abis: Fix line leaked & recreated upon every reconnect

Previous code creating a new line was really a workaroudn to have it
working while previous lines were being stacked internally inside
libosmo-abis.
Let's handle reference counts for the line properly and erase +
re-create it every time.
Recent patches to libosmo-abis fixed a crash happening when refcount
being 0 and destroying the object (object was not removed from a global
llist).

Depends: libosmo-abis Change-Id I1314d6b917ecb622994507475eb894e649a1a2ad
Change-Id: Ic37ae5bf657247e8cce99182c40d9adf890a5e41

2 files changed, 12 insertions, 12 deletions

diff --git a/include/osmo-bts/abis.h b/include/osmo-bts/abis.h
index 40707cd1..d5cf6348 100644
--- a/include/osmo-bts/abis.h
+++ b/include/osmo-bts/abis.h
@@ -8,7 +8,7 @@
 
 enum abis_link_fsm_event {
 	ABIS_LINK_EV_SIGN_LINK_OML_UP,
-	ABIS_LINK_EV_SIGN_LINK_DOWN,
+	ABIS_LINK_EV_SIGN_LINK_DOWN, /* data: struct e1inp_line* of link going down */
 	ABIS_LINK_EV_VTY_RM_ADDR, /* data: struct bsc_oml_host* being removed */
 };
 
diff --git a/src/common/abis.c b/src/common/abis.c
index 93635c2f..b7345766 100644
--- a/src/common/abis.c
+++ b/src/common/abis.c
@@ -81,7 +81,6 @@ struct abis_link_fsm_priv {
 	struct bsc_oml_host *current_bsc;
 	struct gsm_bts *bts;
 	char *model_name;
-	int line_ctr;
 };
 
 static void reset_oml_link(struct gsm_bts *bts)
@@ -156,15 +155,7 @@ static void abis_link_connecting_onenter(struct osmo_fsm_inst *fi, uint32_t prev
 		bts_dev_info.unit_name = bts->description;
 	bts_dev_info.location2 = priv->model_name;
 
-	line = e1inp_line_find(priv->line_ctr);
-	if (line) {
-		e1inp_line_get2(line, __FILE__);	/* We want a new reference for returned line */
-	} else
-		line = e1inp_line_create(priv->line_ctr, "ipa");	/* already comes with a reference */
-
-	/* The abis connection may fail and we may have to try again with a different BSC (if configured). The next
-	 * attempt must happen on a different line. */
-	priv->line_ctr++;
+	line = e1inp_line_create(0, "ipa");	/* already comes with a reference "ctor" */
 
 	if (!line) {
 		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
@@ -186,13 +177,17 @@ static void abis_link_connecting(struct osmo_fsm_inst *fi, uint32_t event, void
 {
 	struct abis_link_fsm_priv *priv = fi->priv;
 	struct gsm_bts *bts = priv->bts;
+	struct e1inp_line *line;
 
 	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:
+		line = (struct e1inp_line *)data;
 		reset_oml_link(bts);
+		/* Drop reference obtained through e1inp_line_create() to get rid of the line object: */
+		e1inp_line_put2(line, "ctor");
 		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_WAIT_RECONNECT, OML_RETRY_TIMER, 0);
 		break;
 	default:
@@ -210,6 +205,7 @@ static void abis_link_connected(struct osmo_fsm_inst *fi, uint32_t event, void *
 	struct abis_link_fsm_priv *priv = fi->priv;
 	struct gsm_bts *bts = priv->bts;
 	struct gsm_bts_trx *trx;
+	struct e1inp_line *line = (struct e1inp_line *)data;
 	OSMO_ASSERT(event == ABIS_LINK_EV_SIGN_LINK_DOWN);
 
 	/* First remove the OML signalling link */
@@ -232,6 +228,10 @@ static void abis_link_connected(struct osmo_fsm_inst *fi, uint32_t event, void *
 		 * that TRX only. But libosmo-abis expects us to drop the entire
 		 * line when something goes wrong... */
 	}
+
+	/* Drop reference obtained through e1inp_line_create() to get rid of the line object: */
+	e1inp_line_put2(line, "ctor");
+
 	bts_model_abis_close(bts);
 	osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_WAIT_RECONNECT, OML_RETRY_TIMER, 0);
 }
@@ -395,7 +395,7 @@ static struct e1inp_sign_link *sign_link_up(void *unit, struct e1inp_line *line,
 static void sign_link_down(struct e1inp_line *line)
 {
 	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);
+	osmo_fsm_inst_dispatch(g_bts->abis_link_fi, ABIS_LINK_EV_SIGN_LINK_DOWN, line);
 }