cu_cp: make ue removal request awaitable

FabianEckermann · Fabian Eckermann · commit 9bb19c30c661 · 2024-03-22T15:09:30.000Z
diff --git a/include/srsran/rrc/rrc_ue.h b/include/srsran/rrc/rrc_ue.h
@@ -326,7 +326,7 @@ class rrc_ue_context_update_notifier
 
   /// \brief Notify the CU-CP to completly remove a UE from the CU-CP.
   /// \param[in] ue_index The index of the UE to remove.
-  virtual void on_ue_removal_required(ue_index_t ue_index) = 0;
+  virtual async_task<void> on_ue_removal_required(ue_index_t ue_index) = 0;
 };
 
 /// Interface to notify about measurements
diff --git a/lib/cu_cp/adapters/du_processor_adapters.h b/lib/cu_cp/adapters/du_processor_adapters.h
@@ -90,10 +90,10 @@ class du_processor_cu_cp_adapter : public du_processor_cu_cp_notifier
     cu_cp_handler->handle_rrc_ue_creation(ue_index, rrc_ue, *ngap_du_notifier);
   }
 
-  void on_ue_removal_required(ue_index_t ue_index) override
+  async_task<void> on_ue_removal_required(ue_index_t ue_index) override
   {
     srsran_assert(ue_removal_handler != nullptr, "CU-CP UE Removal handler must not be nullptr");
-    ue_removal_handler->handle_ue_removal_request(ue_index);
+    return ue_removal_handler->handle_ue_removal_request(ue_index);
   }
 
   async_task<bool> on_ue_transfer_required(ue_index_t ue_index, ue_index_t old_ue_index) override
diff --git a/lib/cu_cp/adapters/rrc_ue_adapters.h b/lib/cu_cp/adapters/rrc_ue_adapters.h
@@ -186,7 +186,7 @@ class rrc_ue_cu_cp_adapter : public rrc_ue_context_update_notifier, public rrc_u
     return cu_cp_rrc_ue_handler->handle_ue_context_transfer(ue_index, old_ue_index);
   }
 
-  void on_ue_removal_required(ue_index_t ue_index) override
+  async_task<void> on_ue_removal_required(ue_index_t ue_index) override
   {
     srsran_assert(ue_removal_handler != nullptr, "CU-CP UE removal handler must not be nullptr");
     return ue_removal_handler->handle_ue_removal_request(ue_index);
diff --git a/lib/cu_cp/cu_cp_impl.cpp b/lib/cu_cp/cu_cp_impl.cpp
@@ -10,6 +10,7 @@
 
 #include "cu_cp_impl.h"
 #include "metrics_handler/metrics_handler_impl.h"
+#include "routines/ue_removal_routine.h"
 #include "srsran/cu_cp/cu_cp_types.h"
 #include "srsran/f1ap/cu_cp/f1ap_cu.h"
 #include "srsran/ngap/ngap_factory.h"
@@ -51,7 +52,6 @@ cu_cp_impl::cu_cp_impl(const cu_cp_configuration& config_) :
                              conn_notifier,
                              srslog::fetch_basic_logger("CU-CP")}),
   cu_up_db(cu_up_repository_config{cfg, e1ap_ev_notifier, srslog::fetch_basic_logger("CU-CP")}),
-  routine_mng(ue_mng.get_task_sched()),
   controller(routine_mng, cfg.ngap_config, ngap_adapter, cu_up_db),
   metrics_hdlr(std::make_unique<metrics_handler_impl>(*cfg.cu_cp_executor, *cfg.timers, ue_mng, du_db))
 {
@@ -282,18 +282,19 @@ bool cu_cp_impl::handle_cell_config_update_request(nr_cell_id_t nci, const servi
   return cell_meas_mng.update_cell_config(nci, serv_cell_cfg);
 }
 
-void cu_cp_impl::handle_ue_removal_request(ue_index_t ue_index)
+async_task<void> cu_cp_impl::handle_ue_removal_request(ue_index_t ue_index)
 {
   du_index_t    du_index    = get_du_index_from_ue_index(ue_index);
   cu_up_index_t cu_up_index = uint_to_cu_up_index(0); // TODO: Update when mapping from UE index to CU-UP exists
   auto          e1_adapter  = e1ap_adapters.find(cu_up_index);
-  routine_mng.start_ue_removal_routine(ue_index,
-                                       rrc_du_adapters.at(du_index),
-                                       e1_adapter != e1ap_adapters.end() ? &e1_adapter->second : nullptr,
-                                       f1ap_adapters.at(du_index),
-                                       ngap_adapter,
-                                       ue_mng,
-                                       logger);
+
+  return launch_async<ue_removal_routine>(ue_index,
+                                          rrc_du_adapters.at(du_index),
+                                          e1_adapter != e1ap_adapters.end() ? &e1_adapter->second : nullptr,
+                                          f1ap_adapters.at(du_index),
+                                          ngap_adapter,
+                                          ue_mng,
+                                          logger);
 }
 
