[PATCH] kbuild: fix dependency generation

Commit 2e3646e changed the way the
split config tree is built, but failed to also adjust fixdep accordingly
- if changing a config option from or to m, files referencing the
respective CONFIG_..._MODULE (but not the corresponding CONFIG_...)
didn't get rebuilt.

The problem is that trisate symbol are represent with three different
symbols:
    SYMBOL=n => no symbol defined
    SYMBOL=y => CONFIG_SYMBOL defined to '1'
    SYMBOL=m => CONFIG_SYMBOL_MODULE defined to '1'

But conf_split_config do not distingush between the =y and =m case, so
only the =y case is honoured.

This is fixed in fixdep so when a CONFIG symbol with _MODULE is found we
skip that part and only look for the CONFIG_SYMBOL version.

Signed-off-by: Jan Beulich <[email protected]>
Signed-off-by: Sam Ravnborg <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

scripts/basic/fixdep.c

@@ -28,9 +28,11 @@
  * the dependency on linux/autoconf.h by a dependency on every config
  * option which is mentioned in any of the listed prequisites.
  *
- * To be exact, split-include populates a tree in include/config/,
- * e.g. include/config/his/driver.h, which contains the #define/#undef
- * for the CONFIG_HIS_DRIVER option.
+ * kconfig populates a tree in include/config/ with an empty file
+ * for each config symbol and when the configuration is updated
+ * the files representing changed config options are touched
+ * which then let make pick up the changes and the files that use
+ * the config symbols are rebuilt.
  *
  * So if the user changes his CONFIG_HIS_DRIVER option, only the objects
  * which depend on "include/linux/config/his/driver.h" will be rebuilt,
@@ -245,6 +247,8 @@ void parse_config_file(char *map, size_t len)
 		continue;
 
 	found:
+		if (!memcmp(q - 7, "_MODULE", 7))
+			q -= 7;
 		use_config(p+7, q-p-7);
 	}
 }