From ea0a522aef212afc09cd84503cfea58942b9404a Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 18 Feb 2015 14:12:42 -0300 Subject: [media] Add and use IS_REACHABLE macro [ Upstream commit 9b174527e7b756cda9f5d9e541f87b7fec9cfdf0 ] In the media drivers, the v4l2 core knows about all submodules and calls into them from a common function. However this cannot work if the modules that get called are loadable and the core is built-in. In that case we get drivers/built-in.o: In function `set_type': drivers/media/v4l2-core/tuner-core.c:301: undefined reference to `tea5767_attach' drivers/media/v4l2-core/tuner-core.c:307: undefined reference to `tea5761_attach' drivers/media/v4l2-core/tuner-core.c:349: undefined reference to `tda9887_attach' drivers/media/v4l2-core/tuner-core.c:405: undefined reference to `xc4000_attach' This was working previously, until the IS_ENABLED() macro was used to replace the construct like #if defined(CONFIG_DVB_CX24110) || (defined(CONFIG_DVB_CX24110_MODULE) && defined(MODULE)) with the difference that the new code no longer checks whether it is being built as a loadable module itself. To fix this, this new patch adds an 'IS_REACHABLE' macro, which evaluates true in exactly the condition that was used previously. The downside of this is that this trades an obvious link error for a more subtle runtime failure, but it is clear that the change that introduced the link error was unintentional and it seems better to revert it for now. Also, a similar change was originally created by Trent Piepho and then reverted by teh change to the IS_ENABLED macro. Ideally Kconfig would be used to avoid the case of a broken dependency, or the code restructured in a way to turn around the dependency, but either way would require much larger changes here. Fixes: 7b34be71db53 ("[media] use IS_ENABLED() macro") See-also: c5dec9fb248e ("V4L/DVB (4751): Fix DBV_FE_CUSTOMISE for card drivers compiled into kernel") Signed-off-by: Arnd Bergmann Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- include/linux/kconfig.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include') diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h index be342b94c640..16cfb3448568 100644 --- a/include/linux/kconfig.h +++ b/include/linux/kconfig.h @@ -43,4 +43,13 @@ */ #define IS_MODULE(option) config_enabled(option##_MODULE) +/* + * IS_REACHABLE(CONFIG_FOO) evaluates to 1 if the currently compiled + * code can call a function defined in code compiled based on CONFIG_FOO. + * 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) (config_enabled(option) || \ + (config_enabled(option##_MODULE) && config_enabled(MODULE))) + #endif /* __LINUX_KCONFIG_H */ -- cgit v1.2.3