cu-cp: fix for drb removal

lib/cu_cp/du_processor/du_processor_impl.cpp

@@ -395,7 +395,7 @@ du_processor_impl::handle_new_pdu_session_resource_release_command(
   srsran_assert(ue != nullptr, "ue={}: Could not find DU UE", msg.ue_index);
 
   return routine_mng->start_pdu_session_resource_release_routine(
-      msg, ngap_ctrl_notifier, task_sched, ue->get_up_resource_manager());
+      msg, ngap_ctrl_notifier, ue->get_rrc_ue_notifier(), task_sched, ue->get_up_resource_manager());
 }
 
 void du_processor_impl::handle_paging_message(cu_cp_paging_message& msg)

lib/cu_cp/routine_managers/du_processor_routine_manager.cpp

@@ -80,13 +80,15 @@ async_task<cu_cp_pdu_session_resource_release_response>
 du_processor_routine_manager::start_pdu_session_resource_release_routine(
     const cu_cp_pdu_session_resource_release_command& release_cmd,
     du_processor_ngap_control_notifier&               ngap_ctrl_notifier,
+    du_processor_rrc_ue_control_message_notifier&     rrc_ue_ctrl_notifier,
     du_processor_ue_task_scheduler&                   task_sched,
     up_resource_manager&                              rrc_ue_up_resource_manager)
 {
   return launch_async<pdu_session_resource_release_routine>(release_cmd,
                                                             e1ap_ctrl_notifier,
                                                             f1ap_ue_ctxt_notifier,
                                                             ngap_ctrl_notifier,
+                                                            rrc_ue_ctrl_notifier,
                                                             task_sched,
                                                             rrc_ue_up_resource_manager,
                                                             logger);

lib/cu_cp/routine_managers/du_processor_routine_manager.h

@@ -49,6 +49,7 @@ class du_processor_routine_manager
   async_task<cu_cp_pdu_session_resource_release_response>
   start_pdu_session_resource_release_routine(const cu_cp_pdu_session_resource_release_command& release_cmd,
                                              du_processor_ngap_control_notifier&               ngap_ctrl_notifier,
+                                             du_processor_rrc_ue_control_message_notifier&     rrc_ue_ctrl_notifier,
                                              du_processor_ue_task_scheduler&                   task_sched,
                                              up_resource_manager& rrc_ue_up_resource_manager);
 

lib/cu_cp/routines/mobility/inter_cu_handover_target_routine.cpp

@@ -167,6 +167,7 @@ void inter_cu_handover_target_routine::operator()(
     if (!fill_rrc_reconfig_args(rrc_reconfig_args,
                                 ue_context_setup_request.srbs_to_be_setup_list,
                                 next_config.pdu_sessions_to_setup_list,
+                                {} /* No DRB to be removed */,
                                 ue_context_setup_response.du_to_cu_rrc_info,
                                 {} /* No NAS PDUs required */,
                                 ue->get_rrc_ue_notifier().generate_meas_config(),

lib/cu_cp/routines/mobility/inter_du_handover_routine.cpp

@@ -176,6 +176,7 @@ void inter_du_handover_routine::operator()(coro_context<async_task<cu_cp_inter_d
       if (!fill_rrc_reconfig_args(rrc_reconfig_args,
                                   target_ue_context_setup_request.srbs_to_be_setup_list,
                                   next_config.pdu_sessions_to_setup_list,
+                                  {} /* No DRB to be removed */,
                                   target_ue_context_setup_response.du_to_cu_rrc_info,
                                   {} /* No NAS PDUs required */,
                                   target_ue->get_rrc_ue_notifier().generate_meas_config(source_rrc_context.meas_cfg),

lib/cu_cp/routines/pdu_session_resource_modification_routine.cpp

@@ -151,16 +151,17 @@ void pdu_session_resource_modification_routine::operator()(
     // prepare RRC Reconfiguration and call RRC UE notifier
     {
       // get NAS PDUs as received by AMF
-      std::map<pdu_session_id_t, byte_buffer> nas_pdus;
+      std::vector<byte_buffer> nas_pdus;
       for (const auto& pdu_session : modify_request.pdu_session_res_modify_items) {
         if (!pdu_session.nas_pdu.empty()) {
-          nas_pdus.emplace(pdu_session.pdu_session_id, pdu_session.nas_pdu);
+          nas_pdus.push_back(pdu_session.nas_pdu);
         }
       }
 
