CFRA: handle potential Msg3

Since the parent commit, CFRA is inconditionally marked complete on Msg3
reception (successful or not). This works because the current
implementation still sends a UL grant (see parent commit for details).

In this commit, handle Msg3 if received in CFRA (notably for TA and
power). Note that since we declare RA complete, UE->ra does not exist
anymore, and so an intermediate variable is introduced to capture the
CFRA flag. The code should be such that if we are in CFRA, we never
access any UE->ra variable.

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -766,6 +766,7 @@ static void nr_rx_ra_sdu(const module_id_t mod_id,
   // nr_generate_Msg2()). We did not mark RA as complete right away, as the
   // DLSCH scheduler might schedule in the same slot as Msg2 if RLC has data
   // (which can only happen in do-ra), so we mark it as complete now.
+  bool cfra = ra->cfra;
   if (ra->cfra) {
     NR_UE_sched_ctrl_t *sched_ctrl = &UE->UE_sched_ctrl;
     nr_mac_reset_ul_failure(sched_ctrl);
@@ -784,11 +785,13 @@ static void nr_rx_ra_sdu(const module_id_t mod_id,
     } else {
       LOG_A(NR_MAC, "(rnti 0x%04x) CFRA procedure succeeded!\n", UE->rnti);
     }
-    return; // TODO: handle Msg3 in case it has been received?
   }
 
   const int target_snrx10 = mac->pusch_target_snrx10;
   if (!sdu) { // NACK
+    if (cfra)  // no Msg3 on CFRA, no problem
+      return;
+
     if (ra->ra_state != nrRA_WAIT_Msg3)
       return;
 
@@ -818,10 +821,11 @@ static void nr_rx_ra_sdu(const module_id_t mod_id,
 
   if (no_sig) {
     LOG_W(NR_MAC, "MSG3 ULSCH with no signal\n");
-    handle_msg3_failed_rx(mac, ra, rnti, mac->ul_bler.harq_round_max);
+    if (!cfra)
+      handle_msg3_failed_rx(mac, ra, rnti, mac->ul_bler.harq_round_max);
     return;
   }
-  if (ra->ra_type == RA_2_STEP) {
+  if (!cfra && ra->ra_type == RA_2_STEP) {
     // random access pusch with RA-RNTI
     if (ra->RA_rnti != rnti) {
       LOG_E(NR_MAC, "expected TC_RNTI %04x to match current RNTI %04x\n", ra->RA_rnti, rnti);
@@ -894,6 +898,9 @@ static void nr_rx_ra_sdu(const module_id_t mod_id,
     return;
   }
 
+  if (cfra)
+    return; // rest not relevant for CFRA
+
   // UE Contention Resolution Identity
   // Store the first 48 bits belonging to the uplink CCCH SDU within Msg3 to fill in Msg4
   // First byte corresponds to R/LCID MAC sub-header