From b5a0657adca57556e1a6378a0ac555d76e8193d3 Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@aps.anl.gov>
Date: Fri, 13 May 2016 13:30:55 -0500
Subject: [PATCH 1/2] Applied Till's fix for lp:1581212

---
 documentation/RELEASE_NOTES.html | 14 ++++++++++++++
 src/db/db_access.c               |  9 ++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/documentation/RELEASE_NOTES.html b/documentation/RELEASE_NOTES.html
index d6e89cc60..efec011ba 100644
--- a/documentation/RELEASE_NOTES.html
+++ b/documentation/RELEASE_NOTES.html
@@ -13,6 +13,20 @@
 
 <!-- Insert new items immediately below here ... -->
 
+<h3>Making IOC ca_get operations atomic</h3>
+
+<p>When a CA client gets data from an IOC record using a compound data type such
+as <tt>DBR_TIME_DOUBLE</tt> the value field is fetched from the database in a
+separate call than the other metadata, without keeping the record locked. This
+allows some other thread such as a periodic scan thread a chance to interrupt
+the get operation and process the record in between. CA monitors have always
+been atomic as long as the value data isn't a string or an array, but this race
+condition in the CA get path has now been fixed so the record will stay locked
+between the two fetch operations.</p>
+
+<p>This fixes <a href="https://bugs.launchpad.net/epics-base/+bug/1581212">
+Launchpad bug #1581212</a>, thanks to Till Strauman and Dehong Zhang.</p>
+
 <h3>New CONFIG_SITE variable for running self-tests</h3>
 
 <p>The 'make runtests' and 'make tapfiles' build targets normally only run the
diff --git a/src/db/db_access.c b/src/db/db_access.c
index d9d0bc83f..07cce3fec 100644
--- a/src/db/db_access.c
+++ b/src/db/db_access.c
@@ -32,6 +32,7 @@
 #include "dbCommon.h"
 #include "errMdef.h"
 #include "recSup.h"
+#include "dbLock.h"
 #include "alarm.h"
 #define db_accessHFORdb_accessC
 #include "db_access.h"
@@ -182,6 +183,8 @@ int epicsShareAPI db_get_field_and_count(
     * in the dbAccess.c dbGet() and getOptions() routines.
     */
 
+    dbScanLock(paddr->precord);
+
     switch(buffer_type) {
     case(oldDBR_STRING):
         status = dbGetField(paddr, DBR_STRING, pbuffer, &zero, nRequest, pfl);
@@ -820,8 +823,12 @@ int epicsShareAPI db_get_field_and_count(
         }
         break;
     default:
-        return -1;
+        status = -1;
+        break;
     }
+
+    dbScanUnlock(paddr->precord);
+
     if (status) return -1;
     return 0;
 }

From 6d35ee9c3c5921ba0094f207b334ea8188b73dc0 Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@aps.anl.gov>
Date: Fri, 13 May 2016 13:40:37 -0500
Subject: [PATCH 2/2] Move dbLock.h *after* epicsExportSharedSymbols

---
 src/db/db_access.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/db/db_access.c b/src/db/db_access.c
index 07cce3fec..f60696453 100644
--- a/src/db/db_access.c
+++ b/src/db/db_access.c
@@ -32,15 +32,16 @@
 #include "dbCommon.h"
 #include "errMdef.h"
 #include "recSup.h"
-#include "dbLock.h"
 #include "alarm.h"
 #define db_accessHFORdb_accessC
 #include "db_access.h"
 #undef db_accessHFORdb_accessC
+
 #define epicsExportSharedSymbols
 #include "dbNotify.h"
 #include "dbAccessDefs.h"
 #include "dbEvent.h"
+#include "dbLock.h"
 #include "db_access_routines.h"
 
 #ifndef NULL