       if (!fill_rrc_reconfig_args(rrc_reconfig_args,
                                   {},
                                   next_config.pdu_sessions_to_modify_list,
+                                  {} /* No extra DRB to be removed */,
                                   ue_context_modification_response.du_to_cu_rrc_info,
                                   nas_pdus,
                                   rrc_ue_notifier.generate_meas_config(),

lib/cu_cp/routines/pdu_session_resource_release_routine.cpp

@@ -21,6 +21,7 @@
  */
 
 #include "pdu_session_resource_release_routine.h"
+#include "pdu_session_routine_helpers.h"
 
 using namespace srsran;
 using namespace srsran::srs_cu_cp;
@@ -31,19 +32,35 @@ pdu_session_resource_release_routine::pdu_session_resource_release_routine(
     du_processor_e1ap_control_notifier&               e1ap_ctrl_notif_,
     du_processor_f1ap_ue_context_notifier&            f1ap_ue_ctxt_notif_,
     du_processor_ngap_control_notifier&               ngap_ctrl_notifier_,
+    du_processor_rrc_ue_control_message_notifier&     rrc_ue_notifier_,
     du_processor_ue_task_scheduler&                   task_sched_,
     up_resource_manager&                              rrc_ue_up_resource_manager_,
     srslog::basic_logger&                             logger_) :
   release_cmd(release_cmd_),
   e1ap_ctrl_notifier(e1ap_ctrl_notif_),
   f1ap_ue_ctxt_notifier(f1ap_ue_ctxt_notif_),
   ngap_ctrl_notifier(ngap_ctrl_notifier_),
+  rrc_ue_notifier(rrc_ue_notifier_),
   task_sched(task_sched_),
   rrc_ue_up_resource_manager(rrc_ue_up_resource_manager_),
   logger(logger_)
 {
 }
 
+// Handle RRC reconfiguration result.
+bool handle_procedure_response(cu_cp_pdu_session_resource_release_response&      response_msg,
+                               const cu_cp_pdu_session_resource_release_command& release_cmd,
+                               bool                                              rrc_reconfig_result,
+                               const srslog::basic_logger&                       logger)
+{
+  // Let all PDU sessions fail if response is negative.
+  if (!rrc_reconfig_result) {
+    // TODO: decide how to manage negative RRC reconfig result
+  }
+
+  return rrc_reconfig_result;
+}
+
 void pdu_session_resource_release_routine::operator()(
     coro_context<async_task<cu_cp_pdu_session_resource_release_response>>& ctx)
 {
@@ -54,7 +71,7 @@ void pdu_session_resource_release_routine::operator()(
   // Perform initial sanity checks on incoming message.
   if (!rrc_ue_up_resource_manager.validate_request(release_cmd)) {
     logger.warning("ue={}: \"{}\" Invalid PduSessionResourceReleaseCommand", release_cmd.ue_index, name());
-    CORO_EARLY_RETURN(generate_pdu_session_resource_release_response(false));
+    CORO_EARLY_RETURN(handle_pdu_session_resource_release_response(false));
   }
 
   {
@@ -113,13 +130,48 @@ void pdu_session_resource_release_routine::operator()(
     }
   }
 
