diff --git a/lib/include/srslte/common/block_queue.h b/lib/include/srslte/common/block_queue.h
index 1d17e9339..3df22b40d 100644
--- a/lib/include/srslte/common/block_queue.h
+++ b/lib/include/srslte/common/block_queue.h
@@ -49,11 +49,23 @@ template<typename myobj>
 class block_queue {
 
 public:
+
+  // Callback functions for mutexed operations inside pop/push methods
+  class call_mutexed_itf {
+  public:
+    virtual void popping(myobj obj) = 0;
+    virtual void pushing(myobj obj) = 0;
+  };
+
   block_queue<myobj>(int capacity = -1) {
     pthread_mutex_init(&mutex, NULL);
     pthread_cond_init(&cv_empty, NULL);
     pthread_cond_init(&cv_full, NULL);
     this->capacity = capacity;
+    mutexed_callback = NULL;
+  }
+  void set_mutexed_itf(call_mutexed_itf *itf) {
+    mutexed_callback = itf;
   }
   void resize(int new_capacity) {
     capacity = new_capacity;
@@ -71,6 +83,9 @@ public:
       }
     }
     q.push(value);
+    if (mutexed_callback) {
+      mutexed_callback->pushing(value);
+    }
     pthread_cond_signal(&cv_empty);
     pthread_mutex_unlock(&mutex);
     return true;
@@ -94,6 +109,9 @@ public:
       *value = q.front(); 
       q.pop();
     }
+    if (mutexed_callback) {
+      mutexed_callback->popping(*value);
+    }
     pthread_cond_signal(&cv_full);
     pthread_mutex_unlock(&mutex);
     return true;
@@ -106,6 +124,9 @@ public:
     }
     myobj value = q.front();
     q.pop();
+    if (mutexed_callback) {
+      mutexed_callback->popping(value);
+    }
     pthread_cond_signal(&cv_full);
     pthread_mutex_unlock(&mutex);
     return value;
@@ -136,6 +157,7 @@ private:
   pthread_mutex_t mutex;
   pthread_cond_t  cv_empty;
   pthread_cond_t  cv_full;
+  call_mutexed_itf *mutexed_callback;
   int capacity;
 };
 
diff --git a/lib/include/srslte/upper/rlc_tx_queue.h b/lib/include/srslte/upper/rlc_tx_queue.h
index dee326ab6..3913670e8 100644
--- a/lib/include/srslte/upper/rlc_tx_queue.h
+++ b/lib/include/srslte/upper/rlc_tx_queue.h
@@ -41,41 +41,38 @@
 
 namespace srslte {
 
-class rlc_tx_queue
+class rlc_tx_queue : public block_queue<byte_buffer_t*>::call_mutexed_itf
 {
 public:
   rlc_tx_queue(uint32_t capacity = 128) : queue((int) capacity) {
     unread_bytes = 0;
+    queue.set_mutexed_itf(this);
+  }
+  // increase/decrease unread_bytes inside push/pop mutexed operations
+  void pushing(byte_buffer_t *msg) {
+    unread_bytes += msg->N_bytes;
+  }
+  void popping(byte_buffer_t *msg) {
+    if (unread_bytes > msg->N_bytes) {
+      unread_bytes -= msg->N_bytes;
+    } else {
+      unread_bytes = 0;
+    }
   }
   void write(byte_buffer_t *msg)
   {
     queue.push(msg);
-    unread_bytes += msg->N_bytes;
   }
 
   void read(byte_buffer_t **msg)
   {
     byte_buffer_t *m = queue.wait_pop();
     *msg = m;
-    if (unread_bytes > (*msg)->N_bytes) {
-      unread_bytes -= (*msg)->N_bytes;
-    } else {
-      unread_bytes = 0;
-    }
   }
 
   bool try_read(byte_buffer_t **msg)
   {
-    if (queue.try_pop(msg)) {
-      if (unread_bytes > (*msg)->N_bytes) {
-        unread_bytes -= (*msg)->N_bytes;
-      } else {
-        unread_bytes = 0;
-      }
-      return true;
-    } else {
-      return false;
-    }
+    return queue.try_pop(msg);
   }
 
   uint32_t size()