3 files changed, 12 insertions, 3 deletions
diff --git a/ChangeLog b/ChangeLog
index fac404b94e..41c0086c5c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Fri Oct 14 05:58:05 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* atomic.h (ATOMIC_INC, ATOMIC_DEC): return old values.
+	  [ruby-dev:44596] [Bug #5439]
+
+	* signal.c (ruby_atomic_exchange): no needs to define on the
+	  platforms where atomic.h is available.
+
 Thu Oct 13 19:29:40 2011  Naohisa Goto  <ngotogenome@gmail.com>
 
 	* atomic.h (ATOMIC_*): use atomic_ops(3C) when SunStudio on Solaris.
diff --git a/atomic.h b/atomic.h
index d131677aa6..33f731927d 100644
--- a/atomic.h
+++ b/atomic.h
@@ -54,11 +54,12 @@ typedef unsigned int rb_atomic_t;
 
 #else
 typedef int rb_atomic_t;
+#define NEED_RUBY_ATOMIC_EXCHANGE
 extern rb_atomic_t ruby_atomic_exchange(rb_atomic_t *ptr, rb_atomic_t val);
 
 # define ATOMIC_SET(var, val) (void)((var) = (val))
-# define ATOMIC_INC(var) (++(var))
-# define ATOMIC_DEC(var) (--(var))
+# define ATOMIC_INC(var) ((var)++)
+# define ATOMIC_DEC(var) ((var)--)
 # define ATOMIC_OR(var, val) ((var) |= (val))
 # define ATOMIC_EXCHANGE(var, val) ruby_atomic_exchange(&(var), (val))
 #endif
diff --git a/signal.c b/signal.c
index 02ec9d3ebc..9b4e15eec0 100644
--- a/signal.c
+++ b/signal.c
@@ -18,7 +18,7 @@
 #include <errno.h>
 #include "atomic.h"
 
-#if !defined(_WIN32) && !defined(HAVE_GCC_ATOMIC_BUILTINS)
+#ifdef NEED_RUBY_ATOMIC_EXCHANGE
 rb_atomic_t
 ruby_atomic_exchange(rb_atomic_t *ptr, rb_atomic_t val)
 {