HAL_PX4: print overtime message on stuck task

this should make it easier to narrow down stuck task bugs

libraries/AP_HAL_PX4/HAL_PX4_Class.cpp

@@ -86,7 +86,7 @@ HAL_PX4::HAL_PX4() :
 bool _px4_thread_should_exit = false;        /**< Daemon exit flag */
 static bool thread_running = false;        /**< Daemon status flag */
 static int daemon_task;                /**< Handle of daemon task / thread */
-static bool ran_overtime;
+bool px4_ran_overtime;
 
 extern const AP_HAL::HAL& hal;
 
@@ -109,7 +109,7 @@ static void set_priority(uint8_t priority)
 static void loop_overtime(void *)
 {
     set_priority(APM_OVERTIME_PRIORITY);
-    ran_overtime = true;
+    px4_ran_overtime = true;
 }
 
 static int main_loop(int argc, char **argv)
@@ -165,14 +165,14 @@ static int main_loop(int argc, char **argv)
 
         loop();
 
-        if (ran_overtime) {
+        if (px4_ran_overtime) {
             /*
               we ran over 1s in loop(), and our priority was lowered
               to let a driver run. Set it back to high priority now.
              */
             set_priority(APM_MAIN_PRIORITY);
             perf_count(perf_overrun);
-            ran_overtime = false;
+            px4_ran_overtime = false;
         }
 
         perf_end(perf_loop);

libraries/AP_HAL_PX4/Scheduler.cpp

@@ -22,6 +22,7 @@
 #include "Storage.h"
 #include "RCOutput.h"
 #include "RCInput.h"
+#include <AP_Scheduler.h>
 
 using namespace PX4;
 
@@ -229,8 +230,11 @@ void PX4Scheduler::_run_timers(bool called_from_timer_thread)
     _in_timer_proc = false;
 }
 
+extern bool px4_ran_overtime;
+
 void *PX4Scheduler::_timer_thread(void)
 {
+    uint32_t last_ran_overtime = 0;
     while (!_hal_initialized) {
         poll(NULL, 0, 1);        
     }
@@ -247,6 +251,12 @@ void *PX4Scheduler::_timer_thread(void)
 
         // process any pending RC input requests
         ((PX4RCInput *)hal.rcin)->_timer_tick();
+
+        if (px4_ran_overtime && millis() - last_ran_overtime > 2000) {
+            last_ran_overtime = millis();
+            printf("Overtime in task %d\n", (int)AP_Scheduler::current_task);
+            hal.console->printf("Overtime in task %d\n", (int)AP_Scheduler::current_task);
+        }
     }
     return NULL;
 }