Merge commit 'v3.4-rc3' into rt-3.4-rc3-rt4v3.4-rc3-rt4

1 files changed, 18 insertions, 4 deletions

diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index 067eda0e4b32..be342b94c640 100644
--- a/include/linux/kconfig.h
+++ b/include/linux/kconfig.h
@@ -4,29 +4,43 @@
 #include <generated/autoconf.h>
 
 /*
- * Helper macros to use CONFIG_ options in C expressions. Note that
+ * Helper macros to use CONFIG_ options in C/CPP expressions. Note that
  * these only work with boolean and tristate options.
  */
 
 /*
+ * Getting something that works in C and CPP for an arg that may or may
+ * not be defined is tricky.  Here, if we have "#define CONFIG_BOOGER 1"
+ * we match on the placeholder define, insert the "0," for arg1 and generate
+ * the triplet (0, 1, 0).  Then the last step cherry picks the 2nd arg (a one).
+ * When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and when
+ * the last step cherry picks the 2nd arg, we get a zero.
+ */
+#define __ARG_PLACEHOLDER_1 0,
+#define config_enabled(cfg) _config_enabled(cfg)
+#define _config_enabled(value) __config_enabled(__ARG_PLACEHOLDER_##value)
+#define __config_enabled(arg1_or_junk) ___config_enabled(arg1_or_junk 1, 0)
+#define ___config_enabled(__ignored, val, ...) val
+
+/*
  * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm',
  * 0 otherwise.
  *
  */
 #define IS_ENABLED(option) \
-	(__enabled_ ## option || __enabled_ ## option ## _MODULE)
+	(config_enabled(option) || config_enabled(option##_MODULE))
 
 /*
  * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0
  * otherwise. For boolean options, this is equivalent to
  * IS_ENABLED(CONFIG_FOO).
  */
-#define IS_BUILTIN(option) __enabled_ ## option
+#define IS_BUILTIN(option) config_enabled(option)
 
 /*
  * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0
  * otherwise.
  */
-#define IS_MODULE(option) __enabled_ ## option ## _MODULE
+#define IS_MODULE(option) config_enabled(option##_MODULE)
 
 #endif /* __LINUX_KCONFIG_H */