From f134abb84e9f6a475cae9cbed302d2e0fdf255bb Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Mon, 8 Jul 2019 10:34:53 -0700
Subject: [PATCH] epicsThread avoid possible data race on joined

---
 modules/libcom/src/osi/epicsThread.cpp | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/modules/libcom/src/osi/epicsThread.cpp b/modules/libcom/src/osi/epicsThread.cpp
index 92f833847..cf4fd4df7 100644
--- a/modules/libcom/src/osi/epicsThread.cpp
+++ b/modules/libcom/src/osi/epicsThread.cpp
@@ -153,11 +153,13 @@ bool epicsThread::exitWait ( const double delay ) throw ()
             if ( this->pThreadDestroyed ) {
                 *this->pThreadDestroyed = true;
             }
-            if(!joined) {
-                {
-                    epicsGuard < epicsMutex > guard ( this->mutex );
-                    joined = true;
-                }
+            bool j;
+            {
+                epicsGuard < epicsMutex > guard ( this->mutex );
+                j = joined;
+                joined = true;
+            }
+            if(!j) {
                 epicsThreadMustJoin(this->id);
             }
             return true;