONNECT, OML_RETRY_TIMER, 0);
+		break;
+	default:
+		OSMO_ASSERT(0);
+	}
+}
+
+static void abis_link_connected_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	bts_link_estab(g_bts);
+}
+
+static void abis_link_connected(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+	struct gsm_bts_trx *trx;
+	OSMO_ASSERT(event == ABIS_LINK_EV_SIGN_LINK_DOWN);
+
+	/* First remove the OML signalling link */
+	reset_oml_link(bts);
+
+	/* Then iterate over the RSL signalling links */
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		if (trx->bb_transc.rsl.link) {
+			e1inp_sign_link_destroy(trx->bb_transc.rsl.link);
+			trx->bb_transc.rsl.link = NULL;
+			if (trx == trx->bts->c0)
+				load_timer_stop(trx->bts);
+		} else {
+			/* If we have no rsl_link yet it may mean that lower
+			 * layers are still establishing the socket (TCP, IPA).
+			 * Let's tell it to stop connection establishment since
+			 * we are shutting down. */
+			struct e1inp_line *line = e1inp_line_find(0);
+			if (line)
+				e1inp_ipa_bts_rsl_close_n(line, trx->nr);
+		}
+		/* Note: Here we could send NM_EV_RSL_DOWN to each
+		 * trx->(bb_transc.)mo.fi, but we are starting shutdown of the
+		 * entire BTS anyway through bts_model_abis_close(), so simply
+		 * let bts_shutdown FSM take care of slowly powering down all
+		 * the TRX. It would make sense to send NM_EV_RSL_DOWN only if a
+		 * RSL link TRX!=C0 was going down, in order to selectively stop
+		 * that TRX only. But libosmo-abis expects us to drop the entire
+		 * line when something goes wrong... */
+	}
+	bts_model_abis_close(bts);
+
+	/* We want to try reconnecting to the current BSC at least once before switching to a new one: */
+	priv->reconnect_to_current_bsc = true;
+	osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_WAIT_RECONNECT, OML_RETRY_TIMER, 0);
+}
+
+static void abis_link_failed_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+
+	/* None of the configured BSCs was reachable or there was an existing
+	 * OML/RSL connection that broke. Initiate BTS process shut down now. */
+	bts_model_abis_close(bts);
+}
+
+static void abis_link_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+
+	OSMO_ASSERT(event == ABIS_LINK_EV_VTY_RM_ADDR);
+
+	if (priv->current_bsc == data) {
+		if (llist_count(&bts->bsc_oml_hosts) <= 1)
+			priv->current_bsc = NULL;
+		else
+			pick_next_bsc(fi);
+	}
+}
+
+int abis_link_fsm_timer_cb(struct osmo_fsm_inst *fi)
+{
+	switch (fi->state) {
+	case ABIS_LINK_ST_WAIT_RECONNECT:
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_CONNECTING, 0, 0);
+		break;
+	default:
+		OSMO_ASSERT(0);
+	}
+	return 0;
+}
+
+
+static struct osmo_fsm_state abis_link_fsm_states[] = {
+	[ABIS_LINK_ST_WAIT_RECONNECT] = {
+		.name = "WAIT_RECONNECT",
+		.out_state_mask =
+			S(ABIS_LINK_ST_CONNECTING),
+	},
+	[ABIS_LINK_ST_CONNECTING] = {
+		.name = "CONNECTING",
+		.in_event_mask =
+			S(ABIS_LINK_EV_SIGN_LINK_OML_UP) |
+			S(ABIS_LINK_EV_SIGN_LINK_DOWN),
+		.out_state_mask =
+			S(ABIS_LINK_ST_WAIT_RECONNECT) |
+			S(ABIS_LINK_ST_CONNECTED) |
+			S(ABIS_LINK_ST_FAILED),
+		.onenter = abis_link_connecting_onenter,
+		.action = abis_link_connecting,
+	},
+	[ABIS_LINK_ST_CONNECTED] = {
+		.name = "CONNECTED",
+		.in_event_mask =
+			S(ABIS_LINK_EV_SIGN_LINK_DOWN),
+		.out_state_mask =
+			S(ABIS_LINK_ST_WAIT_RECONNECT),
+		.onenter = abis_link_connected_onenter,
+		.action = abis_link_connected,
+	},
+	[ABIS_LINK_ST_FAILED] = {
+		.name = "FAILED",
+		.onenter = abis_link_failed_onenter,
+	},
+};
+
+static struct osmo_fsm abis_link_fsm = {
+	.name = "abis_link",
+	.states = abis_link_fsm_states,
+	.num_states = ARRAY_SIZE(abis_link_fsm_states),
+	.log_subsys = DABIS,
+	.event_names = abis_link_fsm_event_names,
+	.allstate_action = abis_link_allstate,
+	.allstate_event_mask = S(ABIS_LINK_EV_VTY_RM_ADDR),
+	.timer_cb = abis_link_fsm_timer_cb,
+};
+
+int abis_oml_sendmsg(struct msgb *msg)
+{
+	struct gsm_bts *bts = msg->trx->bts;
+
+	if (!bts->oml_link) {
+		LOGP(DABIS, LOGL_INFO, "Drop Tx OML msg, OML link is down\n");
+		msgb_free(msg);
+		return 0;
+	}
+
+	/* osmo-bts uses msg->trx internally, but libosmo-abis uses
+	 * the signalling link at msg->dst */
+	msg->dst = bts->oml_link;
+	return abis_sendmsg(msg);
 }
 
 int abis_bts_rsl_sendmsg(struct msgb *msg)
@@ -91,33 +364,37 @@ int abis_bts_rsl_sendmsg(struct msgb *msg)
 
