From 512cc11923efee8d1d6698d6e0c56df41374dc3e Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Mon, 9 Jul 2018 15:19:39 -0700
Subject: [PATCH] client: avoid race during monitor shutdown

poll() vs. cancel()
---
 src/client/clientMonitor.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/client/clientMonitor.cpp b/src/client/clientMonitor.cpp
index 01fdc2b..2dd6c3c 100644
--- a/src/client/clientMonitor.cpp
+++ b/src/client/clientMonitor.cpp
@@ -202,7 +202,7 @@ bool Monitor::poll()
     if(!impl) return false;
     Guard G(impl->mutex);
 
-    if(!impl->done && impl->last.next()) {
+    if(!impl->done && impl->op && impl->last.next()) {
         const epics::pvData::PVStructurePtr& ptr = impl->last->pvStructurePtr;
         changed = *impl->last->changedBitSet;
         overrun = *impl->last->overrunBitSet;