 // private
diff --git a/lib/cu_cp/cu_cp_impl.h b/lib/cu_cp/cu_cp_impl.h
@@ -71,7 +71,7 @@ class cu_cp_impl final : public cu_cp, public cu_cp_impl_interface, public cu_cp
   bool handle_cell_config_update_request(nr_cell_id_t nci, const serving_cell_meas_config& serv_cell_cfg) override;
 
   // cu_cp_ue_removal_interface
-  void handle_ue_removal_request(ue_index_t ue_index) override;
+  async_task<void> handle_ue_removal_request(ue_index_t ue_index) override;
 
   metrics_handler& get_metrics_handler() override { return *metrics_hdlr; }
 
diff --git a/lib/cu_cp/cu_cp_impl_interface.h b/lib/cu_cp/cu_cp_impl_interface.h
@@ -269,7 +269,7 @@ class cu_cp_ue_removal_handler
 
   /// \brief Completly remove a UE from the CU-CP.
   /// \param[in] ue_index The index of the UE to remove.
-  virtual void handle_ue_removal_request(ue_index_t ue_index) = 0;
+  virtual async_task<void> handle_ue_removal_request(ue_index_t ue_index) = 0;
 };
 
 class cu_cp_impl_interface : public cu_cp_e1ap_handler,
diff --git a/lib/cu_cp/du_processor/du_processor_impl.cpp b/lib/cu_cp/du_processor/du_processor_impl.cpp
@@ -257,7 +257,7 @@ du_processor_impl::handle_ue_rrc_context_creation_request(const ue_rrc_context_c
   du_cell_index_t pcell_index = find_cell(req.cgi.nci);
   if (pcell_index == du_cell_index_t::invalid) {
     logger.warning("ue={}: Could not find cell with NCI={}", req.ue_index, req.cgi.nci);
-    cu_cp_notifier.on_ue_removal_required(req.ue_index);
+    task_sched.schedule_async_task(req.ue_index, cu_cp_notifier.on_ue_removal_required(req.ue_index));
     return {};
   }
   const pci_t pci = cell_db.at(pcell_index).pci;
diff --git a/lib/cu_cp/du_processor/du_processor_impl_interface.h b/lib/cu_cp/du_processor/du_processor_impl_interface.h
@@ -366,7 +366,7 @@ class du_processor_cu_cp_notifier
 
   /// \brief Notify the CU-CP to completly remove a UE from the CU-CP.
   /// \param[in] ue_index The index of the UE to remove.
-  virtual void on_ue_removal_required(ue_index_t ue_index) = 0;
+  virtual async_task<void> on_ue_removal_required(ue_index_t ue_index) = 0;
 
   /// \brief Notify the CU-CP to transfer and remove ue contexts.
   /// \param[in] ue_index The new UE index of the UE that sent the Reestablishment Request.
diff --git a/lib/cu_cp/routine_managers/cu_cp_routine_manager.cpp b/lib/cu_cp/routine_managers/cu_cp_routine_manager.cpp
@@ -16,26 +16,9 @@
 using namespace srsran;
 using namespace srs_cu_cp;
 
-cu_cp_routine_manager::cu_cp_routine_manager(ue_task_scheduler_manager& ue_task_sched_) :
-  ue_task_sched(ue_task_sched_), main_ctrl_loop(128)
-{
-}
+cu_cp_routine_manager::cu_cp_routine_manager() : main_ctrl_loop(128) {}
 
 bool cu_cp_routine_manager::schedule_async_task(async_task<void> task)
 {
   return main_ctrl_loop.schedule(std::move(task));
 }
-
-void cu_cp_routine_manager::start_ue_removal_routine(ue_index_t                      ue_index,
-                                                     cu_cp_rrc_ue_removal_notifier&  rrc_du_notifier,
-                                                     cu_cp_e1ap_ue_removal_notifier* e1ap_notifier,
-                                                     cu_cp_f1ap_ue_removal_notifier& f1ap_notifier,
-                                                     cu_cp_ngap_control_notifier&    ngap_notifier,
-                                                     ue_manager&                     ue_mng,
-                                                     srslog::basic_logger&           logger)
-{
-  ue_task_sched.handle_ue_async_task(
-      ue_index,
-      launch_async<ue_removal_routine>(
-          ue_index, rrc_du_notifier, e1ap_notifier, f1ap_notifier, ngap_notifier, ue_mng, logger));
-}
diff --git a/lib/cu_cp/routine_managers/cu_cp_routine_manager.h b/lib/cu_cp/routine_managers/cu_cp_routine_manager.h
@@ -29,24 +29,12 @@ namespace srs_cu_cp {
 class cu_cp_routine_manager
 {
 public:
-  explicit cu_cp_routine_manager(ue_task_scheduler_manager& ue_task_sched_);
+  explicit cu_cp_routine_manager();
   ~cu_cp_routine_manager() = default;
 