 	/* osmo-bts uses msg->trx internally, but libosmo-abis uses
 	 * the signalling link at msg->dst */
-	msg->dst = msg->trx->rsl_link;
+	msg->dst = msg->trx->bb_transc.rsl.link;
 	return abis_sendmsg(msg);
 }
 
 static struct e1inp_sign_link *sign_link_up(void *unit, struct e1inp_line *line,
 					    enum e1inp_sign_type type)
 {
-	struct e1inp_sign_link *sign_link = NULL;
+	struct e1inp_ts *sign_ts;
 	struct gsm_bts_trx *trx;
 	int trx_nr;
 
 	switch (type) {
 	case E1INP_SIGN_OML:
+		sign_ts = e1inp_line_ipa_oml_ts(line);
 		LOGP(DABIS, LOGL_INFO, "OML Signalling link up\n");
-		e1inp_ts_config_sign(&line->ts[E1INP_SIGN_OML-1], line);
-		sign_link = g_bts->oml_link =
-			e1inp_sign_link_create(&line->ts[E1INP_SIGN_OML-1],
-						E1INP_SIGN_OML, NULL, 255, 0);
+		e1inp_ts_config_sign(sign_ts, line);
+		g_bts->oml_link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_OML,
+							g_bts->c0, IPAC_PROTO_OML, 0);
 		if (clock_gettime(CLOCK_MONOTONIC, &g_bts->oml_conn_established_timestamp) != 0)
 			memset(&g_bts->oml_conn_established_timestamp, 0,
 			       sizeof(g_bts->oml_conn_established_timestamp));
-		drain_oml_queue(g_bts);
-		sign_link->trx = g_bts->c0;
-		bts_link_estab(g_bts);
-		break;
+		g_bts->osmo_link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_OSMO,
+							  g_bts->c0, IPAC_PROTO_OSMO, 0);
+		osmo_fsm_inst_dispatch(g_bts->abis_link_fi, ABIS_LINK_EV_SIGN_LINK_OML_UP, NULL);
+		return g_bts->oml_link;
+
+	case E1INP_SIGN_RSL:
+		/* fall through to default to catch TRXn having type = E1INP_SIGN_RSL + n  */
 	default:
 		trx_nr = type - E1INP_SIGN_RSL;
+		sign_ts = e1inp_line_ipa_rsl_ts(line, trx_nr);
 		LOGP(DABIS, LOGL_INFO, "RSL Signalling link for TRX%d up\n",
 			trx_nr);
 		trx = gsm_bts_trx_num(g_bts, trx_nr);
@@ -126,54 +403,23 @@ static struct e1inp_sign_link *sign_link_up(void *unit, struct e1inp_line *line,
 				trx_nr);
 			break;
 		}
-		e1inp_ts_config_sign(&line->ts[type-1], line);
-		sign_link = trx->rsl_link =
-			e1inp_sign_link_create(&line->ts[type-1],
-						E1INP_SIGN_RSL, NULL, 0, 0);
-		sign_link->trx = trx;
+		e1inp_ts_config_sign(sign_ts, line);
+		trx->bb_transc.rsl.link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_RSL,
+								 trx, trx->bb_transc.rsl.tei, 0);
 		trx_link_estab(trx);
-		break;
+		return trx->bb_transc.rsl.link;
 	}
-
-	return sign_link;
+	return NULL;
 }
 
 static void sign_link_down(struct e1inp_line *line)
 {
-	struct gsm_bts_trx *trx;
-	LOGP(DABIS, LOGL_ERROR, "Signalling link down\n");
-
-	/* First remove the OML signalling link */
-	if (g_bts->oml_link) {
-		struct timespec now;
-
-		e1inp_sign_link_destroy(g_bts->oml_link);
-
-		/* Log a special notice if the OML connection was dropped relatively quickly. */
-		if (g_bts->oml_conn_established_timestamp.tv_sec != 0 && clock_gettime(CLOCK_MONOTONIC, &now) == 0 &&
-		    g_bts->oml_conn_established_timestamp.tv_sec + OSMO_BTS_OML_CONN_EARLY_DISCONNECT >= now.tv_sec) {
-			LOGP(DABIS, LOGL_FATAL, "OML link was closed early within %" PRIu64 " seconds. "
-			"If this situation persists, please check your BTS and BSC configuration files for errors. "
-			"A common error is a mismatch between unit_id configuration parameters of BTS and BSC.\n",
-			(uint64_t)(now.tv_sec - g_bts->oml_conn_established_timestamp.tv_sec));
-		}
-	}
-	g_bts->oml_link = NULL;
-	memset(&g_bts->oml_conn_established_timestamp, 0, sizeof(g_bts->oml_conn_established_timestamp));
-
-	/* Then iterate over the RSL signalling links */
-	llist_for_each_entry(trx, &g_bts->trx_list, list) {
-		if (trx->rsl_link) {
-			e1inp_sign_link_destroy(trx->rsl_link);
-			trx->rsl_link = NULL;
-		}
-	}
-
-	bts_model_abis_close(g_bts);
+	LOGPIL(line, DABIS, LOGL_ERROR, "Signalling link down\n");
+	osmo_fsm_inst_dispatch(g_bts->abis_link_fi, ABIS_LINK_EV_SIGN_LINK_DOWN, NULL);
 }
 