-  CORO_RETURN(generate_pdu_session_resource_release_response(true));
+  {
+    // prepare RRC Reconfiguration and call RRC UE notifier
+    {
+      // get NAS PDUs as received by AMF
+      std::vector<byte_buffer> nas_pdus;
+      if (!release_cmd.nas_pdu.empty()) {
+        nas_pdus.push_back(release_cmd.nas_pdu);
+      }
+
+      if (!fill_rrc_reconfig_args(rrc_reconfig_args,
+                                  {},
+                                  next_config.pdu_sessions_to_modify_list,
+                                  next_config.drb_to_remove_list,
+                                  ue_context_modification_response.du_to_cu_rrc_info,
+                                  nas_pdus,
+                                  rrc_ue_notifier.generate_meas_config(),
+                                  false,
+                                  false,
+                                  false,
+                                  logger)) {
+        logger.warning("ue={}: \"{}\" Failed to fill RrcReconfiguration", release_cmd.ue_index, name());
+        CORO_EARLY_RETURN(handle_pdu_session_resource_release_response(false));
+      }
+    }
+
+    CORO_AWAIT_VALUE(rrc_reconfig_result, rrc_ue_notifier.on_rrc_reconfiguration_request(rrc_reconfig_args));
+
+    // Handle RRC Reconfiguration result.
+    if (handle_procedure_response(response_msg, release_cmd, rrc_reconfig_result, logger) == false) {
+      logger.warning("ue={}: \"{}\" RRC reconfiguration failed", release_cmd.ue_index, name());
+      CORO_EARLY_RETURN(handle_pdu_session_resource_release_response(false));
+    }
+  }
+
+  CORO_RETURN(handle_pdu_session_resource_release_response(true));
 }
 
 cu_cp_pdu_session_resource_release_response
-pdu_session_resource_release_routine::generate_pdu_session_resource_release_response(bool success)
+pdu_session_resource_release_routine::handle_pdu_session_resource_release_response(bool success)
 {
   if (success) {
+    logger.debug("ue={}: \"{}\" finalized", release_cmd.ue_index, name());
     for (const auto& setup_item : release_cmd.pdu_session_res_to_release_list_rel_cmd) {
       cu_cp_pdu_session_res_released_item_rel_res item;
       item.pdu_session_id = setup_item.pdu_session_id;
@@ -136,7 +188,11 @@ pdu_session_resource_release_routine::generate_pdu_session_resource_release_resp
     }
 
     rrc_ue_up_resource_manager.apply_config_update(result);
+  } else {
+    logger.info("ue={}: \"{}\" failed", release_cmd.ue_index, name());
+
+    // Trigger UE context release request?
   }
 
   return response_msg;
-}
+}

lib/cu_cp/routines/pdu_session_resource_release_routine.h

@@ -38,9 +38,11 @@ class pdu_session_resource_release_routine
                                        du_processor_e1ap_control_notifier&               e1ap_ctrl_notif_,
                                        du_processor_f1ap_ue_context_notifier&            f1ap_ue_ctxt_notif_,
                                        du_processor_ngap_control_notifier&               ngap_ctrl_notifier_,
+                                       du_processor_rrc_ue_control_message_notifier&     rrc_ue_notifier_,
                                        du_processor_ue_task_scheduler&                   task_sched_,
-                                       up_resource_manager&                              rrc_ue_up_resource_manager_,
-                                       srslog::basic_logger&                             logger_);
+
+                                       up_resource_manager&  rrc_ue_up_resource_manager_,
+                                       srslog::basic_logger& logger_);
 
   void operator()(coro_context<async_task<cu_cp_pdu_session_resource_release_response>>& ctx);
 
@@ -50,30 +52,33 @@ class pdu_session_resource_release_routine
   void fill_e1ap_bearer_context_modification_request(e1ap_bearer_context_modification_request& e1ap_request);
   bool valid_5qi(const qos_flow_setup_request_item& flow);
 
-  cu_cp_pdu_session_resource_release_response generate_pdu_session_resource_release_response(bool success);
+  cu_cp_pdu_session_resource_release_response handle_pdu_session_resource_release_response(bool success);
 
   const cu_cp_pdu_session_resource_release_command release_cmd;
 
   up_config_update next_config;
 
-  du_processor_e1ap_control_notifier&    e1ap_ctrl_notifier;         // to trigger bearer context setup at CU-UP
-  du_processor_f1ap_ue_context_notifier& f1ap_ue_ctxt_notifier;      // to trigger UE context modification at DU
-  du_processor_ngap_control_notifier&    ngap_ctrl_notifier;         // to request UE release
-  du_processor_ue_task_scheduler&        task_sched;                 // to schedule UE release request (over NGAP)
-  up_resource_manager&                   rrc_ue_up_resource_manager; // to get RRC DRB config
-  srslog::basic_logger&                  logger;
+  du_processor_e1ap_control_notifier&           e1ap_ctrl_notifier;    // to trigger bearer context setup at CU-UP
+  du_processor_f1ap_ue_context_notifier&        f1ap_ue_ctxt_notifier; // to trigger UE context modification at DU
+  du_processor_ngap_control_notifier&           ngap_ctrl_notifier;    // to request UE release
+  du_processor_rrc_ue_control_message_notifier& rrc_ue_notifier;       // to trigger RRC Reconfiguration at UE
+  du_processor_ue_task_scheduler&               task_sched;            // to schedule UE release request (over NGAP)
+  up_resource_manager&                          rrc_ue_up_resource_manager; // to get RRC DRB config
+  srslog::basic_logger&                         logger;
 