   bool schedule_async_task(async_task<void> task);
 
-  void start_initial_cu_cp_setup_routine(const ngap_configuration& ngap_cfg);
-
-  void start_ue_removal_routine(ue_index_t                      ue_index,
-                                cu_cp_rrc_ue_removal_notifier&  rrc_du_notifier,
-                                cu_cp_e1ap_ue_removal_notifier* e1ap_notifier,
-                                cu_cp_f1ap_ue_removal_notifier& f1ap_notifier,
-                                cu_cp_ngap_control_notifier&    ngap_notifier,
-                                ue_manager&                     ue_mng,
-                                srslog::basic_logger&           logger);
-
 private:
-  ue_task_scheduler_manager& ue_task_sched;
-
   // cu-cp task event loop
   fifo_async_task_scheduler main_ctrl_loop;
 };
diff --git a/lib/cu_cp/routines/mobility/inter_cu_handover_target_routine.cpp b/lib/cu_cp/routines/mobility/inter_cu_handover_target_routine.cpp
@@ -120,7 +120,8 @@ void inter_cu_handover_target_routine::operator()(
     if (!handle_procedure_response(
             bearer_context_modification_request, ue_context_setup_response, next_config, logger)) {
       logger.warning("ue={}: \"{}\" failed to setup UE context at DU", request.ue_index, name());
-      cu_cp_notifier.on_ue_removal_required(ue_context_setup_response.ue_index);
+      CORO_AWAIT(cu_cp_notifier.on_ue_removal_required(ue_context_setup_response.ue_index));
+      // Note: From this point the UE is removed and only the stored context can be accessed.
       CORO_EARLY_RETURN(generate_handover_resource_allocation_response(false));
     }
   }
diff --git a/lib/cu_cp/routines/mobility/inter_du_handover_routine.cpp b/lib/cu_cp/routines/mobility/inter_du_handover_routine.cpp
@@ -111,7 +111,8 @@ void inter_du_handover_routine::operator()(coro_context<async_task<cu_cp_inter_d
                                        logger,
                                        false)) {
       logger.warning("ue={}: \"{}\" failed to create UE context at target DU", command.source_ue_index, name());
-      cu_cp_notifier.on_ue_removal_required(target_ue_context_setup_request.ue_index);
+      CORO_AWAIT(cu_cp_notifier.on_ue_removal_required(target_ue_context_setup_request.ue_index));
+      // Note: From this point the UE is removed and only the stored context can be accessed.
       CORO_EARLY_RETURN(response_msg);
     }
   }
diff --git a/lib/cu_cp/routines/ue_context_release_routine.cpp b/lib/cu_cp/routines/ue_context_release_routine.cpp
@@ -71,7 +71,8 @@ void ue_context_release_routine::operator()(coro_context<async_task<cu_cp_ue_con
 
   {
     // Remove UE
-    cu_cp_notifier.on_ue_removal_required(command.ue_index);
+    CORO_AWAIT(cu_cp_notifier.on_ue_removal_required(command.ue_index));
+    // Note: From this point the UE is removed and only the stored context can be accessed.
   }
 
   CORO_RETURN(release_complete);
diff --git a/lib/rrc/ue/procedures/rrc_reestablishment_procedure.cpp b/lib/rrc/ue/procedures/rrc_reestablishment_procedure.cpp
@@ -117,7 +117,9 @@ void rrc_reestablishment_procedure::operator()(coro_context<async_task<void>>& c
   }
 
   // Notify CU-CP to remove the old UE
-  cu_cp_notifier.on_ue_removal_required(reestablishment_context.ue_index);
+  CORO_AWAIT(cu_cp_notifier.on_ue_removal_required(reestablishment_context.ue_index));
+
+  // Note: From this point the UE is removed and only the stored context can be accessed.
 
