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Introduce hashtable to lookup bts by <LAC,CI>

This is useful to quickly lookup pagings aiming at a LAC+CI.
Until now, we first looked up in the LAC hashtable and then iterated
over it. However, that means a potential configuration where all BTS
share the same LAC will end up in iterating over 256 bts, which is not
nice.

Change-Id: I47db6c7543e5c6c3b8f0de3ae5ee1b53c2b5f16f
Related: SYS#7062
---
M include/osmocom/bsc/bts.h
M include/osmocom/bsc/gsm_data.h
M src/osmo-bsc/bts.c
M src/osmo-bsc/bts_vty.c
M src/osmo-bsc/osmo_bsc_bssap.c
5 files changed, 18 insertions(+), 2 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/27/38127/1

diff --git a/include/osmocom/bsc/bts.h b/include/osmocom/bsc/bts.h
index 308c5b9..251c161 100644
--- a/include/osmocom/bsc/bts.h
+++ b/include/osmocom/bsc/bts.h
@@ -345,6 +345,8 @@
 	struct hlist_node node_by_nr;
 	/*! Entry in hash table network->bts_by_lac. */
 	struct hlist_node node_by_lac;
+	/*! Entry in hash table network->bts_by_lac_ci. */
+	struct hlist_node node_by_lac_ci;
 	/*! Entry in hash table network->bts_by_ci. */
 	struct hlist_node node_by_ci;
 
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 98414d0..aaaa4be 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -989,6 +989,8 @@
 	struct llist_head bts_rejected;
 	DECLARE_HASHTABLE(bts_by_nr, 10);
 	DECLARE_HASHTABLE(bts_by_lac, 10);
+	DECLARE_HASHTABLE(bts_by_lac_ci, 10);
+	#define LAC_CI_HASHTABLE_KEY(lac, ci) ((((uint32_t)(ci)) << sizeof(lac)) | (uint32_t)(lac))
 	DECLARE_HASHTABLE(bts_by_ci, 10);
 
 	/* BTS-based counters when we can't find the actual BTS
diff --git a/src/osmo-bsc/bts.c b/src/osmo-bsc/bts.c
index 9e31167..c21e5b3 100644
--- a/src/osmo-bsc/bts.c
+++ b/src/osmo-bsc/bts.c
@@ -161,6 +161,7 @@
 	llist_del(&bts->list);
 	hash_del(&bts->node_by_nr);
 	hash_del(&bts->node_by_lac);
+	hash_del(&bts->node_by_lac_ci);
 	hash_del(&bts->node_by_ci);
 
 	paging_destructor(bts);
@@ -209,6 +210,7 @@
 
 	/* Default bts->location_area_code == GSM_LAC_RESERVED_DETACHED, don't add to hashtable: */
 	INIT_HLIST_NODE(&bts->node_by_lac);
+	INIT_HLIST_NODE(&bts->node_by_lac_ci);
 	/* Default CI = 0: */
 	hash_add(net->bts_by_ci, &bts->node_by_ci, bts->cell_identity);
 
diff --git a/src/osmo-bsc/bts_vty.c b/src/osmo-bsc/bts_vty.c
index d439d72..f6ee514 100644
--- a/src/osmo-bsc/bts_vty.c
+++ b/src/osmo-bsc/bts_vty.c
@@ -271,6 +271,11 @@
 	bts->cell_identity = ci;
 	hash_del(&bts->node_by_ci);
 	hash_add(bts->network->bts_by_ci, &bts->node_by_ci, bts->cell_identity);
+	if (bts->location_area_code != GSM_LAC_RESERVED_DETACHED) {
+		hash_del(&bts->node_by_lac_ci);
+		hash_add(bts->network->bts_by_lac_ci, &bts->node_by_lac_ci,
+			 LAC_CI_HASHTABLE_KEY(bts->location_area_code, bts->cell_identity));
+	}
 
 	return CMD_SUCCESS;
 }
@@ -296,7 +301,10 @@
 
 	bts->location_area_code = lac;
 	hash_del(&bts->node_by_lac);
+	hash_del(&bts->node_by_lac_ci);
 	hash_add(bts->network->bts_by_lac, &bts->node_by_lac, bts->location_area_code);
+	hash_add(bts->network->bts_by_lac_ci, &bts->node_by_lac_ci,
+		 LAC_CI_HASHTABLE_KEY(bts->location_area_code, bts->cell_identity));
 
 	return CMD_SUCCESS;
 }
diff --git a/src/osmo-bsc/osmo_bsc_bssap.c b/src/osmo-bsc/osmo_bsc_bssap.c
index 869a31b..6299279 100644
--- a/src/osmo-bsc/osmo_bsc_bssap.c
+++ b/src/osmo-bsc/osmo_bsc_bssap.c
@@ -150,7 +150,8 @@
 		if (!osmo_plmn_cmp(&id->lai.plmn, &bsc_gsmnet->plmn)) {
 			int paged = 0;
 			struct gsm_bts *bts;
-			hash_for_each_possible(bsc_gsmnet->bts_by_lac, bts, node_by_lac, id->lai.lac) {
+			hash_for_each_possible(bsc_gsmnet->bts_by_lac_ci, bts, node_by_lac_ci,
+					       LAC_CI_HASHTABLE_KEY(id->lai.lac, id->cell_identity)) {
 				if (bts->location_area_code != id->lai.lac)
 					continue;
 				if (bts->cell_identity != id->cell_identity)
@@ -179,7 +180,8 @@
 		const struct osmo_lac_and_ci_id *id = &params->cil.id_list[i].lac_and_ci;
 		int paged = 0;
 		struct gsm_bts *bts;
-		hash_for_each_possible(bsc_gsmnet->bts_by_lac, bts, node_by_lac, id->lac) {
+		hash_for_each_possible(bsc_gsmnet->bts_by_lac_ci, bts, node_by_lac_ci,
+				       LAC_CI_HASHTABLE_KEY(id->lac, id->ci)) {
 			if (bts->location_area_code != id->lac)
 				continue;
 			if (bts->cell_identity != id->ci)

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