From 3393a5c99ef091d05516dcc9add0782dbbc7a16a Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Thu, 17 Oct 2013 17:21:36 +1100
Subject: [PATCH] AP_Baro: prevent a race condition in the SITL baro driver

---
 libraries/AP_Baro/AP_Baro_HIL.cpp | 2 ++
 libraries/AP_Baro/AP_Baro_HIL.h   | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/libraries/AP_Baro/AP_Baro_HIL.cpp b/libraries/AP_Baro/AP_Baro_HIL.cpp
index 5f12548152..9692d0bc4b 100644
--- a/libraries/AP_Baro/AP_Baro_HIL.cpp
+++ b/libraries/AP_Baro/AP_Baro_HIL.cpp
@@ -19,6 +19,7 @@ uint8_t AP_Baro_HIL::read()
     uint8_t result = 0;
 
     if (_count != 0) {
+        hal.scheduler->suspend_timer_procs();
         result = 1;
         Press = ((float)_pressure_sum) / _count;
         Temp = ((float)_temperature_sum) / _count;
@@ -26,6 +27,7 @@ uint8_t AP_Baro_HIL::read()
         _count = 0;
         _pressure_sum = 0;
         _temperature_sum = 0;
+        hal.scheduler->resume_timer_procs();
     }
 
     return result;
diff --git a/libraries/AP_Baro/AP_Baro_HIL.h b/libraries/AP_Baro/AP_Baro_HIL.h
index 63d9b1cafc..9607f63944 100644
--- a/libraries/AP_Baro/AP_Baro_HIL.h
+++ b/libraries/AP_Baro/AP_Baro_HIL.h
@@ -13,7 +13,7 @@ private:
     float Press;
     int32_t _pressure_sum;
     int32_t _temperature_sum;
-    uint8_t _count;
+    volatile uint8_t _count;
 
 public:
     bool init();