From eee4a0c6523c674cad4fe08dea2ce6469ad539f8 Mon Sep 17 00:00:00 2001
From: Robert Schmidt <robert.schmidt@openairinterface.org>
Date: Tue, 12 Mar 2024 18:56:08 +0100
Subject: [PATCH] UE: signal RLF to RRC

---
 openair2/COMMON/rrc_messages_def.h   |  3 +++
 openair2/COMMON/rrc_messages_types.h |  6 ++++++
 openair2/RRC/NR_UE/rrc_UE.c          | 18 ++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/openair2/COMMON/rrc_messages_def.h b/openair2/COMMON/rrc_messages_def.h
index ef09d98284..fb94aeb29e 100644
--- a/openair2/COMMON/rrc_messages_def.h
+++ b/openair2/COMMON/rrc_messages_def.h
@@ -85,3 +85,6 @@ MESSAGE_DEF(NRRRC_FRAME_PROCESS,        MESSAGE_PRIORITY_MED,       NRRrcFramePr
 // eNB: RLC -> RRC messages
 MESSAGE_DEF(RLC_SDU_INDICATION,         MESSAGE_PRIORITY_MED,       RlcSduIndication,           rlc_sdu_indication)
 MESSAGE_DEF(NAS_PDU_SESSION_REQ, MESSAGE_PRIORITY_MED, nas_pdu_session_req_t, nas_pdu_session_req)
+
+// UE: RLC -> RRC messages
+MESSAGE_DEF(NR_RRC_RLC_MAXRTX,          MESSAGE_PRIORITY_MED,       RlcMaxRtxIndication,        nr_rlc_maxrtx_indication)
diff --git a/openair2/COMMON/rrc_messages_types.h b/openair2/COMMON/rrc_messages_types.h
index 15509b1807..0e57120ee4 100644
--- a/openair2/COMMON/rrc_messages_types.h
+++ b/openair2/COMMON/rrc_messages_types.h
@@ -97,6 +97,8 @@
 #define NAS_OAI_TUN_NSA(mSGpTR)         (mSGpTR)->ittiMsg.nas_oai_tun_nsa
 #define NAS_PDU_SESSION_REQ(mSGpTR) (mSGpTR)->ittiMsg.nas_pdu_session_req
 
+#define NR_RRC_RLC_MAXRTX(mSGpTR) (mSGpTR)->ittiMsg.nr_rlc_maxrtx_indication
+
 //-------------------------------------------------------------------------------------------//
 typedef struct RrcStateInd_s {
   Rrc_State_t     state;
@@ -453,4 +455,8 @@ typedef struct rlc_sdu_indication_s {
   int message_id;
 } RlcSduIndication;
 
+typedef struct {
+  int ue_id;
+} RlcMaxRtxIndication;
+
 #endif /* RRC_MESSAGES_TYPES_H_ */
diff --git a/openair2/RRC/NR_UE/rrc_UE.c b/openair2/RRC/NR_UE/rrc_UE.c
index 5a65dcd71d..602795bc4c 100644
--- a/openair2/RRC/NR_UE/rrc_UE.c
+++ b/openair2/RRC/NR_UE/rrc_UE.c
@@ -873,6 +873,13 @@ static int8_t nr_rrc_ue_decode_NR_BCCH_DL_SCH_Message(NR_UE_RRC_INST_t *rrc,
   return 0;
 }
 
+static void nr_rrc_signal_maxrtxindication(int ue_id)
+{
+  MessageDef *msg = itti_alloc_new_message(TASK_RLC_UE, ue_id, NR_RRC_RLC_MAXRTX);
+  NR_RRC_RLC_MAXRTX(msg).ue_id = ue_id;
+  itti_send_msg_to_task(TASK_RRC_NRUE, ue_id, msg);
+}
+
 static void nr_rrc_manage_rlc_bearers(NR_UE_RRC_INST_t *rrc,
                                       const NR_CellGroupConfig_t *cellGroupConfig)
 {
@@ -901,9 +908,11 @@ static void nr_rrc_manage_rlc_bearers(NR_UE_RRC_INST_t *rrc,
         if (rlc_bearer->servedRadioBearer->present == NR_RLC_BearerConfig__servedRadioBearer_PR_srb_Identity) {
           NR_SRB_Identity_t srb_id = rlc_bearer->servedRadioBearer->choice.srb_Identity;
           nr_rlc_add_srb(rrc->ue_id, srb_id, rlc_bearer);
+          nr_rlc_set_rlf_handler(rrc->ue_id, nr_rrc_signal_maxrtxindication);
         } else { // DRB
           NR_DRB_Identity_t drb_id = rlc_bearer->servedRadioBearer->choice.drb_Identity;
           nr_rlc_add_drb(rrc->ue_id, drb_id, rlc_bearer);
+          nr_rlc_set_rlf_handler(rrc->ue_id, nr_rrc_signal_maxrtxindication);
         }
       }
     }
@@ -1843,6 +1852,15 @@ void *rrc_nrue(void *notUsed)
     nr_rrc_going_to_IDLE(rrc, release_cause, NULL);
     break;
 
+  case NR_RRC_RLC_MAXRTX:
+    // detection of RLF upon indication from RLC that the maximum number of retransmissions has been reached
+    LOG_W(NR_RRC,
+          "[UE %ld ID %d] Received indication that RLC reached max retransmissions\n",
+          instance,
+          NR_RRC_RLC_MAXRTX(msg_p).ue_id);
+    handle_rlf_detection(rrc);
+    break;
+
   case NR_RRC_MAC_MSG3_IND:
     nr_rrc_handle_msg3_indication(rrc, NR_RRC_MAC_MSG3_IND(msg_p).rnti);
     break;