2 files changed, 11 insertions, 4 deletions
diff --git a/gr-uhd/lib/usrp_source_impl.cc b/gr-uhd/lib/usrp_source_impl.cc
index 318bdb627d..e57db13a0b 100644
--- a/gr-uhd/lib/usrp_source_impl.cc
+++ b/gr-uhd/lib/usrp_source_impl.cc
@@ -491,9 +491,12 @@ namespace gr {
     bool
     usrp_source_impl::start(void)
     {
+      boost::recursive_mutex::scoped_lock lock(d_mutex);
 #ifdef GR_UHD_USE_STREAM_API
-      _rx_stream = _dev->get_rx_stream(_stream_args);
-      _samps_per_packet = _rx_stream->get_max_num_samps();
+      if(not _rx_stream){
+        _rx_stream = _dev->get_rx_stream(_stream_args);
+        _samps_per_packet = _rx_stream->get_max_num_samps();
+      }
 #endif
       //setup a stream command that starts streaming slightly in the future
       static const double reasonable_delay = 0.1; //order of magnitude over RTT
@@ -537,8 +540,8 @@ namespace gr {
     bool
     usrp_source_impl::stop(void)
     {
+      boost::recursive_mutex::scoped_lock lock(d_mutex);
       this->issue_stream_cmd(::uhd::stream_cmd_t::STREAM_MODE_STOP_CONTINUOUS);
-
       this->flush();
 
       return true;
@@ -603,6 +606,7 @@ namespace gr {
                            gr_vector_const_void_star &input_items,
                            gr_vector_void_star &output_items)
     {
+      boost::recursive_mutex::scoped_lock lock(d_mutex);
 #ifdef GR_UHD_USE_STREAM_API
       //In order to allow for low-latency:
       //We receive all available packets without timeout.
diff --git a/gr-uhd/lib/usrp_source_impl.h b/gr-uhd/lib/usrp_source_impl.h
index 58bb21551c..3cfa1aad35 100644
--- a/gr-uhd/lib/usrp_source_impl.h
+++ b/gr-uhd/lib/usrp_source_impl.h
@@ -22,6 +22,7 @@
 
 #include <gnuradio/uhd/usrp_source.h>
 #include <uhd/convert.hpp>
+#include <boost/thread/mutex.hpp>
 
 static const pmt::pmt_t TIME_KEY = pmt::string_to_symbol("rx_time");
 static const pmt::pmt_t RATE_KEY = pmt::string_to_symbol("rx_rate");
@@ -121,7 +122,7 @@ namespace gr {
       int work(int noutput_items,
                gr_vector_const_void_star &input_items,
                gr_vector_void_star &output_items);
- 
+
     private:
       ::uhd::usrp::multi_usrp::sptr _dev;
       const ::uhd::stream_args_t _stream_args;
@@ -142,6 +143,8 @@ namespace gr {
       //tag shadows
       double _samp_rate;
       double _center_freq;
+
+      boost::recursive_mutex d_mutex;
     };
 
   } /* namespace uhd */