[PATCH] osmo-bsc[master]: abis_rsl: properly handle RSL Release Ind from MS

[Neels Hofmeyr]

Review at  https://gerrit.osmocom.org/7221

abis_rsl: properly handle RSL Release Ind from MS

If we receive a Release Ind from the MS, we so far just drop it on the floor,
assuming that some other part of the BSC code invoked something that it is
already taking care of -- which is of course not the case.

If we receive a Release Ind for an lchan that is not in state LCHAN_S_REL_REQ,
signal the MSC with a Clear Request which will lead to a graceful teardown of
the entire connection.

If there should be no conn, immediately invoke the channel release and ignore
BSSAP.

Related: ttcn3 test TC_chan_rel_rll_rel_ind(),
         see I737be141b69a250eb6eb38007f8042981c1a31cf (osmo-ttcn3-hacks)
Change-Id: I0f8c9c4e6b6850b15c70250fd3f88bdf75f9accf
---
M src/libbsc/abis_rsl.c
M src/osmo-bsc/osmo_bsc_api.c
2 files changed, 29 insertions(+), 6 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/21/7221/1

diff --git a/src/libbsc/abis_rsl.c b/src/libbsc/abis_rsl.c
index 7400f89..9ec4f2d 100644
--- a/src/libbsc/abis_rsl.c
+++ b/src/libbsc/abis_rsl.c
@@ -2125,13 +2125,33 @@
 	int sapi;
 	struct gsm_bts *bts;
 
-	/*
-	 * Maybe only one link/SAPI was releasd or the error handling
-	 * was activated. Just return now and let the other code handle
-	 * it.
-	 */
-	if (lchan->state != LCHAN_S_REL_REQ)
+	if (lchan->state == LCHAN_S_NONE) {
+		LOGP(DRSL, LOGL_ERROR, "%s Release requested for an unused lchan\n",
+		     gsm_lchan_name(lchan));
 		return;
+	}
+
+	if (lchan->state != LCHAN_S_REL_REQ) {
+		/* The MS asked us to release. */
+		struct bsc_api *bsc_api = lchan->ts->trx->bts->network->bsc_api;
+		if (!bsc_api || !bsc_api->clear_request) {
+			LOGP(DRSL, LOGL_ERROR, "%s FATAL: no bsc_api to dispatch Clear Request\n",
+			     gsm_lchan_name(lchan));
+			return;
+		}
+		rsl_lchan_set_state(lchan, LCHAN_S_REL_REQ);
+
+		if (!lchan->conn) {
+			/* No conn exists, release the lchan right away */
+			lchan->state = LCHAN_S_REL_REQ;
+			rsl_rf_chan_release(lchan, 0, SACCH_NONE);
+			return;
+		}
+
+		/* Kick off a BSSAP Clear Request followed by a full teardown via MSC. */
+		bsc_api->clear_request(lchan->conn, 0);
+		return;
+	}
 
 	for (sapi = 0; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
 		if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
diff --git a/src/osmo-bsc/osmo_bsc_api.c b/src/osmo-bsc/osmo_bsc_api.c
index 75dae12..b87711d 100644
--- a/src/osmo-bsc/osmo_bsc_api.c
+++ b/src/osmo-bsc/osmo_bsc_api.c
@@ -449,6 +449,9 @@
 static int bsc_clear_request(struct gsm_subscriber_connection *conn, uint32_t cause)
 {
 	struct msgb *resp;
+	if (!conn)
+		return 1;
+
 	return_when_not_connected_val(conn, 1);
 
 	LOGP(DMSC, LOGL_INFO, "Tx MSC CLEAR REQUEST\n");

-- 
To view, visit https://gerrit.osmocom.org/7221
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I0f8c9c4e6b6850b15c70250fd3f88bdf75f9accf
Gerrit-PatchSet: 1
Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>