From 7e4972a061af78f3d7743725de5a751dc6b33444 Mon Sep 17 00:00:00 2001
From: Michael du Breuil <wicked.shell.scripts@gmail.com>
Date: Sun, 13 May 2018 01:33:58 -0700
Subject: [PATCH] DataFlash: Fix a false reporting of dead IO thread when
 millis() wraps

---
 libraries/DataFlash/DataFlash_File.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/libraries/DataFlash/DataFlash_File.cpp b/libraries/DataFlash/DataFlash_File.cpp
index 00fd126319..015aac7afd 100644
--- a/libraries/DataFlash/DataFlash_File.cpp
+++ b/libraries/DataFlash/DataFlash_File.cpp
@@ -1098,9 +1098,8 @@ bool DataFlash_File::logging_enabled() const
 
 bool DataFlash_File::io_thread_alive() const
 {
-    uint32_t tnow = AP_HAL::millis();
     // if the io thread hasn't had a heartbeat in a full second then it is dead
-    return _io_timer_heartbeat + 1000 > tnow;
+    return (AP_HAL::millis() - _io_timer_heartbeat) < 1000;
 }
 
 bool DataFlash_File::logging_failed() const