Add BTS setup ramping to prevent BSC overloading

Prevent BSC overloading in the event of too many BTS try to connect.
E.g. a network outage between the BSC and BTS.
The BSC will accept incoming OML connection, but will delay sending
any BSC originated messages.

Change-Id: Id56dde6d58f3d0d20352f6c306598d2cccc6345d

5 files changed, 79 insertions, 0 deletions

diff --git a/include/osmocom/bsc/Makefile.am b/include/osmocom/bsc/Makefile.am
index 115c92b3e..53d45adbf 100644
--- a/include/osmocom/bsc/Makefile.am
+++ b/include/osmocom/bsc/Makefile.am
@@ -13,6 +13,7 @@ noinst_HEADERS = \
 	bss.h \
 	bts.h \
 	bts_sm.h \
+	bts_setup_ramp.h \
 	bts_trx.h \
 	bts_ipaccess_nanobts_omlattr.h \
 	chan_alloc.h \
diff --git a/include/osmocom/bsc/bts.h b/include/osmocom/bsc/bts.h
index d71d18fe9..cc4db5aa3 100644
--- a/include/osmocom/bsc/bts.h
+++ b/include/osmocom/bsc/bts.h
@@ -18,6 +18,7 @@
 #include "osmocom/bsc/bts_sm.h"
 #include "osmocom/bsc/abis_om2000.h"
 #include "osmocom/bsc/paging.h"
+#include "osmocom/bsc/bts_setup_ramp.h"
 
 enum bts_counter_id {
 	BTS_CTR_CHREQ_TOTAL,
@@ -666,6 +667,8 @@ struct gsm_bts {
 
 	struct chan_counts chan_counts;
 	struct all_allocated all_allocated;
+
+	struct bts_setup_ramp bts_setup_ramp;
 };
 
 #define GSM_BTS_SI2Q(bts, i)   (struct gsm48_system_information_type_2quater *)((bts)->si_buf[SYSINFO_TYPE_2quater][i])
diff --git a/include/osmocom/bsc/bts_setup_ramp.h b/include/osmocom/bsc/bts_setup_ramp.h
new file mode 100644
index 000000000..0278ee034
--- /dev/null
+++ b/include/osmocom/bsc/bts_setup_ramp.h
@@ -0,0 +1,69 @@
+/* (C) 2022 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * Author: Alexander Couzens <acouzens@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 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/>.
+ *
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/timer.h>
+
+struct gsm_bts;
+struct gsm_network;
+
+enum bts_setup_ramp_state {
+	BTS_SETUP_RAMP_INIT,	/*!< initial state */
+	BTS_SETUP_RAMP_WAIT,	/*!< BTS has to wait, too many BTS configuring */
+	BTS_SETUP_RAMP_READY,	/*!< BTS is allowed to configure */
+};
+
+struct bts_setup_ramp {
+	enum bts_setup_ramp_state state;
+	struct llist_head list;
+};
+
+struct bts_setup_ramp_net {
+	unsigned count; /*!< max count */
+	unsigned step_size; /*!< also the maximum concurrent bts to configure */
+
+	struct llist_head head;
+	struct osmo_timer_list timer;
+	unsigned int step_interval; /*!< in seconds */
+	bool enabled; /*!< enabled by vty */
+	bool active; /*!< if currently active */
+};
+
+void bts_setup_ramp_init_bts(struct gsm_bts *bts);
+void bts_setup_ramp_init_network(struct gsm_network *net);
+
+bool bts_setup_ramp_active(struct gsm_network *net);
+bool bts_setup_ramp_wait(struct gsm_bts *bts);
+void bts_setup_ramp_remove(struct gsm_bts *bts);
+int bts_setup_ramp_unblock_bts(struct gsm_bts *bts);
+
+/* vty related functions */
+void bts_setup_ramp_enable(struct gsm_network *net);
+void bts_setup_ramp_disable(struct gsm_network *net);
+void bts_setup_ramp_set_step_interval(struct gsm_network *net, unsigned int step_interval);
+void bts_setup_ramp_set_step_size(struct gsm_network *net, unsigned int step_size);
+
+const char *bts_setup_ramp_get_state_str(struct gsm_bts *bts);
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 481eae4a0..9300dfa70 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -31,6 +31,7 @@
 #include <osmocom/gsm/protocol/gsm_12_21.h>
 #include <osmocom/gsm/protocol/gsm_03_41.h>
 #include <osmocom/abis/e1_input.h>
+#include <osmocom/bsc/bts_setup_ramp.h>
 #include <osmocom/bsc/meas_rep.h>
 #include <osmocom/bsc/acc.h>
 #include <osmocom/bsc/osmux.h>
@@ -956,6 +957,8 @@ struct gsm_network {
 	/* Don't refuse to start with mutually exclusive codec settings */
 	bool allow_unusable_timeslots;
 
+	struct bts_setup_ramp_net bts_setup_ramp;
+
 	uint8_t nri_bitlen;
 	struct osmo_nri_ranges *null_nri_ranges;
 
diff --git a/include/osmocom/bsc/nm_common_fsm.h b/include/osmocom/bsc/nm_common_fsm.h
index b41d24a60..4c34300a1 100644
--- a/include/osmocom/bsc/nm_common_fsm.h
+++ b/include/osmocom/bsc/nm_common_fsm.h
@@ -38,6 +38,7 @@ enum nm_fsm_events {
 	NM_EV_OPSTART_ACK,
 	NM_EV_OPSTART_NACK,
 	NM_EV_OML_DOWN,
+	NM_EV_SETUP_RAMP_READY, /* BTS setup ramp allow to continue to configure */
 	NM_EV_FORCE_LOCK, /* Only supported by RadioCarrier so far */
 	NM_EV_FEATURE_NEGOTIATED, /* Sent by BTS to NSVC MO */
 	NM_EV_RSL_CONNECT_ACK, /* Sent by BTS to BBTRANSC MO */
@@ -120,3 +121,5 @@ extern struct osmo_fsm nm_gprs_nsvc_fsm;
 void nm_obj_fsm_becomes_enabled_disabled(struct gsm_bts *bts, void *obj,
 					 enum abis_nm_obj_class obj_class,
 					 bool running);
+
+void nm_fsm_dispatch_all_configuring(struct gsm_bts *bts, uint32_t event, void *data);