mm: introduce for_each_populated_zone() macro

Impact: cleanup

In almost cases, for_each_zone() is used with populated_zone().  It's
because almost function doesn't need memoryless node information.
Therefore, for_each_populated_zone() can help to make code simplify.

This patch has no functional change.

[akpm@linux-foundation.org: small cleanup]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 6 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index f5fc2d7680f2..33e2e4a819f9 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -321,13 +321,10 @@ static int create_mem_extents(struct list_head *list, gfp_t gfp_mask)
 
         INIT_LIST_HEAD(list);
 
-        for_each_zone(zone) {
+        for_each_populated_zone(zone) {
                 unsigned long zone_start, zone_end;
                 struct mem_extent *ext, *cur, *aux;
 
-                if (!populated_zone(zone))
-                        continue;
-
                 zone_start = zone->zone_start_pfn;
                 zone_end = zone->zone_start_pfn + zone->spanned_pages;
 
@@ -804,8 +801,8 @@ static unsigned int count_free_highmem_pages(void)
         struct zone *zone;
         unsigned int cnt = 0;
 
-        for_each_zone(zone)
-                if (populated_zone(zone) && is_highmem(zone))
+        for_each_populated_zone(zone)
+                if (is_highmem(zone))
                         cnt += zone_page_state(zone, NR_FREE_PAGES);
 
         return cnt;