eMBMS: moving RRC add_user call for MRNTI to avoiding potential deadlock

srsenb/src/stack/mac/mac.cc

@@ -1056,7 +1056,6 @@ void mac::write_mcch(const srsran::sib2_mbms_t* sib2_,
   if (!ret) {
     logger.info("Failed to allocate rnti=0x%x.for eMBMS", SRSRAN_MRNTI);
   }
-  rrc_h->add_user(SRSRAN_MRNTI, {});
 }
 
 // Internal helper function, caller must hold UE DB rwlock

srsenb/src/stack/rrc/rrc.cc

@@ -951,6 +951,7 @@ void rrc::configure_mbsfn_sibs()
   task_sched.defer_task([this, sibs2, sibs13, mcch_t]() mutable {
     phy->configure_mbsfn(&sibs2, &sibs13, mcch_t);
     mac->write_mcch(&sibs2, &sibs13, &mcch_t, mcch_payload_buffer, current_mcch_length);
+    add_user(SRSRAN_MRNTI, {});
   });
 }