 
-/* callback for incoming mesages from A-bis/IP */
+/* callback for incoming messages from A-bis/IP */
 static int sign_link_cb(struct msgb *msg)
 {
 	struct e1inp_sign_link *link = msg->dst;
@@ -190,6 +436,9 @@ static int sign_link_cb(struct msgb *msg)
 	case E1INP_SIGN_RSL:
 		down_rsl(link->trx, msg);
 		break;
+	case E1INP_SIGN_OSMO:
+		down_osmo(link->trx->bts, msg);
+		break;
 	default:
 		msgb_free(msg);
 		break;
@@ -212,7 +461,7 @@ uint32_t get_signlink_remote_ip(struct e1inp_sign_link *link)
 		return 0;
 	}
 
-	/* we assume that the soket is AF_INET.  As Abis/IP contains
+	/* we assume that the socket is AF_INET.  As Abis/IP contains
 	 * lots of hard-coded IPv4 addresses, this safe */
 	OSMO_ASSERT(sin.sin_family == AF_INET);
 
@@ -235,7 +484,7 @@ static int inp_s_cbfn(unsigned int subsys, unsigned int signal,
 
 
 static struct ipaccess_unit bts_dev_info = {
-	.unit_name	= "sysmoBTS",
+	.unit_name	= "osmo-bts",
 	.equipvers	= "",	/* FIXME: read this from hw */
 	.swversion	= PACKAGE_VERSION,
 	.location1	= "",
@@ -259,37 +508,36 @@ void abis_init(struct gsm_bts *bts)
 {
 	g_bts = bts;
 
-	oml_init(&bts->mo);
-	libosmo_abis_init(NULL);
+	oml_init();
+	libosmo_abis_init(tall_bts_ctx);
 
 	osmo_signal_register_handler(SS_L_INPUT, &inp_s_cbfn, bts);
 }
 
-struct e1inp_line *abis_open(struct gsm_bts *bts, char *dst_host,
-			     char *model_name)
+int abis_open(struct gsm_bts *bts, char *model_name)
 {
-	struct e1inp_line *line;
+	struct abis_link_fsm_priv *abis_link_fsm_priv;
 
-	/* patch in various data from VTY and othe sources */
-	line_ops.cfg.ipa.addr = dst_host;
-	osmo_get_macaddr(bts_dev_info.mac_addr, "eth0");
-	bts_dev_info.site_id = bts->ip_access.site_id;
-	bts_dev_info.bts_id = bts->ip_access.bts_id;
-	bts_dev_info.unit_name = model_name;
-	if (bts->description)
-		bts_dev_info.unit_name = bts->description;
-	bts_dev_info.location2 = model_name;
+	if (llist_empty(&bts->bsc_oml_hosts)) {
+		LOGP(DABIS, LOGL_FATAL, "No BSC configured, cannot start BTS without knowing BSC OML IP\n");
+		return -EINVAL;
+	}
 
-	line = e1inp_line_find(0);
-	if (!line)
-		line = e1inp_line_create(0, "ipa");
-	if (!line)
-		return NULL;
-	e1inp_line_bind_ops(line, &line_ops);
+	bts->abis_link_fi = osmo_fsm_inst_alloc(&abis_link_fsm, bts, NULL, LOGL_DEBUG, "abis_link");
+	OSMO_ASSERT(bts->abis_link_fi);
 
-	/* This will open the OML connection now */
-	if (e1inp_line_update(line) < 0)
-		return NULL;
+	abis_link_fsm_priv = talloc_zero(bts->abis_link_fi, struct abis_link_fsm_priv);
+	OSMO_ASSERT(abis_link_fsm_priv);
+	abis_link_fsm_priv->bts = bts;
+	abis_link_fsm_priv->model_name = model_name;
+	bts->abis_link_fi->priv = abis_link_fsm_priv;
+
+	osmo_fsm_inst_state_chg(bts->abis_link_fi, ABIS_LINK_ST_CONNECTING, 0, 0);
 
-	return line;
+	return 0;
+}
+
+static __attribute__((constructor)) void abis_link_fsm_init(void)
+{
+	OSMO_ASSERT(osmo_fsm_register(&abis_link_fsm) == 0);
 }