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-rw-r--r--include/linux/kconfig.h22
1 files changed, 18 insertions, 4 deletions
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index 067eda0e4b3..be342b94c64 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 */