pespin has uploaded this change for review. (
https://gerrit.osmocom.org/c/osmo-bsc/+/15408
Change subject: bsc_subscr_conn_fsm: Cleanly clear BSSAP conn if associated
channel closed during WAIT_CC
......................................................................
bsc_subscr_conn_fsm: Cleanly clear BSSAP conn if associated channel closed
during WAIT_CC
TTCN3 BSC_Tests.TC_ms_rel_ind_does_not_cause_bssmap_reset seems to
sometimes run into a race condition on the order of messages received by
osmo-bsc comming from MSC and BTS.
Usual (expected) scenario):
BTS->BSC EST IND
BSC->MSC CL3 Info
BSC<-MSC CC
BTS->BSC REL IND
BTS<-BSC DEACT SACCH
BSC->MSC ClearRequest
BSC<-MSC ClearCommand
BSC->MSC ClearComplete
BTS<-BSC RF Chan Release
BTS->BSC RF Chan Release ACK
Sometimes CC message and REL IND message are received swapped (because they
are sent by different components asynchronously in TTCN3).
As a result, osmo-bsc was failing to go into CLEARING state and was
unable to send the ClearRequest because CC was still not received.
So the idea is to stay in WAIT_CC until CC is received, then check if
the lchan was dropped and in that case go into clearing state.
Change-Id: Id1abf5ee44c60925b478123409f26bd29006202b
---
M src/osmo-bsc/bsc_subscr_conn_fsm.c
1 file changed, 24 insertions(+), 8 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/08/15408/1
diff --git a/src/osmo-bsc/bsc_subscr_conn_fsm.c
b/src/osmo-bsc/bsc_subscr_conn_fsm.c
index f8784f9..b5edeb8 100644
--- a/src/osmo-bsc/bsc_subscr_conn_fsm.c
+++ b/src/osmo-bsc/bsc_subscr_conn_fsm.c
@@ -99,6 +99,12 @@
conn->network->T_defs, \
-1)
+static bool gscon_is_active(struct gsm_subscriber_connection *conn)
+{
+ enum gscon_fsm_states st = conn->fi->state;
+ return st == ST_ACTIVE || st == ST_ASSIGNMENT || st == ST_HANDOVER;
+}
+
/* forward MT DTAP from BSSAP side to RSL side */
static inline void submit_dtap(struct gsm_subscriber_connection *conn, struct
msgb *msg)
{
@@ -333,10 +339,19 @@
switch (event) {
case GSCON_EV_A_CONN_CFM:
/* MSC has confirmed the connection, we now change into the
- * active state and wait there for further operations */
- conn_fsm_state_chg(ST_ACTIVE);
- /* if there's user payload, forward it just like EV_MT_DTAP */
- /* FIXME: Question: if there's user payload attached to the CC,
forward it like EV_MT_DTAP? */
+ * active state and wait there for further operations. */
+ if (conn->lchan) {
+ conn_fsm_state_chg(ST_ACTIVE);
+ /* if there's user payload, forward it just like
EV_MT_DTAP */
+ /* FIXME: Question: if there's user payload attached to
the CC, forward it like EV_MT_DTAP? */
+ } else {
+ /* If associated lchan was released while we were
+ * waiting for the confirmed connection, then instead
+ * simply drop the connection */
+ LOGPFSML(fi, LOGL_INFO, "Connection confirmed but lchan
was dropped before, clearing conn\n");
+ osmo_fsm_inst_state_chg(conn->fi, ST_CLEARING, 60, 999);
+ gscon_bssmap_clear(conn,
GSM0808_CAUSE_EQUIPMENT_FAILURE);
+ }
break;
default:
OSMO_ASSERT(false);
@@ -589,7 +604,7 @@
[ST_WAIT_CC] = {
.name = "WAIT_CC",
.in_event_mask = S(GSCON_EV_A_CONN_CFM),
- .out_state_mask = S(ST_ACTIVE),
+ .out_state_mask = S(ST_ACTIVE) | S(ST_CLEARING),
.action = gscon_fsm_wait_cc,
},
[ST_ACTIVE] = {
@@ -651,9 +666,10 @@
lchan_forget_conn(conn->lchan);
conn->lchan = NULL;
}
- if (!conn->lchan) {
- if (conn->fi->state != ST_CLEARING)
- osmo_fsm_inst_state_chg(conn->fi, ST_CLEARING, 60, 999);
+ /* if conn is not active we cannot send bssap. If on WAIT_CC, then let's
+ * wait until CC is received to tear down */
+ if (!conn->lchan && gscon_is_active(conn)) {
+ osmo_fsm_inst_state_chg(conn->fi, ST_CLEARING, 60, 999);
gscon_bssmap_clear(conn, GSM0808_CAUSE_EQUIPMENT_FAILURE);
}
}
--
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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Change-Id: Id1abf5ee44c60925b478123409f26bd29006202b
Gerrit-Change-Number: 15408
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <pes...@sysmocom.de>
Gerrit-MessageType: newchange
