From 5e8754fd80b0a594f720f44d32bf28c7b06ba5a6 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 14 Jun 2016 14:58:57 +0900 Subject: [PATCH] kconfig.h: allow to use IS_{ENABLE,REACHABLE} in macro expansion The typical usage of IS_ENABLED() is if (IS_ENABLED(CONFIG_FOO)) { ... } or #if IS_ENABLED(CONFIG_FOO) ... #endif The current implementation of IS_ENABLED() includes "||" operator, which works well in those expressions like above. However, there is a case where we want to evaluate a config option beyond those use cases. For example, the OF_TABLE() in include/asm-generic/vmlinux.lds.h needs to evaluate a config option in macro expansion: #define ___OF_TABLE(cfg, name) _OF_TABLE_##cfg(name) #define __OF_TABLE(cfg, name) ___OF_TABLE(cfg, name) #define OF_TABLE(cfg, name) __OF_TABLE(config_enabled(cfg), name) #define _OF_TABLE_0(name) #define _OF_TABLE_1(name) \ ... Here, we can not use IS_ENABLED() because of the "||" operator in its define. It is true config_enabled() works well, but it is a bit ambiguous to be used against config options. This commit makes IS_ENABLED() available in more generic context by calculating "or" with macro expansion only. Do likewise for IS_REACHABLE(). Signed-off-by: Masahiro Yamada Signed-off-by: Michal Marek --- include/linux/kconfig.h | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h index 722c7d2c48d6..15ec117ec537 100644 --- a/include/linux/kconfig.h +++ b/include/linux/kconfig.h @@ -3,6 +3,21 @@ #include +#define __ARG_PLACEHOLDER_1 0, +#define __take_second_arg(__ignored, val, ...) val + +/* + * The use of "&&" / "||" is limited in certain expressions. + * The followings enable to calculate "and" / "or" with macro expansion only. + */ +#define __and(x, y) ___and(x, y) +#define ___and(x, y) ____and(__ARG_PLACEHOLDER_##x, y) +#define ____and(arg1_or_junk, y) __take_second_arg(arg1_or_junk y, 0) + +#define __or(x, y) ___or(x, y) +#define ___or(x, y) ____or(__ARG_PLACEHOLDER_##x, y) +#define ____or(arg1_or_junk, y) __take_second_arg(arg1_or_junk 1, y) + /* * Helper macros to use CONFIG_ options in C/CPP expressions. Note that * these only work with boolean and tristate options. @@ -16,12 +31,10 @@ * 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) ___is_defined(cfg) #define __is_defined(x) ___is_defined(x) #define ___is_defined(val) ____is_defined(__ARG_PLACEHOLDER_##val) #define ____is_defined(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0) -#define __take_second_arg(__ignored, val, ...) val /* * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0 @@ -42,14 +55,13 @@ * This is similar to IS_ENABLED(), but returns false when invoked from * built-in code when CONFIG_FOO is set to 'm'. */ -#define IS_REACHABLE(option) (IS_BUILTIN(option) || \ - (IS_MODULE(option) && __is_defined(MODULE))) +#define IS_REACHABLE(option) __or(IS_BUILTIN(option), \ + __and(IS_MODULE(option), __is_defined(MODULE))) /* * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm', * 0 otherwise. */ -#define IS_ENABLED(option) \ - (IS_BUILTIN(option) || IS_MODULE(option)) +#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option)) #endif /* __LINUX_KCONFIG_H */ -- 2.20.1