wait with init of GUI until cell is found and initialized

with the stack refactor we've introduced a regression in which
the GUI was started too early when no cell was found yet.

this caused the GUI to be initilized with only one Tx port. When connecting
to a cell with ports, the GUI plotter would then write
into unitialized memory.

srsue/hdr/phy/sf_worker.h

@@ -63,15 +63,16 @@ public:
   void set_crnti(uint16_t rnti);
   void enable_pregen_signals(bool enabled);
 
-  /* Methods for plotting */
+  ///< Methods for plotting called from GUI thread
   int      read_ce_abs(float* ce_abs, uint32_t tx_antenna, uint32_t rx_antenna);
   uint32_t get_cell_nof_ports()
   {
-    if (cell_initiated) {
-      return cell.nof_ports;
-    } else {
-      return 1;
+    // wait until cell is initialized
+    std::unique_lock<std::mutex> lock(mutex);
+    while (!cell_initiated) {
+      cell_init_cond.wait(lock);
     }
+    return cell.nof_ports;
   }
   uint32_t get_rx_nof_antennas() { return phy->args->nof_rx_ant; }
   int      read_pdsch_d(cf_t* pdsch_d);
@@ -101,6 +102,7 @@ private:
   srslte_cell_t       cell       = {};
   srslte_tdd_config_t tdd_config = {};
 
+  std::condition_variable cell_init_cond;
   bool cell_initiated = false;
 
   cf_t* prach_ptr   = nullptr;

srsue/src/phy/sf_worker.cc

@@ -90,13 +90,12 @@ void sf_worker::reset()
 
 bool sf_worker::set_cell(uint32_t cc_idx, srslte_cell_t cell_)
 {
-  bool                        ret = false;
   std::lock_guard<std::mutex> lock(mutex);
 
   if (cc_idx < cc_workers.size()) {
     if (!cc_workers[cc_idx]->set_cell(cell_)) {
       Error("Setting cell for cc=%d\n", cc_idx);
-      goto unlock;
+      return false;
     }
   } else {
     Error("Setting cell for cc=%d; Not enough CC workers (%zd);\n", cc_idx, cc_workers.size());
@@ -105,11 +104,10 @@ bool sf_worker::set_cell(uint32_t cc_idx, srslte_cell_t cell_)
   if (cc_idx == 0) {
     cell           = cell_;
     cell_initiated = true;
+    cell_init_cond.notify_one();
   }
-  ret = true;
 
-unlock:
-  return ret;
+  return true;
 }
 
 cf_t* sf_worker::get_buffer(uint32_t carrier_idx, uint32_t antenna_idx)
@@ -468,6 +466,9 @@ void* plot_thread_run(void* arg)
   plot_scatter_addToWindowGrid(&psync, (char*)"srsue", 1, row_count++);
 #endif /* SYNC_PLOT_LEN > 0 */
 
+  uint32_t num_tx = worker->get_cell_nof_ports();
+  uint32_t num_rx = worker->get_rx_nof_antennas();
+
   int n;
   int readed_pdsch_re = 0;
   while (!plot_quit) {
@@ -477,8 +478,8 @@ void* plot_thread_run(void* arg)
       n = worker->read_pdsch_d(&tmp_plot2[readed_pdsch_re]);
       readed_pdsch_re += n;
     } else {
-      for (uint32_t tx = 0; tx < worker->get_cell_nof_ports(); tx++) {
-        for (uint32_t rx = 0; rx < worker->get_rx_nof_antennas(); rx++) {
+      for (uint32_t tx = 0; tx < num_tx; tx++) {
+        for (uint32_t rx = 0; rx < num_rx; rx++) {
           n = worker->read_ce_abs(tmp_plot, tx, rx);
           if (n > 0) {
             plot_real_setNewData(&pce[tx][rx], tmp_plot, n);
@@ -502,7 +503,6 @@ void* plot_thread_run(void* arg)
 
 void init_plots(srsue::sf_worker* worker)
 {
-
   if (sem_init(&plot_sem, 0, 0)) {
     perror("sem_init");
     exit(-1);

srsue/src/phy/sync.cc

@@ -374,8 +374,7 @@ bool sync::cell_is_camping()
 
 void sync::run_thread()
 {
-  sf_worker* worker                                      = NULL;
-  sf_worker* last_worker                                 = NULL;
+  sf_worker* worker                                      = nullptr;
   cf_t*      buffer[SRSLTE_MAX_RADIOS][SRSLTE_MAX_PORTS] = {NULL};
 
   bool is_end_of_burst        = false;