Introduce NM BTS Site Manager FSM

This fixes old behavior mimicing broken behavior in nanoBTS (according to TS 12.21)
where BTS Site Mgr NM object was announced as Enabled despite no OPSTART
was sent by the BSC.
With this new FSM, BTS SiteManager will be announced as Disabled Offline
during OML startup conversation, instead of Enabled.

The new osmo-bsc OML management FSMs use this change in behavior to find
out whether it should use the old broken management states (without
Offline state, as per nanoBTS) or use the new state transitions (which
allow fixing several race conditions).

Change-Id: Iab2d17c45c9642860cd2d5d523c1baae24502243

4 files changed, 198 insertions, 5 deletions

diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index e3a72dc8..458041e3 100644
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -37,6 +37,8 @@ libbts_a_SOURCES = \
 	dtx_dl_amr_fsm.c \
 	scheduler_mframe.c \
 	ta_control.c \
+	nm_common_fsm.c \
+	nm_bts_sm_fsm.c \
 	$(NULL)
 
 libl1sched_a_SOURCES = scheduler.c
diff --git a/src/common/bts.c b/src/common/bts.c
index 8a97b8fa..07706400 100644
--- a/src/common/bts.c
+++ b/src/common/bts.c
@@ -52,6 +52,7 @@
 #include <osmo-bts/dtx_dl_amr_fsm.h>
 #include <osmo-bts/cbch.h>
 #include <osmo-bts/bts_shutdown_fsm.h>
+#include <osmo-bts/nm_common_fsm.h>
 
 #define MIN_QUAL_RACH	 50 /* minimum link quality (in centiBels) for Access Bursts */
 #define MIN_QUAL_NORM	 -5 /* minimum link quality (in centiBels) for Normal Bursts */
@@ -200,6 +201,15 @@ const struct value_string bts_impl_flag_desc[] = {
 	{ 0, NULL }
 };
 
+static int gsm_bts_talloc_destructor(struct gsm_bts *bts)
+{
+	if (bts->site_mgr.mo.fi) {
+		osmo_fsm_inst_free(bts->site_mgr.mo.fi);
+		bts->site_mgr.mo.fi = NULL;
+	}
+	return 0;
+}
+
 struct gsm_bts *gsm_bts_alloc(void *ctx, uint8_t bts_num)
 {
 	struct gsm_bts *bts = talloc_zero(ctx, struct gsm_bts);
@@ -208,6 +218,8 @@ struct gsm_bts *gsm_bts_alloc(void *ctx, uint8_t bts_num)
 	if (!bts)
 		return NULL;
 
+	talloc_set_destructor(bts, gsm_bts_talloc_destructor);
+
 	bts->nr = bts_num;
 	bts->num_trx = 0;
 	INIT_LLIST_HEAD(&bts->trx_list);
@@ -219,10 +231,13 @@ struct gsm_bts *gsm_bts_alloc(void *ctx, uint8_t bts_num)
 					       LOGL_INFO, NULL);
 	osmo_fsm_inst_update_id_f(bts->shutdown_fi, "bts%d", bts->nr);
 
+	bts->site_mgr.mo.fi = osmo_fsm_inst_alloc(&nm_bts_sm_fsm, bts, &bts->site_mgr,
+						  LOGL_INFO, "bts_sm");
+	gsm_mo_init(&bts->site_mgr.mo, bts, NM_OC_SITE_MANAGER,
+		    0xff, 0xff, 0xff);
+
 	gsm_mo_init(&bts->mo, bts, NM_OC_BTS,
 			bts->nr, 0xff, 0xff);
-	gsm_mo_init(&bts->site_mgr.mo, bts, NM_OC_SITE_MANAGER,
-			0xff, 0xff, 0xff);
 
 	for (i = 0; i < ARRAY_SIZE(bts->gprs.nsvc); i++) {
 		bts->gprs.nsvc[i].bts = bts;
@@ -331,7 +346,7 @@ int bts_init(struct gsm_bts *bts)
 	bts->radio_link_timeout.current = bts->radio_link_timeout.oml;
 
 	/* Start with the site manager */
-	oml_mo_state_init(&bts->site_mgr.mo, NM_OPSTATE_ENABLED, NM_AVSTATE_OK);
+	oml_mo_state_init(&bts->site_mgr.mo, NM_OPSTATE_DISABLED, NM_AVSTATE_NOT_INSTALLED);
 
 	/* set BTS to dependency */
 	oml_mo_state_init(&bts->mo, -1, NM_AVSTATE_DEPENDENCY);
@@ -395,8 +410,8 @@ int bts_link_estab(struct gsm_bts *bts)
 
 	LOGP(DSUM, LOGL_INFO, "Main link established, sending NM Status.\n");
 
-	/* BTS and SITE MGR are EANBLED, BTS is DEPENDENCY */
-	oml_tx_state_changed(&bts->site_mgr.mo);
+	/* BTS SITE MGR becomes Offline (tx SW ACT Report), BTS is DEPENDENCY */
+	osmo_fsm_inst_dispatch(bts->site_mgr.mo.fi, NM_EV_SW_ACT, NULL);
 	oml_tx_state_changed(&bts->mo);
 
