[PATCH] CONFIG_* In Comments Considered Harmful

[Matthew Wilcox <willy@debian.org>]

I reviewed the dependency list for a file this morning to see why it was
being unnecessarily recompiled (a little fetish of mine, mostly harmless).
I was a little discombobulated to find this line:

    $(wildcard include/config/higmem.h) \

Naturally, I assumed a typo somewhere.  It turns out there is indeed
a CONFIG_HIGMEM in include/linux/mm.h, but it's in a comment.  The
fixdep script doesn't parse C itself, so it doesn't know that this should
be ignored.  Rather than fix the typo, I deleted the comment; the ifdef'ed
code is a mere two lines so the comment seems unnecessary.

This serves as a useful warning to people -- don't put CONFIG_FOO in a
comment unnecessarily.  Because even when it's true now, maybe the #if
gets changed and the comment doesn't.

Index: include/linux/mm.h
===================================================================
RCS file: /var/cvs/linux-2.6/include/linux/mm.h,v
retrieving revision 1.5
diff -u -p -r1.5 mm.h
--- a/include/linux/mm.h	28 Sep 2003 04:06:20 -0000	1.5
+++ b/include/linux/mm.h	1 Oct 2003 13:15:53 -0000
@@ -196,7 +196,7 @@ struct page {
 #if defined(WANT_PAGE_VIRTUAL)
 	void *virtual;			/* Kernel virtual address (NULL if
 					   not kmapped, ie. highmem) */
-#endif /* CONFIG_HIGMEM || WANT_PAGE_VIRTUAL */
+#endif
 };
 
 /*

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
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