   // (sub-)routine requests
   f1ap_ue_context_modification_request     ue_context_mod_request;
   e1ap_bearer_context_modification_request bearer_context_modification_request;
   e1ap_bearer_context_release_command      bearer_context_release_command;
+  rrc_reconfiguration_procedure_request    rrc_reconfig_args;
   cu_cp_ue_context_release_request         ue_context_release_request;
 
   // (sub-)routine results
   cu_cp_pdu_session_resource_release_response response_msg;
   f1ap_ue_context_modification_response       ue_context_modification_response; // to inform DU about the new DRBs
   e1ap_bearer_context_modification_response
-      bearer_context_modification_response; // to inform CU-UP about the new TEID for UL F1u traffic
+       bearer_context_modification_response; // to inform CU-UP about the new TEID for UL F1u traffic
+  bool rrc_reconfig_result = false;          // the final UE reconfiguration
 };
 
 } // namespace srs_cu_cp

lib/cu_cp/routines/pdu_session_resource_setup_routine.cpp

@@ -211,16 +211,17 @@ void pdu_session_resource_setup_routine::operator()(
     // if default DRB is being setup, SRB2 needs to be setup as well
     {
       // get NAS PDUs as received by AMF
-      std::map<pdu_session_id_t, byte_buffer> nas_pdus;
+      std::vector<byte_buffer> nas_pdus;
       for (const auto& pdu_session : setup_msg.pdu_session_res_setup_items) {
         if (!pdu_session.pdu_session_nas_pdu.empty()) {
-          nas_pdus.emplace(pdu_session.pdu_session_id, pdu_session.pdu_session_nas_pdu);
+          nas_pdus.push_back(pdu_session.pdu_session_nas_pdu);
         }
       }
 
       if (!fill_rrc_reconfig_args(rrc_reconfig_args,
                                   ue_context_mod_request.srbs_to_be_setup_mod_list,
                                   next_config.pdu_sessions_to_setup_list,
+                                  {} /* No extra DRB to be removed */,
                                   ue_context_modification_response.du_to_cu_rrc_info,
                                   nas_pdus,
                                   next_config.initial_context_creation ? rrc_ue_notifier.generate_meas_config()

lib/cu_cp/routines/pdu_session_routine_helpers.cpp

@@ -88,8 +88,9 @@ bool srsran::srs_cu_cp::fill_rrc_reconfig_args(
     rrc_reconfiguration_procedure_request&                             rrc_reconfig_args,
     const slotted_id_vector<srb_id_t, f1ap_srbs_to_be_setup_mod_item>& srbs_to_be_setup_mod_list,
     const std::map<pdu_session_id_t, up_pdu_session_context_update>&   pdu_sessions,
+    const std::vector<drb_id_t>&                                       drb_to_remove,
     const f1ap_du_to_cu_rrc_info&                                      du_to_cu_rrc_info,
-    const std::map<pdu_session_id_t, byte_buffer>&                     nas_pdus,
+    const std::vector<byte_buffer>&                                    nas_pdus,
     const optional<rrc_meas_cfg>                                       rrc_meas_cfg,
     bool                                                               reestablish_srbs,
     bool                                                               reestablish_drbs,
@@ -142,18 +143,27 @@ bool srsran::srs_cu_cp::fill_rrc_reconfig_args(
       radio_bearer_config.drb_to_add_mod_list.emplace(drb_to_add.first, drb_to_add_mod);
     }
 