 	/* those should all be in DEPENDENCY */
diff --git a/src/common/nm_bts_sm_fsm.c b/src/common/nm_bts_sm_fsm.c
new file mode 100644
index 00000000..dedbacbd
--- /dev/null
+++ b/src/common/nm_bts_sm_fsm.c
@@ -0,0 +1,145 @@
+/* NM BTS Site Manager FSM */
+
+/* (C) 2020 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * 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/>.
+ *
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <inttypes.h>
+
+#include <osmocom/core/fsm.h>
+#include <osmocom/core/tdef.h>
+#include <osmocom/gsm/protocol/gsm_12_21.h>
+
+#include <osmo-bts/logging.h>
+#include <osmo-bts/gsm_data.h>
+#include <osmo-bts/bts_model.h>
+#include <osmo-bts/bts.h>
+#include <osmo-bts/rsl.h>
+#include <osmo-bts/nm_common_fsm.h>
+#include <osmo-bts/phy_link.h>
+
+#define X(s) (1 << (s))
+
+#define nm_bts_sm_fsm_state_chg(fi, NEXT_STATE) \
+	osmo_fsm_inst_state_chg(fi, NEXT_STATE, 0, 0)
+
+//////////////////////////
+// FSM STATE ACTIONS
+//////////////////////////
+
+static void st_op_disabled_notinstalled_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	struct gsm_bts_sm *site_mgr = (struct gsm_bts_sm *)fi->priv;
+	site_mgr->mo.opstart_success = false;
+	oml_mo_state_chg(&site_mgr->mo, NM_OPSTATE_DISABLED, NM_AVSTATE_NOT_INSTALLED);
+}
+
+static void st_op_disabled_notinstalled(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct gsm_bts_sm *site_mgr = (struct gsm_bts_sm *)fi->priv;
+
+	switch (event) {
+	case NM_EV_SW_ACT:
+		oml_mo_tx_sw_act_rep(&site_mgr->mo);
+		nm_bts_sm_fsm_state_chg(fi, NM_BTS_SM_ST_OP_DISABLED_OFFLINE);
+		return;
+	default:
+		OSMO_ASSERT(0);
+	}
+}
+
+static void st_op_disabled_offline_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	struct gsm_bts_sm *site_mgr = (struct gsm_bts_sm *)fi->priv;
+	site_mgr->mo.opstart_success = false;
+	oml_mo_state_chg(&site_mgr->mo, NM_OPSTATE_DISABLED, NM_AVSTATE_OFF_LINE);
+}
+
+static void st_op_disabled_offline(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct gsm_bts_sm *site_mgr = (struct gsm_bts_sm *)fi->priv;
+
+	switch (event) {
+	case NM_EV_OPSTART_ACK:
+		site_mgr->mo.opstart_success = true;
+		oml_mo_opstart_ack(&site_mgr->mo);
+		nm_bts_sm_fsm_state_chg(fi, NM_BTS_SM_ST_OP_ENABLED);
+		break; /* check statechg below */
+	case NM_EV_OPSTART_NACK:
+		site_mgr->mo.opstart_success = false;
+		oml_mo_opstart_nack(&site_mgr->mo, (int)(intptr_t)data);
+		return;
+	default:
+		OSMO_ASSERT(0);
+	}
+}
+
+static void st_op_enabled_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	struct gsm_bts_sm *site_mgr = (struct gsm_bts_sm *)fi->priv;
+	oml_mo_state_chg(&site_mgr->mo, NM_OPSTATE_ENABLED, NM_AVSTATE_OK);
+}
+
+static void st_op_enabled(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+}
+
+static struct osmo_fsm_state nm_bts_sm_fsm_states[] = {
+	[NM_BTS_SM_ST_OP_DISABLED_NOTINSTALLED] = {
+		.in_event_mask =
+			X(NM_EV_SW_ACT),
+		.out_state_mask =
+			X(NM_BTS_SM_ST_OP_DISABLED_OFFLINE),
+		.name = "DISABLED_NOTINSTALLED",
+		.onenter = st_op_disabled_notinstalled_on_enter,
+		.action = st_op_disabled_notinstalled,
+	},
+	[NM_BTS_SM_ST_OP_DISABLED_OFFLINE] = {
+		.in_event_mask =
+			X(NM_EV_OPSTART_ACK) |
+			X(NM_EV_OPSTART_NACK),
+		.out_state_mask =
+			X(NM_BTS_SM_ST_OP_ENABLED),
+		.name = "DISABLED_OFFLINE",
+		.onenter = st_op_disabled_offline_on_enter,
+		.action = st_op_disabled_offline,
+	},
+	[NM_BTS_SM_ST_OP_ENABLED] = {
+		.in_event_mask = 0,
+		.out_state_mask = 0,
+		.name = "ENABLED",
+		.onenter = st_op_enabled_on_enter,
+		.action = st_op_enabled,
+	},
+};
+
+struct osmo_fsm nm_bts_sm_fsm = {
+	.name = "NM_BTS_SM_OP",
+	.states = nm_bts_sm_fsm_states,
+	.num_states = ARRAY_SIZE(nm_bts_sm_fsm_states),
+	.event_names = nm_fsm_event_names,
+	.log_subsys = DOML,
+};
+
+static __attribute__((constructor)) void nm_bts_sm_fsm_init(void)
+{
+	OSMO_ASSERT(osmo_fsm_register(&nm_bts_sm_fsm) == 0);
+}
diff --git a/src/common/nm_common_fsm.c b/src/common/nm_common_fsm.c
new file mode 100644
index 00000000..662a7602
--- /dev/null
+++ b/src/common/nm_common_fsm.c
@@ -0,0 +1,31 @@
+/* NM FSM, common bits */
+
+/* (C) 2020 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * 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/>.
+ *
+ */
+#include <osmocom/core/utils.h>
+#include <osmo-bts/nm_common_fsm.h>
+
+
+const struct value_string nm_fsm_event_names[] = {
+	{ NM_EV_SW_ACT, "SW_ACT" },
+	{ NM_EV_OPSTART_ACK, "OPSTART_ACK" },
+	{ NM_EV_OPSTART_NACK, "OPSTART_NACK" },
+	{ 0, NULL }
+};