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| author | Arnd Bergmann <arnd@arndb.de> | 2015-02-18 14:12:42 -0300 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2015-06-28 13:39:23 -0400 |
| commit | ea0a522aef212afc09cd84503cfea58942b9404a (patch) | |
| tree | 8e8fcb1756daddb12ba7bca9ce178d1e949d34b3 /include | |
| parent | be29be6583683e6e125920cd837141775dde3726 (diff) | |
[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 <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/kconfig.h | 9 |
1 files changed, 9 insertions, 0 deletions
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 */ |