   CORO_RETURN();
 }
diff --git a/tests/unittests/cu_cp/test_helpers.h b/tests/unittests/cu_cp/test_helpers.h
@@ -98,7 +98,7 @@ struct dummy_du_processor_cu_cp_notifier : public du_processor_cu_cp_notifier {
     }
   }
 
-  void on_ue_removal_required(ue_index_t ue_index) override
+  async_task<void> on_ue_removal_required(ue_index_t ue_index) override
   {
     logger.info("ue={}: Received a UE removal request", ue_index);
 
@@ -113,6 +113,11 @@ struct dummy_du_processor_cu_cp_notifier : public du_processor_cu_cp_notifier {
         rrc_removal_handler->remove_ue(ue_index);
       }
     }
+
+    return launch_async([](coro_context<async_task<void>>& ctx) mutable {
+      CORO_BEGIN(ctx);
+      CORO_RETURN();
+    });
   }
 
   async_task<bool> on_ue_transfer_required(ue_index_t ue_index, ue_index_t old_ue_index) override
diff --git a/tests/unittests/rrc/test_helpers.h b/tests/unittests/rrc/test_helpers.h
@@ -131,7 +131,14 @@ class dummy_rrc_ue_cu_cp_adapter : public rrc_ue_context_update_notifier, public
     });
   }
 
-  void on_ue_removal_required(ue_index_t ue_index) override { logger.info("ue={}: Requested a UE removal", ue_index); }
+  async_task<void> on_ue_removal_required(ue_index_t ue_index) override
+  {
+    logger.info("ue={}: Requested a UE removal", ue_index);
+    return launch_async([](coro_context<async_task<void>>& ctx) mutable {
+      CORO_BEGIN(ctx);
+      CORO_RETURN();
+    });
+  }
 
   optional<rrc_meas_cfg> on_measurement_config_request(ue_index_t             ue_index,
                                                        nr_cell_id_t           nci,

Original file line number	Diff line number	Diff line change
`@@ -90,10 +90,10 @@ class du_processor_cu_cp_adapter : public du_processor_cu_cp_notifier`
`90`	`90`	`cu_cp_handler->handle_rrc_ue_creation(ue_index, rrc_ue, *ngap_du_notifier);`
`91`	`91`	`}`
`92`	`92`
`93`		`- void on_ue_removal_required(ue_index_t ue_index) override`
	`93`	`+ async_task<void> on_ue_removal_required(ue_index_t ue_index) override`
`94`	`94`	`{`
`95`	`95`	`srsran_assert(ue_removal_handler != nullptr, "CU-CP UE Removal handler must not be nullptr");`
`96`		`- ue_removal_handler->handle_ue_removal_request(ue_index);`
	`96`	`+ return ue_removal_handler->handle_ue_removal_request(ue_index);`
`97`	`97`	`}`
`98`	`98`
`99`	`99`	`async_task<bool> on_ue_transfer_required(ue_index_t ue_index, ue_index_t old_ue_index) override`
Original file line number	Diff line number	Diff line change
`@@ -186,7 +186,7 @@ class rrc_ue_cu_cp_adapter : public rrc_ue_context_update_notifier, public rrc_u`
`186`	`186`	`return cu_cp_rrc_ue_handler->handle_ue_context_transfer(ue_index, old_ue_index);`
`187`	`187`	`}`
`188`	`188`
`189`		`- void on_ue_removal_required(ue_index_t ue_index) override`
	`189`	`+ async_task<void> on_ue_removal_required(ue_index_t ue_index) override`
`190`	`190`	`{`
`191`	`191`	`srsran_assert(ue_removal_handler != nullptr, "CU-CP UE removal handler must not be nullptr");`
`192`	`192`	`return ue_removal_handler->handle_ue_removal_request(ue_index);`
Original file line number	Diff line number	Diff line change
`@@ -257,7 +257,7 @@ du_processor_impl::handle_ue_rrc_context_creation_request(const ue_rrc_context_c`
`257`	`257`	`du_cell_index_t pcell_index = find_cell(req.cgi.nci);`
`258`	`258`	`if (pcell_index == du_cell_index_t::invalid) {`
`259`	`259`	`logger.warning("ue={}: Could not find cell with NCI={}", req.ue_index, req.cgi.nci);`
`260`		`- cu_cp_notifier.on_ue_removal_required(req.ue_index);`
	`260`	`+ task_sched.schedule_async_task(req.ue_index, cu_cp_notifier.on_ue_removal_required(req.ue_index));`
`261`	`261`	`return {};`
`262`	`262`	`}`
`263`	`263`	`const pci_t pci = cell_db.at(pcell_index).pci;`