libmsc: add timer X36 for delaying LU connections
The idea is to allow re-using the radio channel that was used for
Location Updating to deliver MT SMS over GSUP. This is achieved
by delaying release of a BSSAP/RANAP connection and thus delaying
the release of the radio channel. The delay can be configured
using new timer X36 (default 0 ms), separately for GERAN and UTRAN.
Change-Id: Ic519cab55d65e47b2636124427dab1a1d80fab78
Related: osmo-ttcn3-hacks.git I74fa174ea649adb2112c8e471c0e339a2197a08d
Related: SYS#6913
diff --git a/src/libmsc/msc_a.c b/src/libmsc/msc_a.c
index db1d998..bff5e67 100644
--- a/src/libmsc/msc_a.c
+++ b/src/libmsc/msc_a.c
@@ -155,6 +155,44 @@
}
}
+static void lu_delay_timer_cb(void *data)
+{
+ struct msc_a *msc_a = (struct msc_a *)data;
+ msc_a_put(msc_a, MSC_A_USE_LOCATION_UPDATING);
+}
+
+static void msc_a_put_lu_deferred(struct msc_a *msc_a)
+{
+ unsigned long Tval;
+
+ /* The idea behind timer X36 is to allow re-using the radio channel that was used for
+ * Location Updating to deliver MT SMS over GSUP. This is achieved by delaying
+ * release of a BSSAP/RANAP connection and thus delaying the release of the radio
+ * channel. The delay can be configured separately for GERAN and UTRAN. */
+ switch (msc_a->c.ran->type) {
+ case OSMO_RAT_GERAN_A:
+ Tval = osmo_tdef_get(msc_tdefs_geran, -36, OSMO_TDEF_MS, 0);
+ break;
+ case OSMO_RAT_UTRAN_IU:
+ Tval = osmo_tdef_get(msc_tdefs_utran, -36, OSMO_TDEF_MS, 0);
+ break;
+ default:
+ Tval = 0;
+ break;
+ }
+
+ if (Tval == 0) {
+ /* no delay, put LU token immediately */
+ msc_a_put(msc_a, MSC_A_USE_LOCATION_UPDATING);
+ return;
+ }
+
+ LOG_MSC_A(msc_a, LOGL_INFO, "Keeping LU token for +%lu ms\n", Tval);
+ osmo_timer_schedule(&msc_a->lu_delay_timer,
+ Tval / 1000, /* seconds */
+ Tval % 1000 * 1000); /* microseconds */
+}
+
static void evaluate_acceptance_outcome(struct osmo_fsm_inst *fi, bool conn_accepted)
{
struct msc_a *msc_a = fi->priv;
@@ -180,7 +218,7 @@
osmo_signal_dispatch(SS_SUBSCR, S_SUBSCR_ATTACHED, msc_a_vsub(msc_a));
if (msc_a->complete_layer3_type == COMPLETE_LAYER3_LU)
- msc_a_put(msc_a, MSC_A_USE_LOCATION_UPDATING);
+ msc_a_put_lu_deferred(msc_a);
if (conn_accepted && msc_a->complete_layer3_type == COMPLETE_LAYER3_CM_RE_ESTABLISH_REQ) {
/* Trigger new Assignment to recommence the voice call. A little dance here because normally we verify
@@ -1011,6 +1049,8 @@
/* Invalidate the active conn in VLR subscriber state, if any. */
if (vsub && vsub->msc_conn_ref == msc_a)
vsub->msc_conn_ref = NULL;
+
+ osmo_timer_del(&msc_a->lu_delay_timer);
}
const struct value_string msc_a_fsm_event_names[] = {
@@ -1225,6 +1265,7 @@
osmo_use_count_make_static_entries(&msc_a->use_count, msc_a->use_count_buf, ARRAY_SIZE(msc_a->use_count_buf));
/* Start timeout for first state */
msc_a_state_chg_always(msc_a, MSC_A_ST_VALIDATE_L3);
+ osmo_timer_setup(&msc_a->lu_delay_timer, &lu_delay_timer_cb, msc_a);
return msc_a;
}