eMBMS: pushing bsr update to task queue to avoid potential deadlock

srsenb/src/stack/mac/mac.cc

@@ -130,17 +130,20 @@ void mac::start_pcap_net(srsran::mac_pcap_net* pcap_net_)
 
 int mac::rlc_buffer_state(uint16_t rnti, uint32_t lc_id, uint32_t tx_queue, uint32_t retx_queue)
 {
-  srsran::rwlock_read_guard lock(rwlock);
   int                       ret = -1;
   if (check_ue_active(rnti)) {
     if (rnti != SRSRAN_MRNTI) {
+      srsran::rwlock_write_guard lock(rwlock);
       ret = scheduler.dl_rlc_buffer_state(rnti, lc_id, tx_queue, retx_queue);
     } else {
+      task_sched.defer_callback(0, [this, tx_queue, lc_id]() {
+        srsran::rwlock_write_guard lock(rwlock);
         for (uint32_t i = 0; i < mch.num_mtch_sched; i++) {
           if (lc_id == mch.mtch_sched[i].lcid) {
             mch.mtch_sched[i].lcid_buffer_size = tx_queue;
           }
         }
+      });
       ret = 0;
     }
   }