Re: [2.6 patch] fix mm/mm_init.c compilation

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 4 Aug 2008 21:19:15 +0300
Adrian Bunk <bunk@kernel.org> wrote:

> This patch fixes the following compile error with gcc 3.2:
> 
> <--  snip  -->
> 
> ...
>   CC      mm/mm_init.o
> /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/mm_init.c:77:1: directives may not be used inside a macro argument
> /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/mm_init.c:76:47: unterminated argument list invoking macro "mminit_dprintk"
> /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/mm_init.c: In function `mminit_verify_pageflags_layout':
> /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/mm_init.c:80: `mminit_dprintk' undeclared (first use in this function)
> /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/mm_init.c:80: (Each undeclared identifier is reported only once
> /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/mm_init.c:80: for each function it appears in.)
> /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/mm_init.c:80: syntax error before numeric constant
> make[2]: *** [mm/mm_init.o] Error 1
> 
> <--  snip  -->
> 
> 
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -63,6 +63,13 @@ void __init mminit_verify_pageflags_layout(void)
>  {
>  	int shift, width;
>  	unsigned long or_mask, add_mask;
> +	int sections_shift;
> +
> +#ifdef SECTIONS_SHIFT
> +	sections_shift = SECTIONS_SHIFT;
> +#else
> +	sections_shift = 0;
> +#endif
>  
>  	shift = 8 * sizeof(unsigned long);
>  	width = shift - SECTIONS_WIDTH - NODES_WIDTH - ZONES_WIDTH;
> @@ -74,11 +81,7 @@ void __init mminit_verify_pageflags_layout(void)
>  		NR_PAGEFLAGS);
>  	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts",
>  		"Section %d Node %d Zone %d\n",
> -#ifdef SECTIONS_SHIFT
> -		SECTIONS_SHIFT,
> -#else
> -		0,
> -#endif
> +		sections_shift,
>  		NODES_SHIFT,
>  		ZONES_SHIFT);
>  	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_offsets",

OK, ifdefs inside macro expansion aren't a great idea.

Mel, is there any erason why we shouldn't do it this way?

 include/linux/mmzone.h |    3 ++-
 mm/mm_init.c           |    4 ----

 2 files changed, 2 insertions(+), 5 deletions(-)

diff -puN include/linux/mmzone.h~a include/linux/mmzone.h
--- a/include/linux/mmzone.h~a
+++ a/include/linux/mmzone.h
@@ -831,7 +831,7 @@ static inline unsigned long early_pfn_to
 #ifdef CONFIG_SPARSEMEM
 
 /*
- * SECTION_SHIFT    		#bits space required to store a section #
+ * SECTIONS_SHIFT    		#bits space required to store a section #
  *
  * PA_SECTION_SHIFT		physical address to/from section number
  * PFN_SECTION_SHIFT		pfn to/from section number
@@ -973,6 +973,7 @@ static inline int pfn_present(unsigned l
 #define early_pfn_valid(pfn)	pfn_valid(pfn)
 void sparse_init(void);
 #else
+#define SECTIONS_SHIFT		0
 #define sparse_init()	do {} while (0)
 #define sparse_index_init(_sec, _nid)  do {} while (0)
 #endif /* CONFIG_SPARSEMEM */
diff -puN mm/mm_init.c~a mm/mm_init.c
--- a/mm/mm_init.c~a
+++ a/mm/mm_init.c
@@ -74,11 +74,7 @@ void __init mminit_verify_pageflags_layo
 		NR_PAGEFLAGS);
 	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_shifts",
 		"Section %d Node %d Zone %d\n",
-#ifdef SECTIONS_SHIFT
 		SECTIONS_SHIFT,
-#else
-		0,
-#endif
 		NODES_SHIFT,
 		ZONES_SHIFT);
 	mminit_dprintk(MMINIT_TRACE, "pageflags_layout_offsets",
_