Comment 2 for bug 1697501

Red hat fix :

ksh.spec:
--
- job locking mechanism did not survive compiler optimization (#1123467)
--

ksh-20120801-locking.patch
--
diff -up ksh-20120801/src/cmd/ksh93/include/jobs.h.locking ksh-20120801/src/cmd/ksh93/include/jobs.h
--- ksh-20120801/src/cmd/ksh93/include/jobs.h.locking 2014-06-27 15:51:07.144923719 +0200
+++ ksh-20120801/src/cmd/ksh93/include/jobs.h 2014-06-27 15:52:56.463272276 +0200
@@ -149,15 +149,18 @@ extern struct jobs job;
 #define vmbusy() 0
 #endif

-#define job_lock() (job.in_critical++)
+#define asoincint(p) __sync_fetch_and_add(p,1)
+#define asodecint(p) __sync_fetch_and_sub(p,1)
+
+#define job_lock() asoincint(&job.in_critical)
 #define job_unlock() \
  do { \
   int sig; \
- if (!--job.in_critical && (sig = job.savesig)) \
+ if (asodecint(&job.in_critical)==1 && (sig = job.savesig)) \
   { \
- if (!job.in_critical++ && !vmbusy()) \
+ if (!asoincint(&job.in_critical) && !vmbusy()) \
     job_reap(sig); \
- job.in_critical--; \
+ asodecint(&job.in_critical); \
   } \
  } while(0)
--