avoid releasing ues doing s1 handover before TS1relocoverall expiry

srsenb/src/stack/rrc/rrc_ue.cc

@@ -63,11 +63,19 @@ int rrc::ue::init()
 
   // Set timeout to release UE context after RLF detection
   uint32_t deadline_ms = parent->cfg.rlf_release_timer_ms;
+  if (rnti != SRSRAN_MRNTI) {
     auto timer_expire_func = [this](uint32_t tid) { rlf_timer_expired(tid); };
     phy_dl_rlf_timer.set(deadline_ms, timer_expire_func);
     phy_ul_rlf_timer.set(deadline_ms, timer_expire_func);
     rlc_rlf_timer.set(deadline_ms, timer_expire_func);
     parent->logger.info("Setting RLF timer for rnti=0x%x to %dms", rnti, deadline_ms);
+  } else {
+    // in case of M-RNTI do not handle rlf timer expiration
+    auto timer_expire_func = [](uint32_t tid) {};
+    phy_dl_rlf_timer.set(deadline_ms, timer_expire_func);
+    phy_ul_rlf_timer.set(deadline_ms, timer_expire_func);
+    rlc_rlf_timer.set(deadline_ms, timer_expire_func);
+  }
 
   mobility_handler = make_rnti_obj<rrc_mobility>(rnti, this);
   return SRSRAN_SUCCESS;
@@ -94,12 +102,13 @@ void rrc::ue::get_metrics(rrc_ue_metrics_t& ue_metrics) const
 
 void rrc::ue::set_activity()
 {
+  if (rnti == SRSRAN_MRNTI) {
+    return;
+  }
   // re-start activity timer with current timeout value
   activity_timer.run();
-  if (parent) {
   parent->logger.debug("Activity registered for rnti=0x%x (timeout_value=%dms)", rnti, activity_timer.duration());
 }
-}
 
 void rrc::ue::set_radiolink_dl_state(bool crc_res)
 {
@@ -165,14 +174,11 @@ void rrc::ue::set_radiolink_ul_state(bool crc_res)
 
 void rrc::ue::activity_timer_expired(const activity_timeout_type_t type)
 {
-  if (parent) {
   parent->logger.info("Activity timer for rnti=0x%x expired after %d ms", rnti, activity_timer.time_elapsed());
 
   if (parent->s1ap->user_exists(rnti)) {
     if (type == UE_INACTIVITY_TIMEOUT) {
-        if (not parent->s1ap->user_release(rnti, asn1::s1ap::cause_radio_network_opts::user_inactivity)) {
-          parent->rem_user_thread(rnti);
-        }
+      parent->s1ap->user_release(rnti, asn1::s1ap::cause_radio_network_opts::user_inactivity);
       con_release_result = procedure_result_code::activity_timeout;
     } else if (type == MSG3_RX_TIMEOUT) {
       // MSG3 timeout, no need to notify S1AP, just remove UE
@@ -186,11 +192,8 @@ void rrc::ue::activity_timer_expired(const activity_timeout_type_t type)
           "Unhandled reason for activity timer expiration. rnti=0x%x, cause %d", rnti, static_cast<unsigned>(type));
     }
   } else {
-      if (rnti != SRSRAN_MRNTI) {
     parent->rem_user_thread(rnti);
   }
-    }
-  }
 
   state = RRC_STATE_RELEASE_REQUEST;
 }
@@ -211,11 +214,8 @@ void rrc::ue::rlf_timer_expired(uint32_t timeout_id)
   rlc_rlf_timer.stop();
   state = RRC_STATE_RELEASE_REQUEST;
 
-  if (parent->s1ap->user_release(rnti, asn1::s1ap::cause_radio_network_opts::radio_conn_with_ue_lost)) {
+  parent->s1ap->user_release(rnti, asn1::s1ap::cause_radio_network_opts::radio_conn_with_ue_lost);
   con_release_result = procedure_result_code::radio_conn_with_ue_lost;
-  } else if (rnti != SRSRAN_MRNTI) {
-    parent->rem_user(rnti);
-  }
 }
 
 void rrc::ue::max_rlc_retx_reached()
@@ -390,9 +390,7 @@ void rrc::ue::handle_rrc_con_req(rrc_conn_request_s* msg)
       if (user.first != rnti && user.second->has_tmsi && user.second->mmec == mmec && user.second->m_tmsi == m_tmsi) {
         parent->logger.info("RRC connection request: UE context already exists. M-TMSI=%d", m_tmsi);
         user.second->state = RRC_STATE_IDLE; // Set old rnti to IDLE so that enb doesn't send RRC Connection Release
-        if (not parent->s1ap->user_release(user.first, asn1::s1ap::cause_radio_network_opts::radio_conn_with_ue_lost)) {
-          parent->rem_user_thread(user.first);
-        }
+        parent->s1ap->user_release(user.first, asn1::s1ap::cause_radio_network_opts::radio_conn_with_ue_lost);
         break;
       }
     }

srsenb/src/stack/s1ap/s1ap.cc

@@ -414,6 +414,7 @@ bool s1ap::user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_r
   ue* u = users.find_ue_rnti(rnti);
   if (u == nullptr) {
     logger.warning("Released UE with rnti=0x%x not found", rnti);
+    rrc->release_ue(rnti);
     return false;
   }
 
@@ -1396,18 +1397,21 @@ bool s1ap::ue::send_uectxtreleaserequest(const cause_c& cause)
 {
   if (was_uectxtrelease_requested()) {
     logger.warning("UE context for RNTI:0x%x is in zombie state. Releasing...", ctxt.rnti);
+    s1ap_ptr->rrc->release_ue(ctxt.rnti);
     s1ap_ptr->users.erase(this);
     return false;
   }
   if (not ctxt.mme_ue_s1ap_id.has_value()) {
     logger.error("Cannot send UE context release request without a MME-UE-S1AP-Id allocated.");
+    s1ap_ptr->rrc->release_ue(ctxt.rnti);
     s1ap_ptr->users.erase(this);
     return false;
   }
 
   if (ts1_reloc_overall.is_running()) {
-    logger.info("Not sending UEContextReleaseRequest for UE rnti=0x%x performing S1 Handover.", ctxt.rnti);
-    s1ap_ptr->users.erase(this);
+    logger.info("Ignoring UE context release request from lower layers for UE rnti=0x%x performing S1 Handover.",
+                ctxt.rnti);
+    // leave the UE context alive until ts1_reloc_overall expiry
     return false;
   }
 
@@ -1423,6 +1427,7 @@ bool s1ap::ue::send_uectxtreleaserequest(const cause_c& cause)
 
   release_requested = s1ap_ptr->sctp_send_s1ap_pdu(tx_pdu, ctxt.rnti, "UEContextReleaseRequest");
   if (not release_requested) {
+    s1ap_ptr->rrc->release_ue(ctxt.rnti);
     s1ap_ptr->users.erase(this);
   }
   return release_requested;