From 1c95101ae1b1e4a65dfd7d1e6327a955e1f34cda Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@aps.anl.gov>
Date: Fri, 21 Aug 2009 17:32:13 +0000
Subject: [PATCH] Fixed Till's report of non-thread-safe lazy-init.

---
 src/libCom/osi/epicsInterrupt.h          | 15 ++++----
 src/libCom/osi/os/default/osdInterrupt.c | 46 +++++++++++++-----------
 2 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/src/libCom/osi/epicsInterrupt.h b/src/libCom/osi/epicsInterrupt.h
index b5cea5031..93b443810 100644
--- a/src/libCom/osi/epicsInterrupt.h
+++ b/src/libCom/osi/epicsInterrupt.h
@@ -1,27 +1,24 @@
 /*************************************************************************\
-* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
+* Copyright (c) 2009 UChicago Argonne LLC, as Operator of Argonne
 *     National Laboratory.
 * Copyright (c) 2002 The Regents of the University of California, as
 *     Operator of Los Alamos National Laboratory.
-* EPICS BASE Versions 3.13.7
-* and higher are distributed subject to a Software License Agreement found
+* EPICS BASE is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution. 
 \*************************************************************************/
 #ifndef epicsInterrupth
 #define epicsInterrupth
 
-/*THIS MAY BE A BIG PROBLEM */
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #include "shareLib.h"
 
-epicsShareFunc int epicsShareAPI epicsInterruptLock(void);
-epicsShareFunc void epicsShareAPI epicsInterruptUnlock(int key);
-epicsShareFunc int epicsShareAPI epicsInterruptIsInterruptContext(void);
-epicsShareFunc void epicsShareAPI epicsInterruptContextMessage(const char *message);
+epicsShareFunc int epicsInterruptLock(void);
+epicsShareFunc void epicsInterruptUnlock(int key);
+epicsShareFunc int epicsInterruptIsInterruptContext(void);
+epicsShareFunc void epicsInterruptContextMessage(const char *message);
 
 #ifdef __cplusplus
 }
diff --git a/src/libCom/osi/os/default/osdInterrupt.c b/src/libCom/osi/os/default/osdInterrupt.c
index 59407d962..91c5c5681 100644
--- a/src/libCom/osi/os/default/osdInterrupt.c
+++ b/src/libCom/osi/os/default/osdInterrupt.c
@@ -1,18 +1,15 @@
 /*************************************************************************\
-* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
+* Copyright (c) 2009 UChicago Argonne LLC, as Operator of Argonne
 *     National Laboratory.
 * Copyright (c) 2002 The Regents of the University of California, as
 *     Operator of Los Alamos National Laboratory.
-* EPICS BASE Versions 3.13.7
-* and higher are distributed subject to a Software License Agreement found
+* EPICS BASE is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution. 
 \*************************************************************************/
 /* osi/default/osdInterrupt.c */
 
 /* Author:  Marty Kraimer Date:    15JUL99 */
 
-/* This is a version that does not allow osi calls at interrupt level */
-
 #include <stddef.h>
 #include <string.h>
 #include <stdlib.h>
@@ -21,34 +18,41 @@
 
 #define epicsExportSharedSymbols
 #include "epicsMutex.h"
+#include "epicsThread.h"
 #include "cantProceed.h"
 #include "errlog.h"
 #include "epicsInterrupt.h"
 
-static epicsMutexId globalLock=0;
-static int firstTime = 1;
 
-epicsShareFunc int epicsShareAPI epicsInterruptLock()
+static epicsMutexId globalLock = NULL;
+static epicsThreadOnceId onceId = EPICS_THREAD_ONCE_INIT;
+
+static void initOnce(void *junk)
 {
-    if(firstTime) {
-        globalLock = epicsMutexMustCreate();
-        firstTime = 0;
-    }
-    epicsMutexMustLock(globalLock);
-    return(0);
+    globalLock = epicsMutexMustCreate();
 }
 
-epicsShareFunc void epicsShareAPI epicsInterruptUnlock(int key)
+epicsShareFunc int epicsInterruptLock()
 {
-    if(firstTime) cantProceed(
-        "epicsInterruptUnlock called before epicsInterruptLock\n");
+    epicsThreadOnce(&onceId, initOnce, NULL);
+    epicsMutexMustLock(globalLock);
+    return 0;
+}
+
+epicsShareFunc void epicsInterruptUnlock(int key)
+{
+    if (!globalLock)
+        cantProceed("epicsInterruptUnlock called before epicsInterruptLock\n");
     epicsMutexUnlock(globalLock);
 }
 
-epicsShareFunc int epicsShareAPI epicsInterruptIsInterruptContext() { return(0);}
-
-epicsShareFunc void epicsShareAPI epicsInterruptContextMessage(const char *message)
+epicsShareFunc int epicsInterruptIsInterruptContext()
 {
-    errlogPrintf("%s",message);
+    return 0;
+}
+
+epicsShareFunc void epicsInterruptContextMessage(const char *message)
+{
+    errlogPrintf("%s", message);
 }