Re: [PATCH 12/12] vmstat: include compaction.h when CONFIG_COMPACTION

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

Some of these patches do make the code significantly more complex to
read and follow.  Boy, I hope it's all useful!

On Thu, 30 Sep 2010 12:50:21 +0900
Namhyung Kim <namhyung@gmail.com> wrote:

> This removes following warning from sparse:
> 
>  mm/vmstat.c:466:5: warning: symbol 'fragmentation_index' was not declared. Should it be static?
> 
> Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> ---
>  mm/vmstat.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 355a9e6..30054ea 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -394,6 +394,8 @@ void zone_statistics(struct zone *preferred_zone, struct zone *z)
>  #endif
>  
>  #ifdef CONFIG_COMPACTION
> +#include <linux/compaction.h>
> +
>  struct contig_page_info {
>  	unsigned long free_pages;
>  	unsigned long free_blocks_total;

This isn't a good idea: there's a good chance that someone will later
add a #include <linux/compaction.h> at the top of the file to support
future changes.  So we end up including it twice.

So I assume the below will work OK??

--- a/mm/vmstat.c~vmstat-include-compactionh-when-config_compaction-fix
+++ a/mm/vmstat.c
@@ -18,6 +18,7 @@
 #include <linux/sched.h>
 #include <linux/math64.h>
 #include <linux/writeback.h>
+#include <linux/compaction.h>
 
 #ifdef CONFIG_VM_EVENT_COUNTERS
 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
@@ -395,7 +396,6 @@ void zone_statistics(struct zone *prefer
 #endif
 
 #ifdef CONFIG_COMPACTION
-#include <linux/compaction.h>
 
 struct contig_page_info {
 	unsigned long free_pages;
_