-    for (const auto& drb_to_remove : pdu_session_to_add_mod.second.drb_to_remove) {
-      radio_bearer_config.drb_to_release_list.push_back(drb_to_remove);
+    // Remove DRB from a PDU session (PDU session itself still exists with out DRBs).
+    for (const auto& drb_id : pdu_session_to_add_mod.second.drb_to_remove) {
+      radio_bearer_config.drb_to_release_list.push_back(drb_id);
     }
+  }
 
-    // append NAS PDUs as received by AMF
-    if (!nas_pdus.empty()) {
-      if (nas_pdus.find(pdu_session_to_add_mod.first) != nas_pdus.end()) {
-        if (!nas_pdus.at(pdu_session_to_add_mod.first).empty()) {
-          rrc_recfg_v1530_ies.ded_nas_msg_list.push_back(nas_pdus.at(pdu_session_to_add_mod.first).copy());
-        }
-      }
+  // Remove DRB (if not already) that are not associated with any PDU session anymore.
+  for (const auto& drb_id : drb_to_remove) {
+    if (std::any_of(radio_bearer_config.drb_to_release_list.begin(),
+                    radio_bearer_config.drb_to_release_list.end(),
+                    [drb_id](const auto& item) { return item == drb_id; })) {
+      // The DRB is already set to be removed.
+      continue;
     }
+
+    radio_bearer_config.drb_to_release_list.push_back(drb_id);
+  }
+
+  // append NAS PDUs as received by AMF
+  for (const auto& nas_pdu : nas_pdus) {
+    rrc_recfg_v1530_ies.ded_nas_msg_list.push_back(nas_pdu.copy());
   }
 
   if (update_keys) {

lib/cu_cp/routines/pdu_session_routine_helpers.h

@@ -61,8 +61,9 @@ void fill_drb_to_remove_list(std::vector<drb_id_t>&       e1ap_drb_to_remove_lis
 /// \brief Fill RRC Reconfiguration message content.
 /// \param[out] rrc_reconfig_args The RRC Reconfiguration Arguments struct to fill.
 /// \param[in] srbs_to_be_setup_mod_list SRBs to be setup (only needed if default DRB is being setup).
-/// \param[in] pdu_sessions The PDU sessions to add to the reconfiguration.
-/// \param[in] ue_context_modification_response The UE Context Modification Response as received by the DU.
+/// \param[in] pdu_sessions The PDU sessions to add/mod in the reconfiguration.
+/// \param[in] drb_to_remove DRB to remove from the configurations.
+/// \param[in] du_to_cu_rrc_info RRC container forwarded from the DU to the CU.
 /// \param[in] nas_pdus NAS PDUs to forward to the UE as received by the AMF.
 /// \param[in] rrc_meas_cfg Optional measurement config to include in Reconfiguration.
 /// \param[in] reestablish_srbs Whether to request SRB reestablishment.
@@ -73,8 +74,9 @@ bool fill_rrc_reconfig_args(
     rrc_reconfiguration_procedure_request&                             rrc_reconfig_args,
     const slotted_id_vector<srb_id_t, f1ap_srbs_to_be_setup_mod_item>& srbs_to_be_setup_mod_list,
     const std::map<pdu_session_id_t, up_pdu_session_context_update>&   pdu_sessions,
+    const std::vector<drb_id_t>&                                       drb_to_remove,
     const f1ap_du_to_cu_rrc_info&                                      du_to_cu_rrc_info,
-    const std::map<pdu_session_id_t, byte_buffer>&                     nas_pdus,
+    const std::vector<byte_buffer>&                                    nas_pdus,
     const optional<rrc_meas_cfg>                                       rrc_meas_cfg,
     bool                                                               reestablish_srbs,
     bool                                                               reestablish_drbs,

lib/cu_cp/routines/reestablishment_context_modification_routine.cpp

@@ -124,6 +124,7 @@ void reestablishment_context_modification_routine::operator()(coro_context<async
       if (!fill_rrc_reconfig_args(rrc_reconfig_args,
                                   srbs_to_setup_list,
                                   pdu_sessions_to_setup_list,
+                                  {} /* No DRB to be removed */,
                                   ue_context_modification_response.du_to_cu_rrc_info,
                                   {},
                                   {} /* TODO: include meas config in context*/,