From 131ab36e3a0455d406062c1549f864d728bc90d6 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Mon, 18 Jan 2016 10:14:54 +0100
Subject: [PATCH] abis: Add a queue of OML messages

When the oml_link is down or not yet established, we currently lost
any OML messages that were scheduled for transmission to the BSC.  Let's
prevent that by keeping a queue of OML messages, which is drained at the
time the OML link comes up again.
---
 include/osmo-bts/gsm_data.h |  1 +
 src/common/abis.c           | 29 +++++++++++++++++++++++++----
 src/common/bts.c            |  1 +
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/include/osmo-bts/gsm_data.h b/include/osmo-bts/gsm_data.h
index 825123802..6a7bca876 100644
--- a/include/osmo-bts/gsm_data.h
+++ b/include/osmo-bts/gsm_data.h
@@ -84,6 +84,7 @@ struct gsm_bts_role_bts {
 
 	struct paging_state *paging_state;
 	char *bsc_oml_host;
+	struct llist_head oml_queue;
 	unsigned int rtp_jitter_buf_ms;
 	struct {
 		uint8_t ciphers;	/* flags A5/1==0x1, A5/2==0x2, A5/3==0x4 */
diff --git a/src/common/abis.c b/src/common/abis.c
index a08f9f3b6..f0c9fc4d7 100644
--- a/src/common/abis.c
+++ b/src/common/abis.c
@@ -54,11 +54,31 @@ static struct gsm_bts *g_bts;
 int abis_oml_sendmsg(struct msgb *msg)
 {
 	struct gsm_bts *bts = msg->trx->bts;
+	struct gsm_bts_role_bts *btsb = bts_role_bts(bts);
 
-	/* 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);
+	if (!bts->oml_link) {
+		llist_add_tail(&msg->list, &btsb->oml_queue);
+		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);
+	}
+}
+
+static void drain_oml_queue(struct gsm_bts *bts)
+{
+	struct gsm_bts_role_bts *btsb = bts_role_bts(bts);
+	struct msgb *msg, *msg2;
+
+	llist_for_each_entry_safe(msg, msg2, &btsb->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);
+	}
 }
 
 int abis_bts_rsl_sendmsg(struct msgb *msg)
@@ -83,6 +103,7 @@ static struct e1inp_sign_link *sign_link_up(void *unit, struct e1inp_line *line,
 		sign_link = g_bts->oml_link =
 			e1inp_sign_link_create(&line->ts[E1INP_SIGN_OML-1],
 						E1INP_SIGN_OML, NULL, 255, 0);
+		drain_oml_queue(g_bts);
 		sign_link->trx = g_bts->c0;
 		bts_link_estab(g_bts);
 		break;
diff --git a/src/common/bts.c b/src/common/bts.c
index 56d260d76..43f4c255c 100644
--- a/src/common/bts.c
+++ b/src/common/bts.c
@@ -164,6 +164,7 @@ int bts_init(struct gsm_bts *bts)
 	}
 
 	INIT_LLIST_HEAD(&btsb->smscb_state.queue);
+	INIT_LLIST_HEAD(&btsb->oml_queue);
 
 	return rc;
 }