fixdep: do not ignore kconfig.h

Villemoes · masahir0y · commit 638e69cf2230 · 2018-03-05T23:48:29.000+09:00
kconfig.h was excluded from consideration by fixdep by 6a5be57 (fixdep: fix extraneous dependencies) to avoid some false positive hits (1) include/config/.h (2) include/config/h.h (3) include/config/foo.h (1) occurred because kconfig.h contains the string CONFIG_ in a comment. However, since dee81e9 (fixdep: faster CONFIG_ search), we have a check that the part after CONFIG_ is non-empty, so this does not happen anymore (and CONFIG_ appears by itself elsewhere, so that check is worthwhile). (2) comes from the include guard, __LINUX_KCONFIG_H. But with the previous patch, we no longer match that either. That leaves (3), which amounts to one [1] false dependency (aka stat() call done by make), which I think we can live with: We've already had one case [2] where the lack of include/linux/kconfig.h in the .o.cmd file caused a missing rebuild, and while I originally thought we should just put kconfig.h in the dependency list without parsing it for the CONFIG_ pattern, we actually do have some real CONFIG_ symbols mentioned in it, and one can imagine some translation unit that just does '#ifdef __BIG_ENDIAN' but doesn't through some other header actually depend on CONFIG_CPU_BIG_ENDIAN - so changing the target endianness could end up rebuilding the world, minus that small TU. Quoting Linus, ... when missing dependencies cause a missed re-compile, the resulting bugs can be _really_ subtle. [1] well, two, we now also have CONFIG_BOOGER/booger.h - we could change that to FOO if we care [2] https://lkml.org/lkml/2018/2/22/838 Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
@@ -283,7 +283,6 @@ static int is_ignored_file(const char *s, int len)
 {
 	return str_ends_with(s, len, "include/generated/autoconf.h") ||
 	       str_ends_with(s, len, "include/generated/autoksyms.h") ||
-	       str_ends_with(s, len, "include/linux/kconfig.h") ||
 	       str_ends_with(s, len, ".ver");
 }
 

Original file line number	Diff line number	Diff line change
`@@ -283,7 +283,6 @@ static int is_ignored_file(const char *s, int len)`
`283`	`283`	`{`
`284`	`284`	`return str_ends_with(s, len, "include/generated/autoconf.h") \|\|`
`285`	`285`	`str_ends_with(s, len, "include/generated/autoksyms.h") \|\|`
`286`		`- str_ends_with(s, len, "include/linux/kconfig.h") \|\|`
`287`	`286`	`str_ends_with(s, len, ".ver");`
`288`	`287`	`}`
`289`	`288`