vmstat: create fold_diff

Both functions that update global counters use the same mechanism.

Create a function that contains the common code.

Signed-off-by: Christoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Tejun Heo <tj@kernel.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmstat.c

@@ -414,6 +414,15 @@ void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 EXPORT_SYMBOL(dec_zone_page_state);
 #endif
 
+static inline void fold_diff(int *diff)
+{
+	int i;
+
+	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
+		if (diff[i])
+			atomic_long_add(diff[i], &vm_stat[i]);
+}
+
 /*
  * Update the zone counters for the current cpu.
  *
@@ -483,10 +492,7 @@ static void refresh_cpu_vm_stats(int cpu)
 			drain_zone_pages(zone, &p->pcp);
 #endif
 	}
-
-	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
-		if (global_diff[i])
-			atomic_long_add(global_diff[i], &vm_stat[i]);
+	fold_diff(global_diff);
 }
 
 /*
@@ -516,9 +522,7 @@ void cpu_vm_stats_fold(int cpu)
 			}
 	}
 
-	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
-		if (global_diff[i])
-			atomic_long_add(global_diff[i], &vm_stat[i]);
+	fold_diff(global_diff);
 }
 
 /*